Supporting Information

Supporting Information Copyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, 2013 Paraldehyde as an Acetaldehyde Precursor in Asymmetric Michael Reactions Promoted by Site-Isolated Incompatible Catalysts Xinyuan Fan, [a] Carles Rodríguez-Escrich, [a] Sonia Sayalero, [a] [a, b] and Miquel A. Pericàs* chem_201302087_sm_miscellaneous_information.pdf

Supporting Information Paraldehyde as an Acetaldehyde Precursor in Asymmetric Michael Reactions Promoted by Site-isolated Incompatible Catalysts ** Xinyuan Fan, Carles Rodríguez-Escrich, Sonia Sayalero, Miquel A. Pericàs* Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans, 16, 43007 Tarragona (Spain) and Departament de Química rgànica, Universitat de Barcelona (UB), 08028 Barcelona (Spain) mapericas@iciq.es Table of Contents 1. General information S2 2. Study of the acid-catalyzed paraldehyde decomposition S2 3. Confinement of catalyst 2 in a tea-bag S3 4. General procedure for Michael reaction S3 4.1. General procedure for the obtention of aldehyde products (without reduction) S3 4.2. General procedure for the obtention of alcohol products (with reduction) S3 5. Characterization data for alcohols 4 S4 6. Pictures of reaction set-up, HPLC chromatograms, 1 H and 13 C NMR spectra S6 7. References S27 S1

1. General information Unless otherwise stated, all commercial reagents were used as received. Flash chromatography was carried out using 60 mesh silica gel and dry-packed columns. Thin layer chromatography was carried out using Merck TLC Silicagel 60 F254 aluminum sheets. Components were visualized by UV light (λ = 254 nm) and stained with p-anisaldehyde or phosphomolybdic dip. NMR spectra were registered in a Bruker Advance 400 Ultrashield spectrometer in CDCl 3 at room temperature, operating at 400 or 500 MHz ( 1 H) and 100 or 126 MHz ( 13 C{ 1 H}). TMS was used as internal standard for 1 H NMR and CDCl 3 for 13 C NMR. Chemical shifts are reported in ppm referred to TMS. IR spectra were recorded on a Bruker Tensor 27 FT-IR spectrometer. Elemental analyses of the polystyrene supported catalysts were performed on a LEC CHNS 932 micro-analyzer at the Universidad Complutense de Madrid, Spain. High performance liquid chromatography (HPLC) was performed on an Agilent Technologies chromatograph (1100 Series), using Chiralcel columns and guard columns. Racemic standard products were prepared according to reported procedures catalyzed by racemic catalyst in order to establish HPLC conditions. The absolute configuration of the reaction products was confirmed by HPLC, by comparison with reported data. Catalyst 1 was prepared according to the previous reported procedure. [1] Catalyst 2 was purchased from Novabiochem. The tea-bag was made of a real tea-bag, which was purchased from Müller. 2. Study of the acid-catalyzed paraldehyde decomposition 10 mol% acidic catalyst RT, 90 min., CDCl 3 3 Entry Acidic catalyst bservation 1 AcH No acetaldehyde, only paraldehyde. 2 PhCH No acetaldehyde, only paraldehyde. 3 p-c 6H 4CH No acetaldehyde, only paraldehyde. 4 p-mec 6H 4S 3H acetaldehyde / paraldehyde, 70 : 30. In order to find a suitable co-catalyst for the generation of acetaldehyde from paraldehyde, four acids were tested. To a NMR tube, 10 mol% of acidic catalyst was mixed with paraldehyde in CDCl 3. The mixture was detected directly by NMR after shaking for 90 minutes at room temperature. Commonly used acidic additives such as acetic acid, benzoic acid and p-nitrobenzoic acid, were not able to decompose paraldehyde as none of these three reaction mixtures showed acetaldehyde signal in the 1 H NMR spectra. Nevertheless, the S2

