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2-Benzyl-5-ethylidene-6-oxo-4-vinyl-1,2,5,6-tetrahydropyridine-2-carboxylic acid isobutyl-
amide (154b). Prepared by following general procedure I, using 146a (0.240 g, 0.808 mmol),
HOBt (0.109 g, 0.808 mmol), EDCI (0.155 g, 0.808 mmol), DMAP (0.098 g, 0.81 mmol) and i-
butylamine (0.081 mL, 0.81 mmol). Isolated yield 154b (0.178 g, 60%).
1 H NMR (300 MHz, CDCl3): δ 7.28-7.15 (m, 5H), 6.55 (bs, 1H), 6.43-6.35 (m, 1H), 6.31 (ddd, J
= 17.2, 10.8, 0.9 Hz, 1H), 6.24 (q, J = 7.5 Hz, 1H), 5.98 (s, 1H), 5.47 (dd, J = 17.2, 1.6 Hz, 1H),
5.23 (dd, J = 10.8, 1.6 Hz, 1H), 3.53 (d, J = 13.2 Hz, 1H), 3.04-2.96 (m, 3H), 2.18 (d, J = 7.5 Hz,
3H), 1.70 (sep, J = 6.7 Hz, 1H), 0.79 (d, J = 6.7 Hz, 3H), 0.78 (d, J = 6.7 Hz, 3H); 13 C NMR (75
MHz, CDCl3): δ 170.8, 165.7, 139.0, 136.6, 134.3, 133.6, 130.5, 128.4, 127.2, 125.2, 122.1,
118.2, 65.8, 47.2, 45.3, 28.2, 19.9, 16.1; IR (thin film): ν 3337, 2959, 1671, 1636 cm -1 ; MS m/z
(%) 338 (9), 247 (11), 238 (100), 91 (65).
General procedure J for preparation of imino-oxazolidinones 155a and 15b.
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8a-Benzyl-6-ethylidene-1-ethylimino-7-vinyl-6,8a-dihydro-1H-oxazolo[3,4-a]pyridine-3,5-
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dione (155a). A solution of diamide 154a (0.710 g, 2.01 mmol) in CH2Cl2 (150 mL) was cooled
to -10 ºC, and Et3N (0.839 mL, 6.03 mmol) was added. Then, phosgene (1.42 mL, 3.02 mmol of
a 20 % solution in toluene) was added dropwise, and the reaction was stirred for 10 min at -10
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