Selective Metalations of 1,4-Dithiins and Condensed Analogs using TMP-Magnesium and -Zinc Bases

Transcription

1 Selective Metalations of,4-dithiins and Condensed Analogs using TMP-Magnesium and -Zinc Bases Alicia Castelló-Micó, a Julia Nafe, a Kosuke Higashida, a Konstantin Karaghiosoff, a Marc Gingras, b Paul Knochel a * a Department Chemie, Ludwig-Maximilians-Universita t, Butenandtstrasse 5-3, 8377 München, Germany b CNRS, Aix-Marseille Université, CINAM UMR 7325, 63 Avenue de Luminy, 3288 Marseille, France *Paul.Knochel@cup.uni-muenchen.de Supporting Information S

2 Table of contents A) General Information S3 B) Starting Material Synthesis S3-S6 C) General Procedures S6-S7 D) Compounds Synthesized According to the General Procedures S7-S3 E) NMR Spectra S32-S70 F) Single Crystal X-Ray Diffraction Studies S7-S8 S2

3 A) General Information All air and moisture sensitive reactions were carried out under argon atmosphere in flame-dried glassware. Syringes which were used to transfer anhydrous solvents or reagents were purged with argon prior to use. THF was continuously refluxed and freshly distilled from sodium benzophenone ketyl under nitrogen and stored over molecular sieves. Reactions were monitored by gas chromatography (GC and GC-MS) or thin layer chromatography (TLC). TLC was performed with aluminium plates covered with SiO 2 (Merck 60, F-254) and visualized by UV detection. Yields refer to isolated yields of compounds estimated to be > 95% pure as determined by H-NMR (25 C) and capillary GC. NMR spectra were recorded in solutions in CDCl 3 with residual solvent reference (δ = 7.26 ppm for H-NMR and δ = 77. ppm for 3 C-NMR). Abbreviations for signal coupling are as follows: s, singlet; d, doublet; t, triplet; q, quartet; m, multiplet; br, broad. Purification by column chromatography was performed using SiO 2 ( mm, mesh ASTM) from Merck or using preparative high performance liquid chromatography (HPLC). All reagents were obtained from commercial sources. TMPH was distilled prior to use. CuCN, ZnCl 2 and LiCl were obtained from Merck. B) Starting material synthesis. Preparation of Organometallic reagents: i-prmgcl LiCl was purchased as a solution in THF from Rockrood Lithium and titrated against iodine prior to use. Preparation of CuCN 2LiCl solution: CuCN 2LiCl solution ( M in THF) was prepared by drying CuCN (7.7 g, 80 mmol) and LiCl (6.77 g, 60 mmol) in a Schlenk-flask under vacuum at 40 C for 5 h. After cooling, dry THF (80 ml) was added and stirring was continued until all salts were dissolved (24 h). Preparation of ZnCl 2 solution: ZnCl 2 solution ( M in THF) was prepared by drying ZnCl 2 (36.3 g, 00 mmol) in a Schlenk-flask under vacuum at 40 C for 5 h. After cooling, dry THF (00 ml) was added and stirring was continued until all salts were dissolved (2 h). Preparation of TMPMgCl LiCl (6): 2 In a dry and argon flushed Schlenk-flask TMPH (2,2,6,6-tetramethylpiperidine, 4.8 g, 05 mmol) was added to iprmgcl LiCl (7.4 ml, 00 mmol,.40 M in THF) at 25 C and the mixture was stirred for 3 days at 25 C. The freshly prepared TMPMgCl LiCl was titrated prior to use at 0 C with benzoic acid using 4-(phenylazo)diphenylamine as indicator. Preparation of TMPZn LiCl (3): Krasovskiy, A.; Knochel, P. Synthesis 2006, 2006, Krasovskiy, A.; Krasovskaya, V.; Knochel, P. Angew. Chem. 2006, 8, 3024; Angew. Chem., Int. Ed. 2006, 45, S3

4 A flame-dried and argon flushed Schlenk-flask, equipped with a magnetic stirring bar and rubber septum, was charged with TMPH (2,2,6,6-tetramethylpiperidine, ml, 60 mmol) dissolved in THF (60 ml). The solution was cooled to -40 C and nbuli (25 ml, 60 mmol, 2.4 M in hexane) was added dropwise and the mixture was allowed to warm up to -0 C for h. ZnCl 2 solution (66 ml, 66 mmol, M in THF) was added dropwise and the resulting solution was stirred for 30 min at -0 C and then 30 min at 25 C. The solvents were removed under vacuum affording a yellowish solid. Freshly distilled THF was then slowly added and the solution was stirred until all salts were completely dissolved. The freshly prepared TMPZnCl LiCl was titrated prior to use at 0 C with benzoic acid using 4-(phenylazo)-diphenylamine as indicator. 2. Preparation of,4-dithiine () 3 According to the literature, 3 thionyl chloride (8.5 g,.3 ml, 56 mmol) was added to a solution of,4-dithiane-2,5-diol (6.77 g, 44.4 mmol) in dry DMF (250 ml) at 0 C. After the addition, the reaction mixture was stirred at 25 C for 2 h. The product which codistills with DMF, was distilled under reduced pressure (00 C, 270 mbar). After reducing half of the volume, another dry DMF (00 ml) was added to the reaction flask and the distillation was continued until a black residue was left. The distilled DMF was extracted with water (50 ml) and Et 2O (400 ml). The organic phase was washed with water (3 x 50 ml), sat. aq. NaHCO 3 solution (2 x 00 ml) and sat. aq. NaCl solution (00 ml). The organic phase was dried over anhydrous MgSO 4 and, after filtration, the solvent was evaporated in vacuo.,4-dithiine () was obtained as yellow liquid (4.8 g, 8%) and was used without further purification. H NMR (400 MHz, CDCl 3) δ/ppm: 6.8 (s, 4H). 3. Preparation of bis(phenylsulfonyl)sulfide (20) 4 According to the literature, 4 sodium benzenesulfinate (4 g, 250 mmol) was suspended in dry Et 2O (300 ml) and a solution of sulfur dichloride (3 g, 25 mmol) in dry Et 2O (50 ml) was added dropwise. The mixture was stirred for 2 h at 40 C. Afterwards water was added and the insoluble product was filtered off. After recrystallization from acetone, bis(phenylsulfonyl)sulfide was obtained as white crystals (24 g, 60%). H NMR (400 MHz, CDCl 3) δ/ppm: 8.02 (d, J=7.6 Hz, 4 H), 7.7 (t, J=7.3 Hz, 2 H), 7.59 (t, J=7.8 Hz, 4 H). 3 Grant, A. S.; Faraji-Dana, S.; Graham, E. J. Sulfur Chem. 2009, 30, (a) Allared, F.; Hellberg, J.; Remonen, T. Tetrahedron Lett. 2002, 43, 553. (b) Dostert, C.; Wanstrath, C.; Frank, W.; Müller, T. J. J. Chem. Commun. 202, 48, 727. S4

