Synthetic Studies of Carbapenem and Penem Antibiotics. II. Synthesis of 3-Acetyl-2-azetidinones by (2+2) Cycloaddition of Diketene and Schiff Bases

Abstract

It was found that (2+2) cycloaddition reaction of diketene with Schiff bases was effectively promoted by imidazole as a catalyst to afford 3-acetyl-2-azetidinone derivatives 4. As an application of this new method, a practical asymmetric synthesis of 4 and its conversion into (3S, 4S)-4-carboxy-1-(di-p-anisylmethyl)-3-[(R)-1-hydroxyethyl]-2-azetidinone, which is a key intermediate for the synthesis of carbapenem and penem antibiotics, were accomplished.