Pummerer-type cyclization of Arnstein tripeptide analogues induced by O-silylated ketene acetals: Studies of penicillin biosynthesis
We report the first biomimetic conversion of Arnstein tripeptide analogues (1a and 1b) into cis β-lactams (2a and 2b) using O-silylated ketene acetal (3) involving asymmetric induction from the sulfoxide sulfur to the α-carbon. The peptide 1 was treated w