5 4. Preparation of,4,5,8-tetrathianaphthalene (4) 4.. Synthesis of tetraethylammonium bis(,3-dithiole-2-thione-4,5-dithiol) zincate (2) According to the literature, 5 an oven-dried L round-bottomed flask, equipped with a mechanical stirrer, a 250-mL pressure-equalizing dropping funnel, and a gas inlet tube, was connected to nitrogen. The flask was charged with sodium (4.6 g, 200 mmol) and placed in an ice-water bath. Carbon disulfide (36 ml, 600 mmol) was introduced into the flask through the dropping funnel, after which 60 ml of DMF were added dropwise over 45 min. After the addition, the reaction mixture was allowed to warm to 25 C and stir overnight. Methanol (20 ml) was added slowly through the dropping funnel to the reaction mixture in an ice bath. Afterwards, a mixture of methanol (80 ml) and deionized water (00 ml), was then added rapidly through the dropping funnel. A solution of ZnCl 2 (4. g, 30 mmol) in concentrated aqueous ammonium hydroxide (50 ml) and methanol (00 ml) was then added through the dropping funnel. A solution of tetraethylammonium bromide ( g, 50 mmol) in water (50 ml) was added dropwise via the dropping funnel with vigorous stirring over at least 45 min, and the solution was stirred 2 h. The precipitated was collected by suction on a Büchner funnel and washed with water (00 ml), isopropanol (80 ml) and diethyl ether (40 ml). The product was then dried in a desiccator under vacuum affording 2 as a red powder (5 g, 84%). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 209.4, 35., 52.0, Synthesis of 4,5-dibenzoylthio-,3-dithiole--thione (22). According to the literature, 5 tetraethylammonium bis(,3-dithiole-2-thione-4,5-dithio) zincate (2, 6 g, 223 mmol) was dissolved in acetone (400 ml) of benzoyl chloride (48.4 g, 345 mmol) was added dropwise. The reaction mixture was stirred for 2 h and the resulting yellow-light brown precipitate was collected by suction and washed with water (500 ml) and acetone (300 ml). This crude material was dissolved in chloroform (350 ml), Norit ( g) was added and the mixture was heated under reflux for 0 min. The mixture was filtered while still hot, and washed with chloroform. The combined chloroform solutions were concentrated to 50 ml and the resulting mixture was warmed and methanol (50 ml) was added portionwise with stirring. The solution was then left overnight in the refrigerator. The resulting crystalline precipitate was collected by suction and air-dried, affording 22 (8.5 g, 43%). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 22.5, 85.6, 35.0, 34.9, 33.8, 29.3, Hansen, T. K.; Becher, J.; Joergensen, T.; Varma, K. S.; Khedekar, R.; Cava, M. P.Organic Syntheses, 996, 73, 270. S5

6 4.3. Synthesis of,4,5,8-tetrathianaphthalene (4). According to the literature, 6 sodium (3.0 g, 30 mmol) was dissolved in ethanol (50 ml) under N 2 in a 3-necked L round bottom flask equiped with a stir bar and two 250 ml addition funnels. Then, THF (65 ml) was added and the solution was refluxed. At that moment, 4,5-bis(benzoylthio)-,3-dithiole--thione (23, 5.3 g, 3 mmol in 80 ml of THF) and cis-,2-dichloroethylene (2.6 g, 27mmol in 80 ml of THF) were added simultaneously dropwise over h to the sodium ethoxide solution. The reaction mixture was refluxed for 2 h. Water (30 ml) was added to dissolve the precipitate and then, the THF was removed under reduced pressure. The solid was collected and washed with water. The solid was purified by flash column chromatography on silica gel (ihexane) yielding 4 as yellow solid (.6 g, 60%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.46 (s, 4 H). C) General procedures Typical Procedure for the magnesiation of,4-dithiine () with TMPMgCl LiCl (6) (TP): A dry and argon flushed Schlenk-flask was charged with a solution of,4-dithiine (; equiv) in dry THF ( M). TMPMgCl LiCl (6;. equiv) was added dropwise at -40 C and the reaction mixture was stirred for h. The completion of the reaction was checked by GC analysis of reaction aliquots quenched with iodine in dry THF. Typical Procedure 2 for the magnesiation or zincation of monofunctionalized,4- dithiine derivatives (9) withtmpmgcl LiCl (6) or TMPZnCl LiCl (7) (TP2): A dry and argon flushed Schlenk-flask was charged with a solution of the corresponding monofunctionalized,4-dithiine derivative (9; equiv) in dry THF ( M). TMPMgCl LiCl (6; 5 -. equiv) or TMPZnCl LiCl (7;. equiv) was added dropwise at the indicated temperature and the reaction mixture was stirred for h. The completion of the reaction was checked by TLC analysis of reaction aliquots quenched with iodine in dry THF. Typical Procedure 3 for the magnesiation of,4,5,8-tetrathianaphthalene (4) with TMPMgCl LiCl (6) (TP3): A dry and argon flushed Schlenk-flask was charged with a solution of,4,5,8- tetrathianaphthalene (4; equiv) in dry THF (3 M). TMPMgCl LiCl (6;.2 equiv) was added dropwise at -78 C and the reaction mixture was stirred for 0 min. The completion of the reaction was checked by GC analysis of reaction aliquots quenched with iodine in dry THF. 6 Meline, R. L.; Elsenbaumer, R. L. Synthetic Metals, 997, 86, 845. S6

7 Typical Procedure 4 for the zincation of monofunctionalized,4,5,8- tetrathianaphthalene derivatives (4) with TMPZnCl LiCl (7) (TP4): A dry and argon flushed Schlenk-flask was charged with a solution of the corresponding monofunctionalized,4,5,8-tetrathianaphthalene derivative (4; equiv) in dry THF (3 M). TMPZnCl LiCl (7;. equiv) was added dropwise at -40 C and the reaction mixture was stirred for h. The completion of the reaction was checked by TLC analysis of reaction aliquots quenched with iodine in dry THF. Typical Procedure 5 for the zincation of,4,5,6,9,0-hexathiaanthracene (5) with TMPZnCl LiCl (7) (TP5): A dry and argon flushed Schlenk-flask was charged with a solution of,4,5,6,9,0- hexathiaanthracene (5; equiv) in dry THF (0.03 M). TMPZnCl LiCl (7;. equiv) was added dropwise at -40 C and the reaction mixture was stirred for 2 h. The completion of the reaction was checked by GC analysis of reaction aliquots quenched with iodine in dry THF. D) Compounds synthesized according to the general procedures. Preparation of monofunctionalized,4-dithiine derivatives.. Synthesis of 2-iodo-,4-dithiine (9a) According to TP,,4-dithiine (; 6 mg, mmol) was dissolved in dry THF (2 ml). TMPMgCl LiCl (9 ml,. mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. The freshly prepared magnesium reagent was added to a solution of iodine (77 mg, mmol) in dry THF ( ml) at -78 C. The resulting solution was stirred at this temperature for h and was then quenched with sat. aq. Na 2S 2O 3 solution (5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 9a as yellow liquid (27 mg, 75%). H NMR (400 MHz, CDCl 3) δ/ppm: (m, 2H), 6.24 (d, J = 6.6, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 25.9, 22.7, 2.7, IR (Diamond-ATR, neat) ~ /cm - : 3025, 292, 678, 598, 554, 534, 53, 469, 273, 27, 34, 885, 839, 794, 768, 732, 668, 566. MS (70 ev, EI) m/z (%): 242 (69), 5 (00), 89 (2), 7 (78), 57 (30), 45 (56). HRMS (EI): m/z (M + ) for C 4H 3IS 2: calcd ; found Synthesis of 2-bromo-,4-dithiine (9b) S7

