Supporting Information Copyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, 2013 Tuning the Lewis Acidity of Boranes in rustrated Lewis Pair Chemistry: Implications for the Hydrogenation of Electron-Poor Alkenes Juan A. Nicasio, Sebastian Steinberg, Blanca InØs, and Manuel Alcarazo* [a] chem_201301158_sm_miscellaneous_information.pdf
Table of Contents Experimental Procedures Characterization of new compounds NMR spectra X-ray structure analysis Evaluation of the relative Lewis acidity of boranes S2 S2 S11 S24 S25 1
General procedures: All reactions were carried out in flame-dried glassware under Ar. All the solvents were purified by distillation over the drying agents indicated and were transferred under Ar. CH 2 Cl 2 (CaH 2 ), hexane and toluene (Na/K). lash chromatography: Merck silica gel 60 (230-400 mesh). IR: Nicolet T-7199 spectrometer, wavenumbers in cm 1. MS (EI): innigan MAT 8200 (70 ev), ESI-MS: innigan MAT 95, accurate mass determinations: Bruker APEX III T-MS (7 T magnet). NMR: Spectra were recorded on a Bruker DPX 300 or AV 400 spectrometer in the solvents indicated; 1 H and 13 C chemical shifts (δ) are given in ppm relative to TMS, coupling constants (J) in Hz. The solvent signals were used as references and the chemical shifts converted to the TMS scale. All commercially available compounds (Acros, luka, Lancaster, Alfa Aesar, Aldrich) were used as received unless stated otherwise. General procedure for the synthesis of tris(fluorophenyl)boranes: The corresponding di- or trifluoro-substituted bromobenzene (3 eq.) was dissolved in freshly distilled TH (0.05 M) and cooled to -20 C. At this temperature i-prmgcl (3 eq., 2.0 M in Et 2 O) was added dropwise. The reaction mixture was then allowed to reach 0 C and after 1 h at this temperature cooled again to -50 C. Subsequently, B 3 Et 2 O (1 eq.) was added dropwise and after 1 h the cooling bath was removed and the reaction mixture warmed to room temperature within another hour. Removal of all volatiles and sublimation of the remaining solid (120 C, 1 10-3 mbar) afforded the desired boranes as white solids. Compound 4: Prepared following the general procedure from 1-bromo-2,4,6- B trifluorobenzene (0.57 ml, 4.8 mmol), i-prmgcl (2.0 M in Et 2 O, 2.4 ml, 4.8 mmol) and B 3 Et 2 O (0.20 ml, 1.6 mmol). White solid (550 mg, 85%). 1 H NMR (300 MHz, CD 2 Cl 2 ) δ = 6.68 (dd, J = 8.9, 8.0 Hz, 6H) ppm. 13 C NMR (75 MHz, CD 2 Cl 2 ) δ = 100.8 (ddd, J = 30.2, 25.0, 3.2 Hz), 166.5 (dt, J = 252.2, 14.9 Hz), 167.1 (dt, J = 255.1, 16.8 Hz) ppm. 11 B NMR (96 MHz, CD 2 Cl 2 ) δ = 59.4 ppm. 19 NMR (282 MHz, CD 2 Cl 2 ) δ = -100.9 (t, J = 10.1 Hz, 3), -96.4 (d, J = 9.9 Hz, 6) ppm. 2