strongest acidic catalyst, p-toluenesulfonic acid (PTSA) catalyzed the decomposition reaction and a 30 : 70 ratio of paraldehyde to acetaldehyde was detected. 3. Confinement of catalyst 2 in a tea-bag Catalyst 2 (f = 3.0 mmol g-1, 6.7 mg, 0.02 mmol) was enclosed in a tea-bag, which was then closed with fine cotton thread. This tea-bag was washed with CH2Cl2 twice before using. Figure 1. Homemade tea-bag on a coin (1 euro). 4. General procedure for Michael reaction 4.1 General procedure for the obtention of aldehyde products (without reduction) 1 (20 mol%), 2 (10 mol%) CH2Cl2, RT + N2 N2 Catalyst 1 (20 mol%, 0.04 mmol), co-catalyst 2 (10 mol%, 0.02 mmol) in a homemade teabag and trans-β-nitrostyrene (0.2 mmol) were mixed in a vial with degassed anhydrous CH2Cl2 (1 ml) in a glove box. Then paraldehyde (0.66 mmol) was added and the vial was sealed and shaken at room temperature. After 24 h, the mixture was filtered and washed with CH2Cl2 (3 1 ml). The filtrates were combined and the solvent was removed under reduced pressure. Product was purified by flash chromatography on silica gel, with hexanes/ethyl acetate mixtures as eluent. 4.2 General procedure for the obtention of alcohol products (with reduction) 1) 1 (20 mol%), 2 (10 mol%) CH2Cl2, RT + R N2 2) EtH, NaBH4, 0 oc, 20 min R N2 Catalyst 1 (20 mol%, 0.04 mmol), catalyst 2 (10 mol%, 0.02 mmol) in a homemade tea-bag and the corresponding nitroalkene compound (0.2 mmol) were mixed in a vial with degassed S3

anhydrous CH 2 Cl 2 (1 ml) in a glove box. Then, paraldehyde (0.66 mmol) was added and the vial was sealed and shaken at room temperature. After 24 h, the mixture was filtered and washed with CH 2 Cl 2 (3 1 ml). The filtrates were combined and the solvent was removed under reduced pressure. The crude aldehyde product was dissolved in 0.5 ml EtH. After that, this solution was slowly added into a NaBH 4 (0.6 mmol) solution in 0.2 ml EtH under stirring at 0 º C (note: longer reaction time under room temperature could cause low reduction yield). After 20 min, the reaction mixture was treated with saturated aqueous NH 4 Cl solution (5 ml) and extracted with CH 2 Cl 2 (3 3 ml). The organic fraction was dried over MgS 4 and concentrated under reduced pressure at room temperature. Products were purified by flash chromatography on silica gel, with hexanes/ethyl acetate mixtures as eluent. 5. Characterization data for Michael products 4a. [2] 1 H NMR (500 MHz, CDCl 3 ): δ = 2.95 (d, J = 7.1 Hz, 2H), 4.03-4.16 (m, 1H), 4.58-4.72 (m, 2H), 7.20-7.40 (m, 5H), 9.71 (t, J = 1.9 Hz, 1H); HPLC (Chiralcel AS-H, Hexane/i-Propanol (70:30), flow rate = 1.0 ml min -1, λ = 210 nm): t major = 14.5 min, t minor = 19.2 min. F N 2 4b. 1 H NMR (500 MHz, CDCl 3 ): δ = 1.42 (s, 1H), 1.96-2.04 (m, 2H), 3.48-3.55 (m, 1H), 3.62-3.69 (m, 1H), 3.90-3.99 (m, 1H), 4.77-4.68 (m, 2H), 7.03-7.15 (m, 2H) 7.19-7.31 (m, 2H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 161.2 (d, J = 246.2 Hz), 129.9 (d, J = 4.7 Hz), 129.6 (d, J = 8.6 Hz), 125.8 (d, J = 13.6 Hz), 124.8 (d, J = 3.5 Hz), 116.3 (d, J = 22.3 Hz), 79.1 (d, J = 2.9 Hz), 60.1, 36.5, 34.6 (d, J = 1.9 Hz); IR (ATR): ν = 758, 1044, 1224, 1378, 1491, 1547, 2885, 2925, 3359 cm -1 ; HRMS calcd for C 10 H 11 F (M - H 2 + H) + : 196.0768, found: 196.0762; HPLC (Chiralcel D-H, Hexane/i-Propanol (96:4), flow rate = 0.8 ml min -1, λ = 210 nm): t major = 61.5 min, t minor = 25 55.6 min. [α] D = - 89.5 (c = 0.055 in CHCl 3 ). Cl N 2 4c. 1 H NMR (500 MHz, CDCl 3 ): δ = 1.44 (s, 1H), 2.00-2.07 (m, 2H), 3.52-3.60 (m, 1H), 3.61-3.68 (m, 1H), 4.24-4.32 (m, 1H), 4.67-4.77 (m, 2H), 7.20-7.30 (m, 3H) 7.41 (dd, J = 7.8, 1.1 Hz, 1H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 136.5, 134.4, 130.5, 129.0, 128.3, 127.6, 79.1, 60.1, 37.6, 34.9; IR (ATR): ν = 756, 1037, 1378, 1434, 1476, 1547, 2885, 2923, 3359 cm -1 ; HRMS calcd for C 10 H 11 Cl (M - H 2 + H) + : 212.0473, found: 212.0483; HPLC (Chiralpak IC, Hexane/i-Propanol (90:10), flow rate = 1.0 ml min -1 25, λ = 210 nm): t major = 19.6 min, t minor = 17.0 min. [α] D = 48.82 (c = 0.17 in CHCl 3 ). S4