8 According to TP,,4-dithiine (; 6 mg, 5.0 mmol) was dissolved in dry THF (0 ml). TMPMgCl LiCl (4.95 ml, 5.5 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. The freshly prepared magnesium reagent was added to a solution of,2-dibromotetrachloroethane (.4 g, 3.5 mmol) in dry THF (5 ml) at -78 C. The resulting solution was stirred at this temperature for 2 h and was then quenched with sat. aq. NH 4Cl solution (0 ml), extracted with Et 2O (3 x 80 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 9b as yellow liquid (529 mg, 78%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.40 (d, J=6.4 Hz, H), (m, 2 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 26.0, 22.8, 2.9, IR (Diamond-ATR, neat) ~ /cm - : 303, 563, 555, 524, 503, 493, 468, 446, 43, 322, 275, 28, 88, 35, 09, 070, 03, 0, 99, 886, 860, 827, 799, 773, 752, 70, 668. MS (70 ev, EI) m/z (%): 96 (53), 94 (47), 5 (00), 7 (4), 57 (0), 45 (6). HRMS (EI): m/z (M + ) for C 4H 3BrS 2: calcd ; found Synthesis of 2-chloro-,4-dithiine (9c) According to TP,,4-dithiine (; 83 mg, 7.0 mmol) was dissolved in dry THF (4 ml). TMPMgCl LiCl (6.94 ml, 7.7 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. The freshly prepared magnesium reagent was added to a solution of benzenesulfonyl chloride (865 mg, 4.9 mmol) in dry THF (5 ml) at -78 C. The resulting solution was stirred at this temperature for 2 h and was then quenched with sat. aq. NH 4Cl solution (0 ml), extracted with Et 2O (3 x 80 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 9c as yellow liquid (43 mg, 56%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.37 (d, J=6.6 Hz, H), 6.33 (d, J=6.6 Hz, H), 6.6 (s, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 23.0, 22.6, 22.3, 7.3. IR (Diamond-ATR, neat) ~ /cm - : 3035, 2922, 279, 60, 579, 548, 528, 455, 402, 278, 206, 36, 065, 97, 928, 896, 88, 770, 668. MS (70 ev, EI) m/z (%): 52 (2), 50 (52), 5 (87), 05 (3), 89 (4), 88 (7), 79 (2), 7 (45), 58 (23), 57 (52), 45 (00). S8

9 HRMS (EI): m/z (M + ) for C 4H 3ClS 2: calcd ; found Synthesis of,4-dithiine-2-carbonitrile (9d) According to TP,,4-dithiine (; 6 mg, mmol) was dissolved in dry THF (2 ml). TMPMgCl LiCl (9 ml,. mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. The freshly prepared magnesium reagent was added to a solution of p-toluenesulfonyl cyanide (27 mg, mmol) in dry THF (2 ml) at -60 C. The resulting solution was stirred at this temperature for 2 h and was then quenched with sat. aq. NH 4Cl solution (5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/et 2O, 95:5) yielding 9d as orange oil (59 mg, 60%). H NMR (400 MHz, CDCl 3) δ/ppm: 7.3 (s, H), 6.32 (d, J=6.6 Hz, H), 6.28 (d, J=6.6 Hz, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 4, 22.0, 2., 4.5, IR (Diamond-ATR, neat) ~ /cm - : 3034, 2924, 227, 654, 594, 558, 525, 447, 33, 28, 240, 76, 40, 084, 054, 999, 958, 932, 892, 85, 805, 785, 674, 66. MS (70 ev, EI) m/z (%): 4 (00), 4 (9), 96 (3), 7 (27), 45 (33). HRMS (EI): m/z (M + ) for C 5H 3NS 2: calcd. 4707; found Synthesis of -(,4-dithiin-2-yl)-N,N-dimethylmethanamine (9e) A dry and argon-flushed Schlenk-flask was charged with N,N,N,N - tetramethylmethanediamine (2 mg,. mmol) and anydrous CH 2Cl 2 (. ml). Trifluoroacetic anhydride (23 mg,. mmol) was added dropwise and the solution was stirred for 5 min at 0 C. 7 In a second dry and argon-flushed Schlenk flask, according to TP,,4-dithiine (; 6 mg, mmol) was dissolved in dry THF (2 ml). TMPMgCl LiCl (4 ml,. mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. Then, the previously prepared methylene(dimethyl)iminium trifluoroacetate was added at -78 C to the magnesiated,4-dithiin solution. The reaction mixture was stirred for 3 h warming to 25 ºC. The crude mixture was quenched with sat. aq. NaHCO 3 and extracted with EtOAc (3 x 20 ml). The combined organic layers were washed with sat. aq. NaCl and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column 7 V. Werner, M. Ellwart, A. J. Wagner, P. Knochel, Org. Lett. 205, 7, S9

10 chromatography on silica gel (ihexane/etoac, 8:2) yielding 9e as orange oil (00 mg, 58%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.26 (d, J=7.0 Hz, H), 6.24 (d, J=7.0 Hz, H), 6.02 (s, H), 3.0 (s, 2 H), 2.24 (s, 6 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 35.5, 22.3, 2.9, 7.3, 64.5, IR (Diamond-ATR, neat) ~ /cm - : 3025, 2973, 2942, 2853, 287, 277, 538, 464, 450, 35, 262, 225, 74, 47, 09, 042, 023, 982, 890, 859, 834, 809, 782, 73, 668. MS (70 ev, EI) m/z (%): 73 (23), 30 (6), 97 (8), 58 (00), 45 (), 44 (6), 43 (8), 42 (), 4 (7). HRMS (EI): m/z (M + ) for C 7H NS 2: calcd ; found Synthesis of (,4-dithiin-2-yl)(phenyl)methanol (9f) According to TP,,4-dithiine (; 58 mg, mmol) was dissolved in dry THF ( ml). TMPMgCl LiCl (0 ml, 5 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. The freshly prepared magnesium reagent was added to a solution of benzaldehyde (37 mg, 5 mmol) in dry THF ( ml) at -78 C. The resulting solution was stirred at this temperature for 2 h and was then quenched with sat. aq. NH 4Cl solution (5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/etoac, 7:) yielding 9f as yellowish solid (75 mg, 97%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: (m, 6 H), 6.34 (d, J=6.8 Hz, H), 6.28 (s, H), 6.20 (d, J=6.8 Hz, H), 5.36 (s, H), 2.6 (br. s., H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 4, 39.6, 28.5, 28.3, 26.6, 23.7, 2.9, 8.3, IR (Diamond-ATR, neat) ~ /cm - : 379, 327, 3029, 306, 2894, 2666, 957, 887, 728, 7, 598, 587, 573, 564, 537, 492, 46, 446, 392, 372, 322, 30, 267, 28, 87, 77, 57, 42, 092, 070, 03, 0, 99, 892, 859, 827, 794, 777, 748, 699, 687, 672. MS (70 ev, EI) m/z (%): 223 (5), 222 (00), 6 (60), 07 (23), 05 (36), 03 (3), 79 (54), 77 (64), 7 (36), 58 (), 45 (23). HRMS (EI): m/z (M + ) for C H 0OS 2: calcd ; found S0