IR (neat) v ~ = 720, 838, 875, 891, 998, 1022, 1113, 1164, 1224, 1291, 1326, 1412, 1424, 1479, 1518, 1579, 1602, 1629, 3112 cm -1. HRMS calcd. for C 18 H 6 B 9 : 404.041883; found: 404.041906. Compound 5: Prepared following the general procedure from 1-bromo-2,4,5- B trifluorobenzene (0.50 ml, 4.2 mmol), i-prmgcl (2.0 M in Et 2 O, 2.1 ml, 4.2 mmol) and B 3 Et 2 O (0.18 ml, 1.4 mmol). White solid (425 mg, 75%). 1 H NMR (300 MHz, CD 2 Cl 2 ) δ = 6.97-7.05 (m, 3H), 7.16 (dt, J = 9.8, 5.5 Hz, 3H) ppm. 13 C NMR (75 MHz, CD 2 Cl 2 ) δ = 106.3 (dd, J = 31.6, 20.3 Hz), 125.5 (ddd, J = 17.6, 9.0, 2.1 Hz), 147.4 (ddd, J = 246.0, 12.1, 3.4 Hz), 154.1 (dt, J = 257.9, 14.1 Hz), 162.6 (ddd, J = 250.7, 9.7, 2.1 Hz) ppm. 11 B NMR (96 MHz, CD 2 Cl 2 ) δ = 61.8 ppm. 19 NMR (282 MHz, CD 2 Cl 2 ) δ = -143.9 (dd, J = 22.1, 15.7 Hz, 3), -126.0 (dd, J = 22.1, 8.8 Hz, 3), -100.4 (dd, J = 15.8, 8.6 Hz, 3) ppm. IR (neat) v ~ = 681, 719, 746, 778, 815, 893, 1040, 1085, 1128, 1140, 1183, 1193, 1276, 1298, 1393, 1419, 1491, 1618, 3080, 3476, 3547 cm -1. HRMS calcd. for C 18 H 6 B 9 : 404.041883; found: 404.041715. Compound 6: Prepared following the general procedure from 1-bromo-2,6- B difluorobenzene (1.0 ml, 8.8 mmol), i-prmgcl (2.0 M in Et 2 O, 4.4 ml, 8.8 mmol) and B 3 Et 2 O (0.37 ml, 2.9 mmol). White solid (609 mg, 59%). 1 H NMR (300 MHz, CD 2 Cl 2 ) δ = 6.91 (t, J = 8.2 Hz, 6H), 7.46-7.56 (m, 3H) ppm. 13 C NMR (75 MHz, CD 2 Cl 2 ) δ = 111.6 (dd, J = 26.5, 1.7 Hz), 135.5 (t, J = 11.6 Hz), 165.5 (dd, J = 250.5, 11.9 Hz) ppm. 11 B NMR (96 MHz, CD 2 Cl 2 ) δ = 63.6 ppm. 19 NMR (282 MHz, CD 2 Cl 2 ) δ = -99.8 ppm. IR (neat) v ~ = 699, 732, 780, 871, 966, 1120, 1169, 1211, 1239, 1283, 1316, 1439, 1558, 1614, 3503 cm -1. HRMS calcd. for C 18 H 9 B 6 : 350.070153; found: 350.070229. 3
Compound 7: Prepared following the general procedure from 1-bromo-2,4- B difluorobenzene (1.0 ml, 8.8 mmol), i-prmgcl (2.0 M in Et 2 O, 4.4 ml, 8.8 mmol) and B 3 Et 2 O (0.37 ml, 2.9 mmol). White solid (408 mg, 41%). 1 H NMR (300 MHz, CD 2 Cl 2 ) δ = 6.86 (dt, J = 9.5, 2.3 Hz, 3H), 6.97 (dt, J = 8.3, 2.4 Hz, 3H), 7.36 (q, J = 7.8 Hz, 3H) ppm. 13 C NMR (75 MHz, CD 2 Cl 2 ) δ = 104.1 (dd, J = 29.2, 24.5 Hz), 111.7 (dd, J = 20.4, 3.3 Hz), 140.4 (t, J = 9.8 Hz), 165.6 (dd, J = 74.2, 12.7 Hz), 169.0 (dd, J = 72.5, 12.6 Hz) ppm. 11 B NMR (96 MHz, CD 2 Cl 2 ) δ = 63.0 ppm. 19 NMR (282 MHz, CD 2 Cl 2 ) δ = -104.1 (d, J = 11 Hz, 3), -95.7 (d, J = 11 Hz, 3) ppm. IR (neat) v ~ = 674, 712, 732, 742, 815, 849, 968, 1081, 1090, 1113, 1136, 1227, 1248, 1289, 1402, 1495, 1575, 1596, 3075 cm -1. HRMS calcd. for C 18 H 9 B 6 : 350.070154; found: 350.070459. Alkylidene disulfones, 1 sulfonoesters 2 and nitroalkenes 3 were prepared accordingly to the procedures described in the literature. The spectroscopic and analytic characterization of those not reported follows: Compound 19: 1 H NMR (300 MHz, CDCl 3 ) δ = 1.11 (t, J = 7.1 Hz, 3H), 4.19 (q, J = 7.1 O O O S Ph O 3 C Hz, 2H), 7.55 (t, J = 7.8 Hz, 4H), 7.60-7.68 (m, 3H), 7.96 (d, J = 7.5 Hz, 2H), 8.01 (s, 1H) ppm. 13 C NMR (75 MHz, CDCl 3 ) δ = 13.6, 62.9, 123.6 (q, J = 268.6 Hz), 125.5, 125.8 (q, J = 3.8 Hz), 128.7, 129.2, 129.9, 132.7 (q, J = 32.8 Hz), 134.0, 135.3, 135.3, 137.8, 139.6, 142.0, 162.5 ppm. 19 NMR (282 MHz, CDCl 3 ) δ = -63.1 ppm. IR (neat) v ~ = 685, 730, 830, 909, 1016, 1067, 1086, 1115, 1151, 1217, 1320, 1373, 1448, 1623, 1724, 2988 cm -1. HRMS calcd. for C 18 H 15 3 O 4 S: 407.053534; found: 407.053511. 