Methyl 3-methyl-2-(2-chlorosulfinyl-4-oxo-3-phthalimido-1-azetidinyl)-3-butenoate → Methyl 7-phthalimido-3-methylenecepham-4-carboxylate 1-oxide

Participants

Reaction Steps

Methyl 3-methyl-2-(2-chlorosulfinyl-4-oxo-3-phthalimido-1-azetidinyl)-3-butenoate (0.20 g.) was stirred in about 27 g. of polyphosphoric acid for 20 minutes. Ice water and ethyl acetate (25 ml.) was added to the reaction mixture. The organic layer was separated and washed successively with water, aqueous sodium bicarbonate, and brine, dried (MgSO4), and evaporated in vacuo to dryness to give methyl 7-phthalimido-3-methylenecepham-4-carboxylate 1-oxide (0.05 g.) as a white foam.

Provenance & Evidence