11 .7. Synthesis of ethyl,4-dithiine-2-carboxylate (9g) According to TP,,4-dithiine (; 697 mg, 6.0 mmol) was dissolved in dry THF (2 ml). TMPMgCl LiCl (5.95 ml, 6.6 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. The freshly prepared magnesium reagent was added to a solution of ethyl cyanoformate (47 mg, 4.2 mmol) in dry THF (6 ml) at -60 C. The resulting solution was stirred at this temperature for 2 h and was then quenched with sat. aq. NH 4Cl solution (0 ml), extracted with Et 2O (3 x 70 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/et 2O, 95:5) yielding 9g as red liquid (704 mg, 89%). H NMR (300 MHz, CDCl 3) δ/ppm: 7.29 (s, H), 6.9 (d, J=7. Hz, H), 6.03 (d, J=7. Hz, H), 4.26 (q, J=7. Hz, 2 H),.32 (t, J=7. Hz, 4 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 6., 33.8, 25.6, 22.0, 9.6, 62.0, 4.. IR (Diamond-ATR, neat) ~ /cm - : 3037, 2980, 2932, 2904, 702, 573, 533, 464, 444, 39, 366, 292, 243, 28, 7,, 094, 040, 994, 973, 889, 850, 830, 790, 73, 666. MS (70 ev, EI) m/z (%): 90 (2), 89 (2), 88 (00), 62 (0), 60 (9), 43 (6), 42 (26), 5 (22), 4 (8), (9). HRMS (EI): m/z (M + ) for C 7H 8O 2S 2: calcd ; found Synthesis of (,4-dithiin-2-yl)(phenyl)methanone (9h) According to TP,,4-dithiine (;.6 g, 0.0 mmol) was dissolved in dry THF (20 ml). TMPMgCl LiCl (9.9 ml, mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. ZnCl 2 solution (2.0 ml, 2.0 mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min. CuCN.2LiCl solution (2.0 ml, 2.0 mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min, before benzoyl chloride (984 mg, 7.0 mmol) was added. The reaction mixture was stirred at 25 C for 2 h and was then quenched with sat. aq. NH 4Cl/NH 3 solution (8:, 50 ml), extracted with Et 2O (3 x 00 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/et 2O, 94:6) yielding 9h as red liquid (.20 g, 78%). H NMR (400 MHz, CDCl 3) δ/ppm: 7.69 (d, J=7.6 Hz, 2 H), 7.56 (t, J=7.6 Hz, H), 7.45 (t, J=7.6 Hz, 2 H), 6.96 (s, H), 6.28 (d, J=7.6 Hz, H), 6.0 (d, J=7.6 Hz, H). S

12 3 C NMR (0 MHz, CDCl 3) δ/ppm: 88.6, 37.0, 36.8, 34.2, 32.5, 29., 28.4, 22.6, 9.7. IR (Diamond-ATR, neat) ~ /cm - : 3092, 3035, 2973, 2955, 2928, 2868, 2360, 748, 693, 638, 563, 528, 468, 396, 366, 26, 26, 020, 938, 900, 872, 858, 770, 737, 666. MS (70 ev, EI) m/z (%): 220 (40), 05 (00), 77 (63). HRMS (EI): m/z (M + ) for C H 8OS 2: calcd ; found Synthesis of cyclopropyl(,4-dithiin-2-yl)methanone (9i) According to TP,,4-dithiine (; 232 mg, 2.0 mmol) was dissolved in dry THF (4 ml). TMPMgCl LiCl (.98 ml, 2.2 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. ZnCl 2 solution (2.4 ml, 2.4 mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min. CuCN.2LiCl solution (2.4 ml, 2.4 mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min, before cyclopropanecarbonyl chloride (46 mg,.4 mmol) was added. The reaction mixture was stirred at 25 C for 20 h and was then quenched with sat. aq. NH 4Cl/NH 3 solution (8:, 5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/et 2O, 9:) yielding 9i as red oil (68 mg, 65%). H NMR (400 MHz, CDCl 3) δ/ppm: 7.3 (s, H), 6.20 (d, J=7.4 Hz, H), 6.06 (d, J=7.4 Hz, H), (m, H), (m, 2 H), 2-0 (m, 2 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 92.6, 35.2, 33.2, 22.3, 9.7, 7.3,.8. IR (Diamond-ATR, neat) ~ /cm - : 3033, 2360, 2086, 645, 56, 528, 438, 48, 385, 292, 98, 6, 28, 090, 06, 029, 984, 925, 878, 792, 78. MS (70 ev, EI) m/z (%): 203 (98), 86 (2), 85 (3), 84 (00), 6 (5), 5 (20), (0), 05 (2), 85 (), 7 (30), 69 (88), 45 (32), 44 (3), 4 (6). HRMS (EI): m/z (M + ) for C 8H 8OS 2: calcd ; found Synthesis of 2-(cyclohex-2-en--yl)-,4-dithiine (9j) S2

13 According to TP,,4-dithiine (; 58 mg, mmol) was dissolved in dry THF ( ml). TMPMgCl LiCl (0 ml, 5 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. ZnCl 2 solution ( ml, mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min. CuCN.2LiCl solution ( ml, mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min, and afterwards, 3-bromocyclohexene (56 mg, 5 mmol) was added. The reaction mixture was stirred at 25 C for 2 h and was then quenched with sat. aq. NH 4Cl/NH 3 solution (8:, 5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 9j as yellow oil (50 mg, 73%). H NMR (300 MHz, CDCl 3) δ/ppm: 6.35 (d, J=6.8 Hz, H), 6.30 (d, J=6.8 Hz, H), 5.92 (s, H), (m, H), (m, H), (m, H), (m, 2 H), (m, H), (m, 2 H), (m, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 42.4, 29.8, 27.7, 23.4, 22.6, 5.6, 42.4, 28.6, 24.9, 2. IR (Diamond-ATR, neat) ~ /cm - : 309, 2926, 2856, 283, 720, 647, 584, 535, 444, 429, 343, 22, 59, 34, 086, 045, 09, 978, 964, 898, 887, 869, 805, 793, 784, 772, 734, 723, 708, 669, 652, 624, 62, 596, 587, 576, 57, 568, 564, 555. MS (70 ev, EI) m/z (%): 96 (20), 79 (23), 77 (2), 53 (34), 52 (22), 45 (00). HRMS (EI): m/z (M + ) for C 0H 2S 2: calcd ; found Synthesis of 2-(,4-dithiin-2-yl)aniline (9k) According to TP,,4-dithiine (;.6 g, 0.0 mmol) was dissolved in dry THF (20 ml). TMPMgCl LiCl (9.9 ml, mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. ZnCl 2 solution (2.0 ml, 2.0 mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min. The freshly prepared zinc reagent was added over h to a solution of 2-iodoaniline (.75 g, 8.0 mmol), Pd(dba) 2 (73 mg, mmol) and P(2-furyl) 3 (39 mg, mmol) in dry THF (7 ml) at 25 C. The reaction mixture was stirred at 25 C for 6 h and was then quenched with sat. aq. NH 4Cl solution (50 ml), extracted with Et 2O (3 x 00 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/etoac, 4:) yielding 9k as yellow oil (.56 g, 94%). H NMR (400 MHz, CDCl 3) δ/ppm: (m, 2 H), (m, 2 H), 6.46 (d, J=6.8 Hz, H), 6.39 (d, J=6.8 Hz, H), 6.20 (s, H), 3.93 (br. s., 2 H). S3

