Syntheses of 2-Azetidinone (β-Lactam) Ring by Chlorosulfonyl Isocyanate (CSI)

Abstract

Attempts were made to prepare sulfur substituted 2-azetidinones by the reaction of vinylsulfide with chlorosulfonyl isocyanate (CSI). The main product of the reaction of β-methylthiostyrene (I) with CSI was pyridone derivative (II), but in the case of 1-phenylthio-1-propene (V) the main products were dihydrouracil derivatives (VI and VII) and acrylic acid derivatives (VIII and IX). Reaction of 1-p-chloro- or p-methylphenylthio-1-propene (Xa and b) with CSI in dry ether at -30°gave the desired 2-azetidinone (β-lactam) derivatives (XIa and b) in 63 and 66.4% isolated yield respectively.