1 a) S. Sulzer-Mossé, A. Alexakis, J. Mareda, G. Bollot, G. Bernardinelli, Y. ilinchuk, Chem. Eur. J. 2009, 15, 3204-3220; b) H. Asahara, H. Mayr, Chem. Asian J. 2012, 7, 1401-1407 2 D. A. R. Happer, B. E. Steenson, Synthesis, 1980, 806-807. 3 a) P. J. Black, G. Cami-Kobeci, M. G. Edwards, P. A. Slatford, M. K. Whittlesey, J. M. J. Williams, Org. Biomol. Chem. 2006, 116-125; b) S. Cai, X. Zhao, X. Wang, Q. Liu, Z Li, D. Z. Wan, Angew. Chem. Int. Ed. 2012, 51, 8050-8053 4
Compound 22: 1 H NMR (400 MHz, CD 2 Cl 2 ) δ = 7.32-7.39 (m, 2H), 7.42-7.54 (m, 4H), O O O O S S Ph Ph 3 C 7.54-7.60 (m, 1H), 7.69 (dd, J = 16.4, 8.3 Hz, 4H), 7.77-7.84 (m, 1H), 8.10 (dd, J = 8.4, 1.2 Hz, 2H), 8.73 (s, 1H) ppm. 13 C NMR (101 MHz, CD 2 Cl 2 ) δ = 124.6 (q, J = 263.0 Hz), 125.6 (q, J = 3.7 Hz), 128.5, 129.4, 129.6, 129.8, 130.0, 134.8, 134.9, 135.1, 132.6 (q, J = 31.6 Hz), 139.9, 140.5, 147.8, 150.7 ppm. 19 NMR (376 MHz, CD 2 Cl 2 ) δ = -63.3 ppm. IR (neat) v ~ = 658, 683, 719, 739, 753, 832, 945, 999, 1018, 1065, 1081, 1110, 1124, 1149, 1319, 1408, 1448, 1479, 1595, 3007, 3071 cm -1. HRMS calcd. for C 21 H 15 3 O 4 S 2 Na: 475.025608; found: 475.025730. Reduction products: All nitroalkanes obtained after reduction of the corresponding nitroolefines were known products. 4 Compound 26: After hydrogenation following the general procedure it was purified by O O O S O Ph flash chromatography (SiO 2 ; hexanes : ethyl acetate, 6:1) to afford a colourless oil (64 mg, 97%). 1 H NMR (400 MHz, CDCl 3 ) δ = 0.99 (t, J = 7.1 Hz, 3H), 3.23 (dd, J = 16.5, 9.0 Hz, 1H), 3.42 (dd, J = 13.6, 3.4 Hz, 1H), 3.97 (qd, J = 7.1, 2.8 Hz, 2H), 4.20 (dd, J = 11.9, 3.5 Hz, 1H), 7.09-7.16 (m, 2H), 7.18-7.31 (m, 4H), 7.55-7.64 (m, 2H), 7.66-7.76 (m, 1H), 7.90-7.99 (m, 2H) ppm. 13 C NMR (101 MHz, CDCl 3 ) δ = 12.8, 31.7, 61.3, 71.3, 126.4, 127.9, 128.0, 128.3, 128.5, 133.5, 134.7, 136.33, 164.41 ppm. IR (neat) v ~ = 699, 722, 749, 800, 849, 1024, 1083, 1144, 1196, 1228, 1260, 1322, 1369, 1447, 1369, 1447, 1495, 1585, 1603, 1736, 2936, 2983, 3027, 3063 cm -1. HRMS calcd. for C 17 H 18 O 4 SNa: 341.081805; found: 341.081546. Compound 27: After hydrogenation following the general procedure it was purified by O O O S O Ph flash chromatography (SiO 2 ; hexanes : ethyl acetate, 6:1) to afford a colourless oil (57 mg, 97%). 1 H NMR (300 Mz, CDCl 3 ) δ = 1.00 (t, J = 7.1 Hz, 3H), 3.25-3.39 C 3 (m, 1H), 3.49 (dd, J = 13.7, 3.5 Hz, 1H), 3.98 (q, J = 6.1 Hz, 2H), 4 S. Cai, X. Zhao, X. Wang, Q. Liu, Z. Li, D. Z. Wang, Angew. Chem. Int. Ed. 2012, 51, 8050. 5