14 3 C NMR (0 MHz, CDCl 3) δ/ppm: 43.9, 35.0, 3, 29.7, 23.0, 22.8, 22.8, 9., 8.5, 6.0. IR (Diamond-ATR, neat) ~ /cm - : 3435, 3352, 3204, 3024, 2923, 2853, 2620, 936, 669, 6, 575, 533, 486, 450, 365, 302, 28, 256, 2, 57, 38, 054, 032, 007, 939, 90, 855, 792, 777, 746, 673, 655, 634, 577, 558. MS (70 ev, EI) m/z (%): 207 (90), 90 (37), 74 (94), 73 (5), 30 (55), 7 (00), 90 (6), 89 (47), 77 (6), 63 (7), 58 (), 57 (), 45 (40), 43 (). HRMS (EI): m/z (M + ) for C 0H 9NS 2: calcd ; found Synthesis of di(,4-dithiin-2-yl)sulfane (9l) According to TP,,4-dithiine (; 348 mg, 2.0 mmol) was dissolved in dry THF (4 ml). TMPMgCl LiCl (2.0 ml, 2.2 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. Bis(phenylsulfonyl)sulfide (20, 34 mg, mmol) in dry THF (2 ml) was added at -78 C and stirred for 2 h allowing to reach 23 C. The resulting solution was then quenched with sat. aq. NH 4Cl solution (0 ml), extracted with EtOAc (3 x 20 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/ch 2Cl 2, 9:) yielding 9l as brown solid (96 mg, 75%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: 6.4 (s, 2 H), (m, 4 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 26.9, 24.2, 22.8, IR (Diamond-ATR, neat) ~ /cm - : 3026, 292, 2850, 680, 573, 52, 276, 26, 25, 34, 090, 020, 883, 82, 769. MS (70 ev, EI) m/z (%): 262 (32), 47 (4), 03 (00), 7 (30), 45 (34), 44 (53). HRMS (EI): m/z (M + ) for C 8H 6S 5: calcd ; found Preparation of difunctionalized,4-dithiine derivatives 2.. Synthesis of,'-(,4-dithiine-2,3-diyl)bis(n,n-dimethylmethanamine) (a) A dry and argon-flushed Schlenk-flask was charged with N,N,N,N - tetramethylmethanediamine (45 mg, 4 mmol) and anydrous CH 2Cl 2 (4 ml). Trifluoroacetic anhydride (92 mg, 4 mmol) was added dropwise and the solution was S4

15 stirred for 5 min at 0 C. 7 In a second dry and argon-flushed Schlenk flask, according to TP2, -(,4-dithiin-2-yl)-N,N-dimethylmethanamine (9e; 69 mg, mmol) was dissolved in dry THF ( ml). TMPMgCl LiCl ( ml, mmol) was added dropwise at -78 C and the reaction mixture was stirred for h. Then, the previously prepared methylene(dimethyl)iminium trifluoroacetate was added at -78 C to the magnesiated - (,4-dithiin-2-yl)-N,N-dimethylmethanamine solution. The reaction mixture was stirred for h at -78 C. The crude mixture was quenched with sat. aq. NaHCO 3 and extracted with EtOAc (3 x 20 ml). The combined organic layers were washed with sat. aq. NaCl and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/etoac, 8:2) yielding a as orange oil (59 mg, 64%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.43 (s, 2 H), 3.7 (s, 4 H), 2.27 (s, 2 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 3.7, 24.3, 6.7, IR (Diamond-ATR, neat) ~ /cm - : 3388, 2973, 294, 2853, 287, 2767, 609, 536, 453, 344, 260, 75, 35, 096, 04, 029, 007, 947, 9, 84, 804, 770, 73, 67. MS (70 ev, EI) m/z (%): 230 (), 85 (00), 4 (2), 40 (47), 29 (), 94 (2), 58 (79), 42 (2). HRMS (EI): m/z (M + ) for C 0H 8N 2S 2: calcd ; found Synthesis of -(3-chloro-,4-dithiin-2-yl)-N,N-dimethylmethanamine (b) According to TP2, -(,4-dithiin-2-yl)-N,N-dimethylmethanamine (9e; 74 mg, 3 mmol) was dissolved in dry THF ( ml). TMPMgCl LiCl (2 ml, 5 mmol) was added dropwise at -78 C and the reaction mixture was stirred for h. hexachloroethane (53 mg, 5 mmol) was added and the resulting solution was stirred for 2 h. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/etoac, 8:2) yielding b as orange oil (38 mg, 43%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.46 (d, J=6.4 Hz, H), 6.40 (d, J=6.4 Hz, H), 3.26 (s, 2 H), 2.28 (s, 6 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 29.9, 24.4, 22.7, 9.2, 62.0, 45.. IR (Diamond-ATR, neat) ~ /cm - : 2974, 2943, 2856, 2820, 2772, 587, 562, 535, 453, 348, 262, 74, 56, 095, 042, 027, 983, 888, 842, 80, 746, 673. MS (70 ev, EI) m/z (%): 209 (9), 207 (23), 7 (4), 58 (00), 55 (5), 45 (5), 44 (7), 4 (5). HRMS (EI): m/z (M + ) for C 7H 0ClNS 2: calcd ; found S5

