tert-butyl (6R,7R)-3-[(acetyloxy)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate → t-Butyl 3-acetoxymethyl-7beta-(2-dichloroacetoxyimino-2-phenylacetamido)-ceph-3-em-4-carboxylate

Participants

Reaction Steps

To a solution of t-butyl 3-acetoxymethyl-7β-aminoceph-3-em-4-carboxylate (3.28 g) in ethyl acetate (25 ml.) was added a solution of 2-dichloroacetoxyimino-2-phenylacetyl chloride (syn-isomer) in ethyl acetate (25 ml.) dropwise with stirring. The solution became warm and a precipitate formed. After two hours, the solution was filtered, washed successively with 2 N-hydrochloric acid, water, and saturated sodium bicarbonate solution, dried, and evaporated to give a yellow foam which solidified on standing, and was triturated with petroleum spirit giving t-butyl 3-acetoxymethyl-7β-(2-dichloroacetoxyimino-2-phenylacetamido)-ceph-3-em-4-carboxylate (4.0 g; 70%), νmax. (CHBr3) 3420 (NH), 1796 (β-lactam), 1730 and 1230 (acetate), 1700 and 1512 cm-1 (CONH), τ (DMSO-d6) values include 2.1-2.5 (multiplet; aromatic protons), 2.98 (singlet; CHCl2), 7.6 (singlet; CH3CO), 8.5 (singlet; t-butyl ester).

Provenance & Evidence