4.20 (dd, J = 11.6, 3.7 Hz, 1H), 7.28 (d, J = 8.3 Hz, 2H), 7.48-7.67 (m, 4H), 7.73 (t, J = 7.4 Hz, 1H), 7.89-8.01 (m, 2H) ppm. 13 C NMR (75 MHz, CDCl 3 ) δ = 13.8, 32.4, 62.5, 71.9, 125.9 (q, J = 3.7 Hz), 129.3, 129.5, 129.6, 129.9 (q, J = 33.4 Hz), 134.6, 137.3, 140.0, 165.1 ppm. (C 3 signal not observed). 19 NMR (282 MHz, CDCl 3 ) δ = -62.9 ppm. IR (neat) v ~ = 687, 721, 737, 758, 825, 852, 876, 1018, 1066, 1083, 1109, 1121, 1145, 1194, 1231, 1260, 1321, 1370, 1419, 1448, 1585, 1618, 1735, 2986, 3070 cm -1. HRMS calcd. for C 18 H 17 3 O 4 SNa: 409.069186; found: 409. 068888. Compound 28: After hydrogenation following the general procedure it was purified by O O O S O Ph OMe flash chromatography (SiO 2 ; hexanes : ethyl acetate, 6:1) to afford a colourless oil (48 mg, 65%). 1 H NMR (400 MHz, CDCl 3 ) δ = 0.99 (t, J = 7.1 Hz, 3H), 3.17 (dd, J = 13.6, 12.0 Hz, 1H), 3.35 (dd, J = 13.7, 3.5 Hz, 1H), 3.96 (q, J = 7.1 Hz, 2H), 3.75 (s, 3H), 4.15 (dd, J = 11.9, 3.5 Hz, 1H), 6.72-6.84 (m, 2H), 7.00-7.09 (m, 2H), 7.53-7.64 (m, 2H), 7.64-7.75 (m, 1H), 7.86-7.98 (m, 2H) ppm. 13 C NMR (101 MHz, CDCl 3 ) δ = 13.8, 31.9, 55.3, 62.2, 72.5, 114.3, 127.5, 129.2, 129.5, 130.0, 134.4, 137.3, 158.9, 165.43 ppm. IR (neat) v ~ = 688, 722, 735, 753, 822, 852, 874, 1031, 1083, 1110, 1144, 1178, 1196, 1248, 1310, 1321, 1369, 1391, 1447, 1465, 1512, 1584, 1612, 1734, 2383, 2937, 2984, 3067 cm -1. HRMS calcd. for C 18 H 20 O 5 S: 371.092363; found: 371.092279. Compound 29: After hydrogenation following the general procedure it was purified by O O O O flash chromatography (SiO 2 ; hexanes : ethyl acetate, 2:1) to afford a Ph S S Ph crystalline white solid (74.5 mg, 98%). 1 H NMR (400 MHz, CD 2 Cl 2 ) δ = 3.51 (d, J = 5.8 Hz, 2H), 4.78 (t, J = 5.8 Hz, 1H), 6.98-7.00 (m, 2H), 7.16-7.20 (m, 3H), 7.51-7.55 (m, 4H), 7.66-7.71 (m, 2H), 7.81-7.84 (m, 4H) ppm. 13 C NMR (101 MHz, CD 2 Cl 2 ) δ = 31.6, 85.2, 127.5, 129.0, 129.6, 129.7, 135.0, 136.6, 138.6 ppm. IR (neat) v ~ = 685, 697, 710, 727, 737, 755, 764, 777, 806, 838, 854, 899, 928, 997, 1006, 1022, 1077, 1141, 1152, 1178, 1205, 1265, 1306, 1318, 1327, 1345, 1446, 1455, 1479, 1497, 1584, 1604, 2929, 3030, 3064 cm -1. 6
HRMS calcd. for C 20 H 18 O 4 S 2 Na: 409.053872; found: 409.054162. Compound 30: After hydrogenation following the general procedure it was purified by O O O O S S Ph Ph 3 C flash chromatography (SiO 2 ; hexanes : ethyl acetate, 2:1) (88 mg, 95%). 1 H NMR (300 MHz, CDCl 3 ) δ = 3.60 (d, J = 5.5 Hz, 2H), 4.72 (t, J = 5.6 Hz, 1H), 7.18 (d, J = 7.9 Hz, 2H), 7.48 (d, J = 11.6 Hz, 2H), 7.53 (d, J = 7.7 Hz 4H), 7.66 (d, J = 7.4 Hz, 2H), 7.85 (d, J = 7.7 Hz, 4H) ppm. 13 C NMR (75 MHz, CDCl 3 ) δ = 31.3, 85.0, 124.1 (J = 262.2 Hz), 125.8 (q, J = 3.8 Hz), 129.3, 129.4, 129.6, 129.8 (q, J = 36.6 Hz), 134.9, 138.1, 140.5 ppm. 19 NMR (282 MHz, CDCl 3 ) δ = -62,7 ppm. IR (neat) v ~ = 686, 736, 758, 787, 823, 853, 911, 999, 1019, 1067, 1078, 1122, 1155, 1260, 1323, 1420, 1448, 1584, 1619, 1708, 2931, 3071 cm -1. HRMS calcd. for C 21 H 17 3 O 4 S 2 Na: 477.041262; found: 477.041384 Compound 31: After hydrogenation following the general procedure it was purified by O O O O S S Ph Ph O flash chromatography (SiO 2 ; hexanes : ethyl acetate, 2:1) (82 mg, 96%). 