16 2.3. Synthesis of ethyl 3-iodo-,4-dithiine-2-carboxylate (c) According to TP2, ethyl,4-dithiine-2-carboxylate (9g; 9 g, 5.8 mmol) was dissolved in dry THF (20 ml). TMPMgCl LiCl (5.76 ml, 6.39 mmol) was added dropwise at -78 C and the reaction mixture was stirred for h. The freshly prepared magnesium reagent was added to a solution of iodine (3 g, 4.07 mmol) in dry THF (6 ml) at -78 C. The resulting solution was stirred at this temperature for h and was then quenched with sat. aq. Na 2S 2O 3 solution (50 ml), extracted with Et 2O (3 x 00 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/ch 2Cl 2, 2:) yielding c as orange liquid (793 mg, 62%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.6 (d, J = 6.2 Hz, H), 6.25 (d, J = 6.2 Hz, H), 4.3 (q, J = 7.2 Hz, 2H),.37 (t, J = 7. Hz, 3H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 62.2, 26.6, 24.4, 23.5, 83.2, 62.5, 4.0. IR (Diamond-ATR, neat) ~ /cm - : 3033, 2979, 2934, 70, 60, 558, 50, 463, 443, 388, 365, 22, 3, 093, 030, 889, 85, 795, 76, 676. MS (70 ev, EI) m/z (%): 34 (00), 59 (69), 44 (0), 5 (6), 4 (20), 88 (2), 7 (3), 58 (0), 45 (4). HRMS (EI): m/z (M + ) for C 7H 7O 2IS 2: calcd ; found Synthesis of diethyl,4-dithiine-2,3-dicarboxylate (d) According to TP2, ethyl,4-dithiine-2-carboxylate (9g; 88 mg, mmol) was dissolved in dry THF (2 ml). TMPMgCl LiCl (5 ml, 5 mmol) was added dropwise at -78 C and the reaction mixture was stirred for h. Ethyl cyanoformate (49 mg,.5 mmol) was added and the resulting solution was stirred at this temperature for 3 h. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/etoac, 8:2) yielding d as orange oil (234 mg, 90%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.4 (s, 2 H), 4.28 (q, J=7.2 Hz, 4 H),.33 (t, J=7. Hz, 6 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 62.3, 33.3, 23.8, 62.6, 3.9. IR (Diamond-ATR, neat) ~ /cm - : 3040, 2982, 2938, 2904, 74, 580, 537, 464, 444, 390, 366, 230, 3, 094, 069, 022, 965, 906, 853, 795, 765, 743, 680. S6

17 MS (70 ev, EI) m/z (%): 260 (00), 60 (36), 59 (25), 42 (34), 7 (9), 43 (35). HRMS (EI): m/z (M + ) for C 0H 2O 4S 2: calcd ; found Synthesis of 2,3-diiodo-,4-dithiine (e) According to TP2, 2-iodo-,4-dithiine (a; 242 mg, mmol) was dissolved in dry THF (2 ml). TMPZnCl LiCl (3 ml,. mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. The freshly prepared zinc reagent was added to a solution of iodine (77 mg, mmol) in dry THF ( ml) at -78 C. The resulting solution was stirred at this temperature for h and was then quenched with sat. aq. Na 2S 2O 3 solution (5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding e as yellow solid (75 mg, 68%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: 6.43 (s, 2H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 23.4, IR (Diamond-ATR, neat) ~ /cm - : 3024, 2962, 592, 544, 485, 260, 092, 020, 885, 872, 790, 757, 67. MS (70 ev, EI) m/z (%): 368 (58), 24 (95), 27 (2), 4 (00), 88 (49), 6 (3), 45 (3), 43 (7). HRMS (EI): m/z (M + ) for C 4H 2I 2S 2: calcd : found Synthesis of 2,3-dibromo-,4-dithiine (f) According to TP2, 2-bromo-,4-dithiine (9b; 969 mg, 5.0 mmol) was dissolved in dry THF (0 ml). TMPZnCl LiCl (6.4 ml, 5.5 mmol) was added dropwise at -40 C and the mixture was stirred for h.,2-dibromotetrachloroethane (2.4 g, 7.5 mmol) in dry THF (4mL) was added and the resulting solution was stirred for 2 h and allowed to reach 23 C. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (20 ml), extracted with EtOAc (3 x 50 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by HPLC yielding f as light brown oil (680 mg, 50%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.47 (s, 2 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 23.6, S7

18 IR (Diamond-ATR, neat) ~ /cm - : 3032, 594, 548, 523, 275, 258, 28, 920, 883, 86, 803, 775, 754, 79, 669. MS (70 ev, EI) m/z (%): 276 (23), 274 (33), 95 (78), 93 (64), 4 (38), (29), 97 (33), 95 (63), 9 (58), 85 (39), 83 (47), 82 (29), 8 (27), 7 (67), 69 (57), 67 (28), 57 (00), 56 (27), 55 (64), 44 (55), 43 (62), 4 (5). HRMS (EI): m/z (M + ) for C 4H 2 8 Br 2S 2: calcd ; found Synthesis of 2-allyl-3-bromo-,4-dithiine (g) According to TP2, 2-bromo-,4-dithiine (9b; 36 mg,.6 mmol) was dissolved in dry THF (3 ml). TMPZnCl LiCl (.34 ml,.78 mmol) was added dropwise at -40 C and the reaction mixture was stirred for h. CuCN.2LiCl solution (.94 ml,.94 mmol, M in THF) was added and the reaction mixture was allowed to stir for 5 min, before allyl bromide (37 mg,. mmol) was added. The reaction mixture was stirred at -40 C for h and was then quenched with sat. aq. NH 4Cl/NH 3 solution (8:, 5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding g as yellow liquid (9 mg, 74%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.47 (d, J=6.6 Hz, H), 6.38 (d, J=6.6 Hz, H), 5.77 (ddt, J=6.7,, 6.3, 6.0 Hz, H), (m, 2 H), 3.23 (d, J=6.0 Hz, 2 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 32.0, 32.0, 23.7, 23.4, 7.7, 03.2, 4.5. IR (Diamond-ATR, neat) ~ /cm - : 3032, 308, 2925, 2853, 2832, 78, 648, 585, 563, 556, 520, 500, 492, 466, 433, 43, 34, 275, 24, 80, 62, 33, 090, 053, 029, 02, 979, 966, 95, 899, 885, 865, 822, 798, 780, 778, 74, 730, 705, 668, 654. MS (70 ev, EI) m/z (%): 236 (78), 234 (75), 95 (6), 93 (6), 55 (28), 53 (), 40 (4), 27 (3), 25 (0), 23 (9), 22 (00), 2 (38), (23), 97 (20), 95 (), 85 (4), 83 (4), 8 (0), 7 (22), 69 (32), 57 (28), 55 (6), 45 (27), 44 (4), 43 (28), 4 (2). HRMS (EI): m/z (M + ) for C 7H 7BrS 2: calcd ; found Synthesis of 3-iodo-,4-dithiine-2-carbonitrile (h) According to TP2,,4-dithiine-2-carbonitrile (9d; 93 mg, 6 mmol) was dissolved in dry THF (3 ml). TMPZnCl LiCl (5 ml, 3 mmol) was added dropwise at 0 C and the reaction mixture was stirred for h. The freshly prepared zinc reagent was added to a solution of iodine (7 mg, 6 mmol) in dry THF ( ml) at -78 C. The resulting solution was stirred at this temperature for h and was then quenched with sat. aq. Na 2S 2O 3 S8

