反应详情

A solution of trimethylsilyl 2,2-dimethyl-6β-trimethylsilylaminopenam-3α-carboxylate [prepared from the corresponding amino-acid (0.864 g.)] and propylene oxide (1 ml.) in dichloromethane (20 ml.) was cooled to 0° and treated dropwise with a solution of 2-dichloroacetoxyimino(thien-2-yl)acetyl chloride syn-isomer; [prepared from the corresponding acid (0.753 g.)] in dichloromethane (12 ml.). The resulting solution was maintained at 0° for 1 hour and was then evaporated to a small bulk and partitioned between ethyl acetate and saturated sodium bicarbonate solution. The aqueous phase was washed with ethyl acetate, acidified with 2N-hydrochloric acid, and extracted with ethyl acetate. The dried organic solution was evaporated to a small bulk and added dropwise to stirred petroleum spirot (b.p. 40°-60° ). The resulting precipitate was collected, washed, and dried to afford the title acid (0.337 g., 24% based on amine), [α D + 224° (c 0.57, DMSO), λmax. (pH 6 buffer) 288 nm (ε 6,400), λ inf. 270 nm (ε 5,800), νmax. (Nujol), 2600 and 1730 (COH), H), 1776 (β-lactam), 1670 and 1526 cm.-1 (CONH), τ (d6 -DMSO) values include 0.44 (d, J 6 Hz; NH), 2.45 and 2.9 (multiplets, aromatic protons), 5.78 (s; C-3H), 8.46 and 8.55 (2 s; CH3 groups).

1. temperaturewas cooled to 0°
2. temperatureThe resulting solution was maintained at 0° for 1 hour
3. customwas then evaporated to a small bulk
4. custompartitioned between ethyl acetate and saturated sodium bicarbonate solution
5. washThe aqueous phase was washed with ethyl acetate
6. extractionextracted with ethyl acetate
7. customThe dried organic solution was evaporated to a small bulk
8. additionadded dropwise
9. customThe resulting precipitate was collected
10. washwashed
11. customdried
12. customto afford the title acid (0.337 g., 24% based on amine)
13. custom0.44 (d, J 6 Hz; NH), 2.45 and 2.9 (multiplets, aromatic protons), 5.78 (s; C-3H), 8.46 and 8.55 (2 s; CH3 groups)