1 H NMR (400 MHz, CDCl 3 ) δ = 3.48 (d, J = 5.5 Hz, 2H), 3.76 (s, 3H), 4.69 (t, J = 5.5 Hz, 1H), 6.71 (d, J = 8.7 Hz, 2H), 6.94 (d, J = 8.6 Hz, 2H), 7.52 (t, J = 7.8 Hz, 4H), 7.66 (t, J = 7.5 Hz, 2H), 7.86 (dd, J = 8.3, 1.0 Hz, 4H) ppm. 13 C NMR (101 MHz, CDCl 3 ) δ = 30.7, 55.4, 85.6, 114.2, 128.3, 129.2, 129.6, 129.9, 134.6, 138.4, 158.8 ppm. IR (neat) v ~ = 724, 756, 793, 821, 850, 907, 998, 1032, 1078, 1109, 1148, 1178, 1247, 1311, 1325, 1447, 1478, 1513, 1584, 1612, 2257, 2837, 2963, 3007, 3067 cm -1. HRMS calcd. for C 21 H 20 O 5 S 2 Na: 439.064436; found: 439.064528. Compound 38: After hydrogenation following the general procedure it was purified by NO 2 flash chromatography (SiO 2 ; hexanes : ethyl acetate, 6:1) to afford a colourless oil (35.5 mg, 95%). 1 H NMR (400 MHz, CDCl 3 ) δ = 3.31 (t, J = 7.3 Hz, 2H), 4.63 (t, J = 7.3 Hz, 2H), 7.01-7.65 (m, 5H) ppm. 13 C NMR (101 MHz, CDCl 3 ) δ = 33.9, 76.9, 127.9, 129.1, 129.4, 136.6 ppm. 7
IR (neat) v ~ = 697, 750, 862, 907, 1030, 1083, 1183, 1223, 1377, 1431, 1455, 1496, 1547, 2923, 3031 cm -1. HRMS calcd. for C 8 H 9 NO 2 : 151.063331; found: 151.063262. 8
Deuterium labelling experiments: Synthesis of [ t Bu 3 PH][DB(2,4,6--Ph) 3 ]: A solution of t Bu 3 P (0.45 ml, 0.9 mmol, 2.0 M in toluene) was added to a stirring solution of 360 mg (0.9 mmol) of tris(2,4,6-trifluorophenyl)borane in tbu H 9.1 ml of toluene (0.1 M). Bubbling of D 2 to the P tbu B D clear solution immediately forms a white precipitate. tbu The volume of the resulting suspension was then reduced to the half and 6 ml of n-pentane are added. After removing of the solvent by filtration, the residue is washed twice with 6 ml n-pentane and further purified by column chromatography affording (SiO 2 ; CH 2 Cl 2 ) 155 mg (30%) of [ t Bu 3 PH][DB(2,4,6--Ph) 3 ] as a white solid. 1 H NMR (300 MHz, CD 3 CN) δ = 1.60 (d, J = 15.5 Hz, 27H), 5.40 (d, J = 443.7 Hz, 1H), 6.39 (dd, J = 9.5, 7.1 Hz, 6H) ppm. 13 C NMR (75 MHz, CD 3 CN) δ = 30.3, 98.5 (dd, J = 36.6, 37.3 Hz), carbon atoms directly attached to were not observed. 11 B NMR (96 MHz, CD 2 Cl 2 ) δ = -25.6 ppm. 19 NMR (282 MHz, CD 2 Cl 2 ) δ = -119.9, -99.8 ppm. 31 P NMR (122 MHz, CD 2 Cl 2 ) δ = 57.1 ppm. IR (neat) v ~ = 674, 739, 809, 890, 934, 942, 994, 1031, 1101, 1156, 1177, 1206, 1281, 1309, 1321, 1380, 1401, 1436, 1463, 1473, 1484, 1514, 1582, 1617, 1689, 1764, 2922, 2980, 3004, 3085 cm -1. ESI MS(pos.) [ t Bu 3 PH] + = 203 m/z. ESI MS(neg.) [DB(2,4,6--Ph) 3 ] - = 406 m/z. HRMS calcd. for C 18 H 6 DB 9 : 406.056535; found: 406.056621. Synthesis of K[DB(2,4,6--Ph) 3 ]: A solution of [ t Bu 3 PH][DB(2,4,6--Ph) 3 ] (188 mg, 0.31 K D B mmol) in TH (10 ml) was treated with KH (19 mg, 0.47 mmol) and the resulting suspension stirred for 1 hour at r.t. iltration afforded a transparent solution that was evaporated in vacuum. The white precipitate thus obtained was washed with pentane (4 x 4 ml) and dried in vacuum affording the desired salt (110 mg, 80%). 1 H NMR (300 MHz, CD 3 CN) δ = 6.40 (dd, J = 9.6, 7.2 Hz, 6H) ppm. 11 B NMR (96 MHz, CD 2 Cl 2 ) δ = -26.1 ppm. 9
