Compound 17
(3R,4S)-3-((1,3-diphenyl-1H-pyrazol-4-yl)methyl)-1-tosylpiperidine-4-carbaldehyde
From: Direct, enantioselective α-alkylation of aldehydes using simple olefins
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Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
Prepared according to the general procedure outlined for compound 13 using (E)-N-(3-(1,4-diphenyl-1H-pyrrol-3-yl)allyl)- 4-methyl-N-(4-oxobutyl)benzenesulfonamide. Purified by flash chromatography (20-30% EtOAc/hexanes) to provide the title compound (68 mg, 77% yield, 3:1 dr, 90% ee) as a pale yellow oil. Analytical data: [α]D21-25.5 (c = 1.00, CHCl3); 1H NMR (500 MHz, CDCl3): δ 9.43 (d, J = 1.6 Hz, 1H), 7.98, (s, 1H), 7.78 (d, J = 7.7 Hz, 2H), 7.67 (d, J = 7.1 Hz, 2H), 7.49-7.45 (m, 6H), 7.41 (d, J = 7.4 Hz, 1H), 7.30-7.24 (m, 3H), 3.08-3.03 (m, 1H), 3.00 (d, J = 11.2 Hz, 1H), 2.89-2.83 (m, 2H), 2.64-2.60 (m, 1H), 2.40 (s, 3H), 2.31-2.35 (m, 2H), 2.17 (q, J = 5.6 Hz, 1H), 1.92-1.82 (m, 2H); 13C NMR (125 MHz, CDCl3): δ 202.5, 151.8, 143.7, 139.8, 133.4, 132.6, 129.7, 129.4, 128.7, 128.0, 127.5, 126.3, 118.8, 117.2, 50.7, 47.9, 44.6, 35.1, 26.0, 22.8, 21.5; HRMS (ESI+) Calcd. for C29H30N3O3S+H, 500.2002; Found, 500.2012; IR (thin film, cm-1) 3059, 2927, 2852, 3721, 2255, 1722, 1598, 1551, 1503, 1449, 1334, 1265, 1161, 1090, 1064, 957, 909, 815, 757; TLC (70:30 hexanes:EtOAc): Rf= 0.21. HPLC analysis of the corresponding alcohol (AS, 30% iPrOH/hexane, 1.0 mL/min, 220 nm) indicates 90% ee: tR= 12.4, 15.8 min.
