Dimethyl Sulfoxide → HCID 86733037, compound

Participants

Reaction Steps

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 resuling 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 2 N-hydrochloric acid, and extracted with ethyl acetate. The dried organic solution was evaporated to a small bulk and added dropwise to stirred petroleum spirit (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 (CO2H), 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).

Provenance & Evidence