19 NMR (282 MHz, CD 2 Cl 2 ) δ = -120.6, -100.2 (t, J = 3.4 Hz) ppm. Synthesis of [HDABCO][DB(2,4,6--Ph) 3 ]: A solution of 35 mg DABCO HCl in N D N H B acetonitrile (5.0 ml) was added dropwise under argon to a stirring solution of K[DB(2,4,6--Ph) 3 ] (100 mg, 0.23 mmol) in acetonitrile (2.3 ml, 0.1 M) and stirred over night. The resulting suspension was filtered off, the filtrate evaporated and the residue washed three times with n- pentane (5 ml). The white solid thus obtained was dried under high vacuum affording 88 mg (74%) of [HDABCO][DB(2,4,6--Ph) 3 ]. 1 H NMR (300 MHz, CD 3 CN) δ = 3.05 (s, 12H), 6.41 (dd, J = 9.5, 7.1 Hz, 6H), 7.37 (br s, 1H) ppm; 13 C NMR (75 MHz, CD 3 CN) δ = 45.5, 98.5 (dd, J = 37.0, 36.3 Hz), 161.1 (dt, J = 238.2 Hz, 17.1 Hz), 167.4 (dm, J = 239.1 Hz); 1 B NMR (96 MHz, CD 3 CN) δ = -26.0 ppm; 19 NMR (282 MHz, CD 3 CN) δ = -120.6, -100.2 ppm; IR (neat) v ~ = 669, 688, 745, 760, 785, 835, 870, 992, 1054, 1101, 1159, 1281, 1321, 1406, 1464, 1515, 1583, 1620, 1697, 1777, 2983, 3094 cm -1 ; ESI(pos.) [HDABCO] + = 113 m/z; ESI(neg.) [DB(2,4,6--Ph) 3 ] - = 406 m/z; HRMS calcd. for C 18 H 6 DB 9 : 406.056535; found: 406.056617. Stoichiometric reduction of diethyl benzylidenmalonate with [HDABCO][DB(2,4,6- O O -Ph) 3 ]: 12.4 µl (0.055 mmol) of diethyl benzylidenmalonate were added to a stirring solution of [HDABCO][DB(2,4,6--Ph) 3 ] (28.6 mg, EtO OEt 0.055 mmol) in CD 2 Cl 2. The resulting solution was heated to 50 C D and followed by GC-MS. After 1 hour the reaction was completed. Then, the solvent was removed and the residue purified by column chromatography (SiO2, hexanes : ethyl acetate, 10:1) affording the D-labelled product. 1 H NMR (400 MHz, CDCl 3 ) δ = 1.21 (t, J = 7.1 Hz, 3H9, 1.22 (t, J = 7.1 Hz, 3H), 3.20 (d, J = 7.8 Hz, 1H), 3.67 (d, J = 7.8 Hz, 1H), 4.12-4.20 (m, 4H), 7.19-7.22 (m, 3H), 7.26-7.30 (m, 2H) ppm. 13 C NMR (100 MHz, CDCl 3 ) δ = 14.1, 34.5 (t, J = 20.2 Hz), 53.9, 61.5, 126.8, 128.6, 128.9, 134.0 ppm. IR (neat) v ~ = 662, 699, 744, 786, 855, 909, 1033, 1095, 1148, 1175, 1207, 1256, 1368, 1451, 1496, 1605, 1729, 2983 cm -1. HRMS calcd. for C 14 H 17 DO 4 Na: 274.116002; found: 274.115865. 10
Selected NMR experiments 1 H NMR (300 MHz, CD 2 Cl 2 ) 6.71 6.69 6.68 6.66 5.32 B 6.00 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm 13 C NMR (75 MHz, CD 2 Cl 2 ) 169.04 168.82 168.60 168.41 168.21 168.02 165.66 165.44 165.22 165.07 164.87 164.67 101.21 101.16 100.87 100.83 100.80 100.76 100.47 100.43 53.84 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 11
19 NMR (75 MHz, CD 2 Cl 2 ) 6.00 2.97-96.36-96.40-100.90-100.93-100.97-60 -70-80 -90-100 -110-120 -130-140 ppm 11 B NMR (96 MHz, CD 2 Cl 2 ) 59.38 90 80 70 60 50 40 30 20 10 0-10 -20-30 -40 ppm 1 H NMR (300 MHz, CD 2 Cl 2 ) 12
