Practical Synthesis of Penems and Carbapenems Key Intermediate
31 December 2000 (online)
Titanium enolate-mediated aldol reaction of chiral N-phthaloyl-β-alanyl-1,3-benzoxazinone 5 with acetaldehyde furnished the (2S, 3R)-syn-aldol 6 in high yield with high stereoselectivity. Silylation of the hydroxy group of 6 followed by removal of the protective groups and cyclization gave the optically pure β-lactam 9 which was transformed into the acetoxyazetidinone 3, a key intermediate of penems and carbapenems.
acetoxyazetidinone - carbapenem - asymmetric aldol reaction