19 solution (5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/ch 2Cl 2, 2:) yielding h as orange liquid (06 mg, 86%). H NMR (400 MHz, CDCl 3) δ/ppm: 6.62 (d, J=6.2 Hz, H), 6.3 (d, J=6.2 Hz, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 24.3, 22., 6.0, 09.0, IR (Diamond-ATR, neat) ~ /cm - : 3039, 3028, 2954, 2920, 285, 222, 594, 573, 553, 522, 502, 463, 373, 28, 262, 30, 072, 054, 022, 892, 874, 84, 802, 79, 730, 679, 60, 557. MS (70 ev, EI) m/z (%): 267 (84), 42 (0), 4 (4), 40 (00), 27 (3), 4 (0), 96 (6), 82 (0), 45 (5). HRMS (EI): m/z (M + ) for C 5H 2NIS 2: calcd ; found Synthesis of (3-iodo-,4-dithiin-2-yl)(phenyl)methanone (i) According to TP2, (,4-dithiin-2-yl)(phenyl)methanone (9h; 220 mg, mmol) was dissolved in dry THF (2 ml). TMPZnCl LiCl (3 ml,. mmol) was added dropwise at 0 C and the reaction mixture was stirred for h. The freshly prepared zinc reagent was added to a solution of iodine (78 mg, mmol) in dry THF ( ml) at -78 C. The resulting solution was stirred at this temperature for h and was then quenched with sat. aq. Na 2S 2O 3 solution (5 ml), extracted with Et 2O (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/ch 2Cl 2, 2:) yielding i as orange oil (89 mg, 78%). H NMR (400 MHz, CDCl 3) δ/ppm: 7.88 (d, J=7.8 Hz, 2 H), 7.65 (t, J=7.3 Hz, H), 7.5 (t, J=7.6 Hz, 2 H), 6.66 (d, J=6.4 Hz, H), 6.55 (d, J=6.4 Hz, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 9.2, 34.4, 33.4, 33.0, 30.0, 28.9, 25.9, 22.4, IR (Diamond-ATR, neat) ~ /cm - : 303, 2923, 963, 656, 594, 578, 528, 447, 3, 234, 75, 60, 30, 055, 022, 999, 974, 935, 894, 806, 782, 727, 677. MS (70 ev, EI) m/z (%): 348 (), 347 (3), 346 (98), 220 (3), 29 (4), 9 (6), 90 (25), 47 (2), 05 (00), 77 (72), 5 (26), 43 (45). HRMS (EI): m/z (M + ) for C H 7OIS 2: calcd ; found Preparation of 2,3,5-tribromo-,4-dithiine (2) S9

20 2,3-dibromo-,4-dithiine (g; 23 mg, 8 mmol) was dissolved in dry CH 2Cl 2 (2 ml). Bromine (3 mg, 3 mmol) in dry CH 2Cl 2 (2 ml) and Et 3N (9 ml,.33 mmol) were added dropwise at 0 C. The reaction was stirred for 24 h and allowed to reach 23 C. Then, the reaction mixture was quenched with aq. HCl solution (5.0 ml, 2.0 M) and extracted with CH 2Cl 2 (3 x 0 ml) The combined organic phases were washed with water and brine and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 2 as white solid (230 mg, 84%). m.p.: C H NMR (400 MHz, CDCl 3) δ/ppm: 6.52 (s, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 22.0,,, IR (Diamond-ATR, neat) ~ /cm - : 3035, 2358, 553, 532, 59, 222, 206, 94, 97, 860, 809, 776, 757, 720, 72. MS (70 ev, EI) m/z (%): 356 (2), 354 (7), 352 (6), 350 (2), 275 (0), 273 (9), 27 (9), 94 (), 92 (), 6 (6), 45 (5), 44 (2), 43 (00), 4 (5). HRMS (EI): m/z (M + ) for C 4H 79 Br 3S 2: calcd ; found Preparation of perbromo-,4-dithiine (3) 2,3,5-Tribromo-,4-dithiine (2; 57 mg,.5 mmol) was dissolved in dry THF (9 ml). TMPZnCl LiCl (.8 ml,.6 mmol) was added dropwise at -78 C and the mixture was stirred for 5 min.,2-dibromotetrachloroethane (723 mg, 2.2 mmol) in dry THF ( ml) was added and the resulting solution was allowed to reach 23 C for 24 h, after which time it was warmed to 50 C and stirred for further 2 h.. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 3 as white solid (357 mg, 56%). m.p.: C NMR (0 MHz, CDCl 3) δ/ppm:. IR (Diamond-ATR, neat) ~ /cm - : 3078, 3028, 292, 285, 64, 593, 556, 530, 54, 423, 407, 265, 08, 047, 985, 937, 94, 884, 848, 830, 798, 769, 676. S20

21 MS (70 ev, EI) m/z (%): 434 (8), 432 (25), 430 (8), 355 (35), 353 (00), 35 (94), 349 (29), 274 (36), 272 (69), 270 (32), 49 (24), 47 (23), 37 (3), 35 (29), 88 (39), 68 (30). HRMS (EI): m/z (M + ) for C 4 79 Br 4S 2: calcd ; found Preparation of monosubstituted,4,5,8-tetrathianaphthalene 5.. Synthesis of 2-iodo-[,4]dithiino[2,3-b][,4]dithiine (4a) According to TP3,,4,5,8-tetrathianaphthalene (4; 02 mg, mmol) was dissolved in dry THF (4 ml). TMPMgCl LiCl ( ml, mmol) was added dropwise at -78 C and the mixture was stirred for 0 min. Iodine (9 mg, 5 mmol) in dry THF ( ml) was added and the resulting solution was stirred at this temperature for 2 h. Then, the reaction mixture was quenched with sat. aq. Na 2S 2O 3 solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 4a as yellow solid (47 mg, 89%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: 6.70 (s, H), 6.47 (d, J=6.6 Hz, H), 6.44 (d, J=6.6 Hz, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 29.4, 25.7, 25.6, 2, 2, IR (Diamond-ATR, neat) ~ /cm - : 3025, 2926, 607, 568, 533, 50, 470, 366, 260, 23, 28, 965, 906, 887, 864, 834, 80, 778, 759, 733. MS (70 ev, EI) m/z (%): 330 (86), 285 (4), 203 (78), 59 (00), 46 (46), 27 (32), 88 (69), 69 (48), 57 (36), 45 (55). HRMS (EI): m/z (M + ) for C 6H 3IS 4: calcd ; found Synthesis of 2-bromo-[,4]dithiino[2,3-b][,4]dithiine (4b) According to TP3,,4,5,8-tetrathianaphthalene (4; 02 mg, mmol) was dissolved in dry THF (4 ml). TMPMgCl LiCl ( ml, mmol) was added dropwise at -78 C and the mixture was stirred for 0 min.,2-dibromotetrachloroethane (244 mg, 5 mmol) in dry THF ( ml) was added and the resulting solution was stirred at this temperature for 2 h. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 4b as yellow solid (26 mg, 89%). S2

