Reaction Steps
To a solution of (4R)-4-benzyl-3-[(2R)-2-methylbut-3-enoyl]-1,3-oxazolidin-2-one (0.65 mmol, 170 mg) and allyltrimethyl silane (1.9 mmol, 0.31 mL) in DCM (2 mL) at reflux was added 5 mol % of Grubbs' second generation catalyst (28 mg). After 72 hrs the solvent was removed in vacuo. The crude product was purified by column chromatography to a colourless oil. (83 mg, 77%) E/Z 3:1. NMR data of the mixture of E/Z isomers. 1H NMR (400 MHz, CDCl3): δ=7.21-7.36 (m, 5H), 5.64 (dt, J=8.1, 15.4, 1H), 5.41-5.58, (m, 2 HZ) 5.32-5.39 (m, 1H), 4.68-4.78 (m, 1 HZ) 4.59-4.68 (m, 1H), 4.38-4.48 (m, 1H), 4.14-4.19 (m, 2H), 3.30 (dd, J=3.28, 13.14, 1H), 2.78 (dd, J=9.6, 13.14, 1H), 1.48-1.63 (m, 2 HZ), 1.46 (d, J=8.1, 2H), 1.31 (d, J=6.8, 3 HZ), 1.30 (d, J=6.8, 3H), 0.0 (s, 9 HZ), −0.02 (s, 9H); 13C NMR (100 MHz, CDCl3): δ=175.5, 152.3, 135.4Z or E, 135.3Z or E, 129.7Z or E, 129.5Z or E, 128.9Z or E, 128.1Z, 127.3, 126.9, 126.1Z, 66.03, 66.0Z, 55.6, 55.5Z, 40.9, 37.9, 37.8Z, 35.8Z, 22.9, 19.0Z, 17.9, −1.8Z, −1.9; IR (CHCl3): v 2955, 1783, 1699, 1454, 1381, 853; HMRS required for C19H27NO3Si ([M+H]+) 346.1838 found 346.1847; [α]D23=−131.6 (c, 2, CHCl3).