7.21 7.19 7.18 7.16 7.14 7.13 7.05 7.03 7.02 7.02 7.00 7.00 6.99 6.97 5.32 B 3.01 3.00 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm 13 C NMR (75 MHz, CD 2 Cl 2 ) 164.33 164.20 164.17 161.01 160.98 160.88 156.04 155.84 155.66 152.61 152.43 152.24 149.18 149.14 149.02 148.98 145.92 145.88 145.76 145.72 125.73 125.70 125.61 125.47 125.38 125.35 106.73 106.46 106.31 106.04 53.84 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 19 NMR (75 MHz, CD 2 Cl 2 ) 13
3.00 2.87 2.90-100.40-100.43-100.46-100.49-125.99-126.02-126.06-126.10-143.88-143.94-143.96-144.01-60 -70-80 -90-100 -110-120 -130-140 ppm 11 B NMR (96 MHz, CD 2 Cl 2 ) 61.83 90 80 70 60 50 40 30 20 10 0-10 -20-30 -40 ppm 1 H NMR (300 MHz, CD 2 Cl 2 ) 14
3.00 5.81 7.56 7.54 7.53 7.52 7.51 7.50 7.49 7.48 7.46 6.93 6.91 6.88 5.32 B 9 8 7 6 5 4 3 2 1 ppm 13 C NMR (75 MHz, CD 2 Cl 2 ) 167.22 167.06 163.90 163.74 135.66 135.51 135.36 111.81 111.46 111.43 53.84 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 19 NMR (75 MHz, CD 2 Cl 2 ) 15
-99.83-60 -70-80 -90-100 -110-120 -130-140 ppm 11 B NMR (96 MHz, CD 2 Cl 2 ) 63.63 90 80 70 60 50 40 30 20 10 0-10 -20-30 -40 ppm 1 H NMR (400 MHz, CDCl3) 16
2.02 1.05 2.03 3.60 2.03 1.00 2.08 1.05 1.15 3.11 7.94 7.93 7.93 7.92 7.73 7.73 7.73 7.71 7.71 7.71 7.69 7.69 7.69 7.61 7.59 7.58 7.58 7.28 7.28 7.27 7.26 7.26 7.25 7.24 7.24 7.23 7.23 7.23 7.22 7.21 7.15 7.14 7.13 4.21 4.21 4.18 4.18 4.00 3.99 3.98 3.98 3.96 3.96 3.95 3.94 3.44 3.43 3.41 3.40 3.27 3.24 3.23 3.22 3.20 1.00 0.99 0.97 O O O S Ph OEt 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm 13 C NMR (101 MHz, CDCl3) 165.39 137.30 135.68 134.47 129.51 129.24 128.99 128.89 127.39 72.31 62.24 32.70 13.81 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 1 H NMR (400 MHz, CDCl3) 17
7.93 7.92 7.91 7.90 7.72 7.71 7.71 7.70 7.69 7.69 7.68 7.67 7.67 7.60 7.59 7.58 7.56 7.05 7.05 7.03 7.03 6.79 6.78 6.77 4.17 4.16 4.14 4.13 3.99 3.97 3.95 3.93 3.37 3.36 3.34 3.33 3.20 3.17 3.17 3.14 1.01 0.99 0.97 Ph O O S O OEt OMe 2.00 1.03 2.03 2.04 2.03 1.04 2.05 3.09 1.05 1.05 3.07 9 8 7 6 5 4 3 2 1 ppm 13 C NMR (101 MHz, CDCl3) 165.43 158.88 137.33 134.42 130.04 129.45 129.20 127.49 114.27 72.47 62.18 55.32 31.87 13.82 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 1 H NMR (300 MHz, CDCl3) 18
7.94 7.92 7.91 7.75 7.73 7.70 7.63 7.60 7.58 7.55 7.52 7.30 7.27 4.22 4.21 4.18 4.17 4.02 4.01 4.01 3.99 3.99 3.97 3.97 3.94 3.94 3.52 3.51 3.48 3.46 3.37 3.33 3.29 1.02 1.00 0.97 Ph O O S O OEt C 3 1.94 0.98 2.07 1.99 2.28 1.00 2.00 1.03 1.04 3.00 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm 13 C NMR (75 MHz, CDCl3) 165.13 139.99 137.26 134.64 129.49 129.47 129.35 125.94 125.90 125.85 125.80 71.88 62.49 32.36 13.80 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 1 H NMR (400 MHz, CDCl3) 19