Br N 2 4d. [3] 1 H NMR (500 MHz, CDCl 3 ): δ = 1.47 (t, J = 5.0 Hz, 1H), 1.96-2.08 (m, 2H), 3.52-3.67 (m, 2H), 4.24-4.34 (m, 1H), 4.68-4.73(m, 2H), 7.13-7.17 (m, 1H), 7.24 (dd, J = 7.8, 1.7 Hz, 1H), 7.33 (td, J = 7.5, 1.2 Hz, 1H), 7.60 (dd, J = 8.0, 1.2 Hz, 1H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 138.2, 133.8, 129.3, 128.2, 128.1, 125.1, 79.3, 60.0, 39.8, 35.2; HPLC (Chiralpak IC, Hexane/i-Propanol (90:10), flow rate = 1.0 ml min -1, λ = 210 nm): t major = 20.9 min, t minor = 17.7 min. Cl N 2 4e. 1 H NMR (500 MHz, CDCl 3 ): δ = 1.86-1.92 (m, 1H), 1.95-2.02 (m, 1H), 3.47-3.52 (m, 1H), 3.63-3.67 (m, 1H), 3.69-3.75 (m, 1H), 4.60 (dd, J = 12.6, 8.6 Hz, 1H), 4.67 (dd, J = 12.6, 6.8 Hz, 1H), 7.11-7.13 (m, 1H), 7.22 (d, J = 1.9 Hz, 1H), 7.26-7.30 (m, 2H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 141.0, 134.9, 130.3, 128.1, 127.8, 125.9, 80.2, 59.6, 40.7, 35.5; IR (ATR): ν = 756, 1037, 1378, 1434, 1476, 1547, 2885, 2923, 3359 cm -1 ; HRMS calcd for C 10 H 11 Cl (M - H 2 + H) + : 212.0473, found: 212.0477; HPLC (Chiralpak D-H, Hexane/i-Propanol (90:10), flow rate = 1.0 ml min -1, λ 25 = 210 nm): t major = 22.5 min, t minor = 20.3 min. [α] D = - 4.1 (c = 0.105 in CHCl 3 ). Cl N 2 4f. [3] 1 H NMR (500 MHz, CDCl 3 ): δ = 1.25 (s, 1H), 1.83-1.91 (m, 1H), 1.95-2.01 (m, 1H), 3.47-3.51 (m, 1H), 3.62-3.66 (m, 1H), 3.69-3.75 (m, 1H), 4.58 (dd, J = 12.4, 8.7 Hz, 1H), 4.66 (dd, J = 12.5, 6.7 Hz, 1H), 7.17 (d, J = 8.4 Hz, 2H), 7.32 (d, J = 8.4 Hz, 2H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 137.5, 133.8, 129.4, 129.1, 80.5, 59.8, 40.6, 35.7; HPLC (Chiralpak IC, Hexane/i-Propanol (90:10), flow rate = 1.0 ml min -1, λ = 210 nm): t major = 19.3 min, t minor = 17.0 min. 4g. [3] 1 H NMR (500 MHz, CDCl 3 ): δ = 1.85-1.99 (m, 2H), 3.47-3.52 (m, 1H), 3.60-3.68 (m, 2H), 3.79 (s, 3H, CH 3 ), 4.56 (dd, J = 12.2, 8.3 Hz, 1H), 4.62 (dd, J = 12.2, 7.2 Hz, 1H), 6.87 (d, J = 8.6 Hz, 2H), 7.14 (d, J = 8.6 Hz, 2H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 159.2, 130.8, 128.7, 114.6, 81.1, 60.1, 55.4, 40.6, 35.8; HPLC (Chiralpak IC, Hexane/i-Propanol (90:10), flow rate = 1.0 ml min -1, λ = 210 nm): t major = 34.8 min, t minor = 30.1 min. 4h. [3] 1 H NMR (500 MHz, CDCl 3 ): δ = 1.31 (s, 1H), 1.81-1.99 (m, 2H), 3.47-3.55 (m, 1H), 3.60-3.68 (m, 2H), 4.54 (dd, J = 12.2, 8.5 Hz, 1H), 4.61 (dd, J = 12.2, 7.0 Hz, 1H), 5.95 (s, 2H), 6.67-6.71 (m, 2H), 6.76 (d, J = 7.8 Hz, 1H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 148.3, 147.3, 132.6, 121.1, 108.8, S5

