Asymmetric α-hydroxylation of a lactone with vinylogous pyridone by using a guanidine-urea bifunctional organocatalyst: catalytic enantioselective synthesis of a key intermediate for (20S)-camptothecin analogues.

Asymmetric α-hydroxylation of a lactone with vinylogous pyridone by using a guanidine-urea bifunctional organocatalyst: catalytic enantioselective synthesis of a key intermediate for (20S)-camptothecin analogues.