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Synlett 2006(9): 1443-1445  
DOI: 10.1055/s-2006-939710
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Convenient Approach to (-)-8-epi-Swainsonine

Adrian J. Murray, Philip J. Parsons*
Department of Chemistry, School of LifeSciences, University of Sussex, Falmer, Brighton, East Sussex, BN1 9QJ, UK
Fax: +44(1273)677196; e-Mail: P.J.Parsons@sussex.ac.uk;
Further Information

Publication History

Received 13 February 2006
Publication Date:
26 April 2006 (online)

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Abstract

A novel and efficient synthesis of (-)-8-epi-swainsonine (2) is reported. Face-selective diol formation from the bicyclic ­alkene 3 followed by a stereoselective vinylation of the aldehyde and ring-closing metathesis gave the indolizidine ring system, which was converted into (-)-8-epi-swainsonine (2).

Key words

stereoselective - indolizidine synthesis - metathesis - ­stereoelectronic

17

Data for Compound 12.
Colourless oil; R f = 0.66 (30% Et2O-PE); [α]D 28 -50.5 (c 2.2, CHCl3). IR (film): 3080, 2956, 2931, 2858, 2792, 1644, 1473, 1463, 1420, 1403, 1379, 1369, 1277, 1255, 1210, 1169, 1139, 1112, 1092, 1019, 1005, 926, 873, 838, 777, 676 cm-1. 1H NMR (300 MHz, CDCl3): δ = 0.03 and 0.08 [6 H, 2 × s, SiC(CH3)2], 0.90 [9 H, s, SiC(CH3)3], 1.28 and 1.53 [6 H, 2 × s, C(CH3)2], 2.02 (1<H, dd, J = 3.7, 11.5 Hz, 5-H), 2.11 (1 H, dd, J = 3.4, 7.8 Hz, 2-H), 2.63 (1 H, dd, J = 7.7, 14.0 Hz, 6-H), 3.22 (1 H, d, J = 11.5 Hz, 5-H), 4.03 (1 H, m, 6-H), 4.49-4.56 (3 H, m, 3-H, 4-H, 9-H), 5.03-5.18 (3 H, m, 8-H, 11-H), 5.30 (1 H, d, J = 17.2 Hz, 11-H), 5.87 (1 H, m, 7-H), 6.15 (1 H, ddd, J = 5.9, 10.8, 17.2 Hz, 10-H). 13C NMR (75 MHz, CDCl3): δ = -4.7 and -4.0 [Si(CH3)2], 18.2 [SiC(CH3)3], 25.5 [C(CH3)2], 26.0 [SiC(CH3)3], 26.3 [C(CH3)2], 58.1 (C-6), 60.5 (C-5), 71.6 (C-2), 74.4, 77.3 and 81.5 (C-3, C-4, C-9), 110.8 [C(CH3)2], 115.1 (C-11), 116.2 (C-8), 135.9 (C-7), 139.6 (C-10). HRMS (ESI): m/z calcd for C19H36NO3Si [M + H]+: 354.2459; found: 354.2448.

20

Data for Compound 13.
Colourless oil; R f = 0.40 (75% Et2O-PE); [α]D 28 19.6 (c 1.5 in CHCl3). IR (film): 3037, 2952, 2928, 2856 2781, 1719, 1660, 1461, 1379, 1253, 1207, 1167, 1150, 1119, 1045, 1011, 961, 938, 901, 860, 836, 775, 653 cm-1. 1H NMR (300 MHz, CDCl3): δ = 0.11 and 0.13 [6 H, s, Si(CH3)2], 0.91 [9 H, s, SiC(CH3)3], 1.29 and 1.51 [6 H, s, C(CH3)2], 2.10-2.11 (1 H, m, 6-H), 2.14 (1 H, dd, J = 5.7, 11.4 Hz, 2-H), 2.59 (1 H, d, J = 17.1 Hz, 9-H), 3.33 (1 H, d, J = 11.4, 2-H), 3.60-3.67 (1 H, m, 9-H), 4.50 (1 H, m, 5-H), 4.62 (1 H, dd, app. t, J = 6.0 Hz, 7-H), 4.69 (1 H, dd, J = 3.8, 6.0 Hz, 8-H), 5.77-5.79 (2 H, m, 3-H, 4-H). 13C NMR (75 MHz, CDCl3): δ = -5.3 and -4.4 [Si(CH3)2], 18.8 [SiC(CH3)3], 24.2 [C(CH3)2], 26.1 [SiC(CH3)3], 26.5 [C(CH3)2], 53.3 (C-9), 61.9 (C-2), 65.3 (C-5), 67.2 (C-6), 77.8 (C-7), 80.8 (C-8), 111.2 [C(CH3)2], 126.8 and 127.5 (C-3 and C-4). HRMS (ESI): m/z calcd for C17H32NO3Si [M + H]+: 326.2146; found: 326.2138.