22 m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: 6.53 (s, H), (m, 2 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 25.9, 25.6, 23.8, 2.8, 9.6, 2.8. IR (Diamond-ATR, neat) ~ /cm - : 3032, 2923, 55, 538, 57, 280, 263, 208, 35, 966, 904, 870, 850, 804, 782, 759, 70, 673. MS (70 ev, EI) m/z (%): 284 (67), 282 (60), 239 (47), 237 (44), 203 (86), 59 (00), 27 (54), 88 (79), 69 (40), 45 (5). HRMS (EI): m/z (M + ) for C 6H 3 8 BrS 4: calcd ; found Synthesis of [,4]dithiino[2,3-b][,4]dithiine-2-carbonitrile (4c) According to TP3,,4,5,8-tetrathianaphthalene (4; 02 mg, mmol) was dissolved in dry THF (4 ml). TMPMgCl LiCl ( ml, mmol) was added dropwise at -78 C and the mixture was stirred for 0 min. 4-Tolylsulfonyl cyanide (36 mg, 5 mmol) in dry THF ( ml) was added and the resulting solution was stirred for 2 h allowing to reach 23 C. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/etoac, 96:4) yielding 4c as orange solid (84 mg, 73%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: 7.3 (s, H), 6.49 (d, J=6.4 Hz, H), 6.46 (d, J=6.4 Hz, H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 43.3, 25.7, 25.2, 20.0, 8.6, 3.7, IR (Diamond-ATR, neat) ~ /cm - : 3027, 2222, 578, 559, 543, 506, 28, 263, 23, 9, 099, 062, 966, 885, 862, 852, 803, 767, 678. MS (70 ev, EI) m/z (%): 23 (4), 229 (20), 96 (4), 86 (4), 84 (29), 65 (8), 59 (8), 53 (6), 02 (6), 88 (0), 76 (7), 73 (4), 70 (8), 6 (4), 45 (3), 43 (00), 42 (5). HRMS (EI): m/z (M + ) for C 7H 3NS 4: calcd ; found Synthesis of 2-(methylthio)-[,4]dithiino[2,3-b][,4]dithiine (4d) According to TP3,,4,5,8-tetrathianaphthalene (4; 4 mg, mmol) was dissolved in dry THF (.6 ml). TMPMgCl LiCl ( ml, 4 mmol) was added dropwise at -78 C S22

23 and the mixture was stirred for 0 min. S-Methyl thiomethanesulfonate (38 mg, mmol) was added and the resulting solution was stirred for 2 h allowing to reach 23 C. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane) yielding 4d as light yellow solid (39 mg, 78%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: (m, 2 H), 6.08 (s, H), 2.40 (s, 3 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 39.0, 25.6, 25.6, 23.4, 9.9, 6.2, 8.. IR (Diamond-ATR, neat) ~ /cm - : 309, 2977, 290, 2850, 575, 556, 539, 5, 47, 429, 4, 30, 264, 229, 34, 968, 95, 904, 888, 857, 798, 766, 735. MS (70 ev, EI) m/z (%): 250 (2), 59 (0), 70 (3), 6 (7), 45 (5), 43 (00). HRMS (EI): m/z (M + ) for C 7H 6S 5: calcd ; found Synthesis of ethyl [,4]dithiino[2,3-b][,4]dithiine-2-carboxylate (4e) According to TP3,,4,5,8-tetrathianaphthalene (4; 62 mg, 3.0 mmol) was dissolved in dry THF (24 ml). TMPMgCl LiCl (3.3 ml, 3.6 mmol) was added dropwise at -78 C and the mixture was stirred for 0 min. Ethyl cyanoformate (446 mg, 4.5 mmol) was added and the resulting solution was stirred for 2 h allowing to reach 23 C. Then, the reaction mixture was quenched with sat. aq. NH 4Cl solution (5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/ch 2Cl 2, 8:2 to 7:3) yielding 4e as orange solid (600 mg, 72%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: 7.45 (s, H), 6.49 (d, J=6.6 Hz, H), 6.44 (d, J=6.6 Hz, H), 4.25 (q, J=7. Hz, 2 H),.32 (t, J=7. Hz, 3 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 6, 36.7, 3, 25.8, 25.0, 2, 6.8, 62.3, 4.. IR (Diamond-ATR, neat) ~ /cm - : 3033, 2979, 704, 572, 552, 463, 443, 39, 366, 263, 244, 28, 094, 040, 997, 886, 856, 828, 805, 770, 73, 677. MS (70 ev, EI) m/z (%): 295 (20), 276 (00), 23 (76), 22 (43), 207 (25), 203 (88), 59 (80), 47 (22), 46 (35), 03 (2), 9 (25), 88 (46), 85 (24), 8 (20), 76 (3), 7 (3), 70 (22), 69 (4), 69 (27), 57 (55), 55 (27), 44 (60), 43 (32), 40 (26). HRMS (EI): m/z (M + ) for C 9H 8O 2S 4: calcd ; found S23

24 5.6. Synthesis of [,4]dithiino[2,3-b][,4]dithiin-2- yl(cyclopropyl)methanone (4f) According to TP3,,4,5,8-tetrathianaphthalene (4; 02 mg, mmol) was dissolved in dry THF (4 ml). TMPMgCl LiCl ( ml, mmol) was added dropwise at -78 C and the mixture was stirred for 0 min. CuCN 2LiCl ( ml, mmol, M in THF) was then introduced followed by cyclopropanecarbonyl chloride (78 mg, 5 mmol) and the reaction warmed to 40 ºC and stirring was continued for a further 8 h. Then, the reaction mixture was quenched with sat. aq. NH 4Cl/NH 3 solution (8:, 5 ml), extracted with EtOAc (3 x 0 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. The crude product was purified by flash column chromatography on silica gel (ihexane/etoac, 96:4) yielding 4f as dark red solid (89 mg, 65%). m.p.: C. H NMR (400 MHz, CDCl 3) δ/ppm: 7.48 (s, H), 6.50 (d, J=6.4 Hz, H), 6.44 (d, J=6.6 Hz, H), (m, H),. -.2 (m, 2 H), 5-6 (m, 2 H). 3 C NMR (0 MHz, CDCl 3) δ/ppm: 92.5, 39.7, 35.6, 25.9, 24.8, 2, 6.8, 7.6, 2.3. IR (Diamond-ATR, neat) ~ /cm - : 307, 3042, 303, 3004, 2954, 2923, 2853, 627, 574, 558, 542, 523, 463, 435, 47, 397, 322, 276, 262, 222, 204, 73, 27, 095, 087, 057, 030, 959, 923, 890, 878, 847, 838, 827, 8, 800, 783, 769, 732, 79, 69, 674. MS (70 ev, EI) m/z (%): 272 (00), 227 (63), 59 (59), 46 (9), 88 (2). HRMS (EI): m/z (M + ) for C 0H 8OS 4: calcd ; found Preparation of disubstituted,4,5,8-tetrathianaphthalene 6.. Synthesis of 2-iodo-3-allyl-[,4]dithiino[2,3-b][,4]dithiine (5a) According to TP4, 2-iodo-[,4]dithiino[2,3-b][,4]dithiine (4a; 99 mg, mmol) was dissolved in dry THF (2.4 ml). TMPZnCl LiCl ( ml, 3 mmol) was added dropwise at -40 C and the mixture was stirred for h. CuCN 2LiCl (0.06 ml, 0.06 mmol, M in THF) was then introduced followed by allyl bromide (54 mg, 5 mmol) and the reaction was stirred for 2 h allowing to reach 23 C. Then, the reaction mixture was quenched with sat. aq. NH 4Cl/NH 3 solution (8:, 5 ml), extracted with EtOAc (3 x 5 ml) and dried over anhydrous Na 2SO 4. After filtration, the solvents were evaporated in vacuo. S24