An efficient synthesis of 6-oxopenicillanic and 7-oxocephalosporanic acid derivatives

Abstract

Trifluoromethanesulphonation of benzyl 6-aminopenicillanate (3) and the 7-aminocephalosporanates (7a–c) with (CF₃SO₂)₂O gave the bis(trifluoromethylsulphonate) derivatives (5) and (8a–c), which were then converted into the imines (6) and (9a–c) by treatment with 1,5-diazabicyclo[5.4.0] undec-5-ene or triethylamine, and subsequently hydrolysed with dilute HCl to give the 6-oxopenicillanic acids (1) and 7-oxocephalosporanic acids (2), respectively.