4.02 2.02 4.07 3.00 2.00 1.01 2.04 7.88 7.86 7.68 7.66 7.65 7.54 7.52 7.50 7.19 7.18 7.17 7.04 7.03 7.02 4.75 4.74 4.73 3.54 3.53 O O O O Ph S S Ph 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm 13 C NMR (101 MHz, CDCl3) 138.27 136.30 134.65 129.59 129.24 128.79 128.76 127.31 85.39 31.42 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 ppm 1 H NMR (400 MHz, CDCl3) 20
3.96 2.01 4.01 2.00 1.97 1.00 3.01 2.01 7.87 7.87 7.85 7.85 7.68 7.66 7.64 7.54 7.52 7.50 6.95 6.93 6.72 6.71 6.70 4.71 4.69 4.68 3.76 3.49 3.47 O O O O S S Ph Ph MeO 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 ppm 13 C NMR (101 MHz, CDCl3) 158.83 138.37 134.61 129.92 129.60 129.23 128.26 114.19 85.62 55.38 30.65 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 1 H NMR (300 MHz, CDCl3) 21
3.92 2.02 4.02 2.05 2.01 1.03 2.00 7.88 7.87 7.85 7.85 7.84 7.71 7.70 7.70 7.69 7.68 7.67 7.66 7.66 7.65 7.56 7.55 7.55 7.53 7.51 7.50 7.46 7.44 7.20 7.17 4.73 4.71 4.69 3.61 3.59 O O O O S S Ph Ph 3 C 9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 ppm 13 C NMR (75 MHz, CDCl3) 140.46 138.11 134.86 129.62 129.37 129.33 125.84 125.79 125.74 125.69 85.03 31.32 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 ppm 22
1 H NMR (300 MHz, CDCl3) 2.32 3.00 4.07 0.97 1.00 6.11 7.30 7.26 7.22 7.19 4.20 4.12 3.65 3.63 3.21 3.19 1.23 1.22 1.21 1.20 1.19 1.19 O O EtO OEt D 9 8 7 6 5 4 3 2 1 ppm 13 C NMR (75 MHz, CDCl3) 168.92 137.97 128.91 128.56 126.79 61.49 53.88 34.67 34.47 34.27 14.08 190 180 170 160 150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 ppm 23
X-Ray Analysis: C19 C18 C20 C15 O3 O1 S1 O2 C9 C10 C11 C17 C16 S2 C1 C14 C13 C12 C4 O4 C2 C3 C5 C8 C6 Empirical formula C 20 H 18 O 4 S 2 Colour colourless ormula weight 386.46 g mol -1 Temperature 100 K Wavelength 0.71073 Å Crystal system MONOCLINIC Space group p 2 1 /c, (no. 14) Unit cell dimensions a = 8.0772 (5) Å α= 90. b = 20.4379(12) Å β= 95.577(5). c = 10.9593 (8) Å γ = 90. Volume 1800.6(2) Å 3 Z 4 Density (calculated) 1.426 Mg m -3 Absorption coefficient 0.319 mm -1 (000) 808 e Crystal size 0.47 x 0.11 x 0.08 mm 3 θ range for data collection 2.73 to 33.09. Index ranges -12 h 12, -31 k 31, -16 l 16 Reflections collected 37122 Independent reflections 6831 [R int = 0.0379] Reflections with I>2σ(I) 5533 Completeness to θ = 27.50 99.9 % Absorption correction Gaussian Max. and min. transmission 0.97556 and 0.90249 Refinement method ull-matrix least-squares on 2 Data / restraints / parameters 6831 / 0 / 235 Goodness-of-fit on 2 1.067 inal R indices [I>2σ(I)] R 1 = 0.0380 w R 2 = 0.0976 R indices (all data) R 1 = 0.0527 w R 2 = 0.1048 Largest diff. peak and hole 0.911 and -0.655 e Å -3 C7 Assessment of the relative Lewis acidity by Childs method: 24
O H 3 H 1 CH 3 H 2 Relative Proton δ (ppm) a Acidity (%) Lewis acid H 1 H 2 H 3 H 4 3-0,60 0,70 0,94 0,33 100 4-0,52 0,55 0,66 0,23 70 5-0,51 0,57 0,69 0,24 73 7-0,50 0,60 0,63 0,23 67 6-0,41 0,48 0,53 0,18 56 a Chemical shifts were determined in CD 2 Cl 2, (0.1 M). 25