107.7, 101.4, 81.0, 60.0, 41.1, 35.8; HPLC (Chiralpak D-H, Hexane/i-Propanol (90:10), flow rate = 1.0 ml min -1, λ = 210 nm): tmajor = 39.5 min, tminor = 34.4 min. N 2 4i. [3] 1 H NMR (500 MHz, CDCl 3 ): δ = 1.54 (s, 1H), 1.90-2.04 (m, 2H), 3.56-3.61 (m, 1H), 3.68-3.73 (m, 1H), 3.84-3.89 (m, 1H), 4.63 (dd, J = 12.5, 6.7 Hz, 1H), 4.68 (dd, J = 12.5, 8.0 Hz, 1H), 6.19 (d, J = 3.2 Hz, 1H), 6.31 (dd, J = 3.2, 1.9 Hz, 1H), 7.36 (dd, J = 1.9, 0.8 Hz, 1H); 13 C{H} NMR (126 MHz, CDCl 3 ): δ = 152.1, 142.5, 110.5, 107.7, 78.4, 60.0, 35.0, 33.8; HPLC (Chiralpak IC, Hexane/i-Propanol (90:10), flow rate = 1.0 ml min -1, λ = 210 nm): t major = 19.4 min, t minor = 16.8 min. H 4j. [3] 1 H NMR (400 MHz, CDCl 3 ): δ = 1.40 (br s, 1H), 1.62-1.82 (m, 4H), 2.43 (hept, J = 6.5 Hz, 1H), 2.69 (t, J = 8.4 Hz, 2H), 3.70-3.81 (m, 2H), 4.44 (dd, J = 12.0, 6.5 Hz, 1H), 4.51 (dd, J = 12.0, 6.3 Hz, 1H), 7.15-7.23 (m, 3H), 7.27-7.32 (m, 2H); 13 C{H} NMR (100 MHz, CDCl 3 ): δ = 141.1, 128.5, 128.3, 126.2, 79.2, 60.1, 34.4, 33.9, 33.3, 32.7; HPLC (Chiralpak IC, Hexane/CH 2 Cl 2 /i-propanol (54:45:1), flow rate = 1.0 ml min -1, λ = 230 nm): tmajor = 14.2 min, tminor = 16.3 min. 6. Pictures of reaction set-up, HPLC chromatograms, 1 H and 13 C NMR spectra Figure 2. Reaction under moisture (left, catalyst 1 is dark red after reaction) and reaction in degassed anhydrous CH 2 Cl 2 in a glovebox (right, catalyst 1 is yellow after reaction). S6

Chiralcel AS-H, Hexane/i-Propanol 70:30, flow rate 1.0 ml min -1, λ = 210 nm S7

Chiralcel D-H, Hexane/i-Propanol 96:4, flow rate 0.8 ml min -1, λ = 210 nm F S8

Chiralpak IC, i-propanol/hexane = 10/90, 25 o C, flow rate = 1.0 ml/min, λ = 210 nm Cl S9

Chiralpak IC, i-propanol/hexane = 10/90, 25 o C, flow rate = 1.0 ml/min, λ = 210 nm Br S10

Chiralpak D-H, i-propanol/hexane = 10/90, 25 o C, flow rate = 1.0 ml/min, λ = 210 nm Cl S11

Chiralpak IC, i-propanol/hexane = 10/90, 25 o C, flow rate = 1.0 ml/min, λ = 210 nm Cl S12

Chiralpak IC, i-propanol/hexane = 10/90, 25 o C, flow rate = 1.0 ml/min, λ = 210 nm S13

Chiralpak D-H, i-propanol/hexane = 10/90, 25 o C, flow rate = 1.0 ml/min, λ = 210 nm S14

Chiralpak IC, i-propanol/hexane = 10/90, 25 o C, flow rate = 1.0 ml/min, λ = 210 nm S15

Chiralpak IC, Hexane/CH 2 Cl 2 /i-propanol (54:45:1), flow rate = 1.0 ml min -1, λ = 230 nm H S16

F S17

Cl S18

Br S19

Cl S20

Cl S21

S22

S23

S24

H S25

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7. References [1] a) X. Fan, S. Sayalero, M. A. Pericàs, Adv. Synth. Catal. 2012, 354, 2971-2976; b) E. Alza, M. A. Pericàs, Adv. Synth. Catal. 2009, 351, 3051-3056. [2] a) P. García-García, A. Ladépêche, R. Halder, B. List, Angew. Chem. Int. Ed. 2008, 47, 4719-4721; b) Y. Hayashi, T. Itoh, M. hkubo, H. Ishikawa, Angew. Chem. Int. Ed. 2008, 47, 4722-4724. [3] Y. Qiao, J. He, B. Ni, A. D. Headley, Adv. Synth. Catal. 2012, 354, 2849-2853. S27