AN IMPROVED SYNTHESIS OF β-KETO ESTER UNITS IN DIDEMNINS, USING 2,2'-CARBONYL-BIS(3,5-DIOXO-4-METHYL-1,2,4-OXADIAZOLIDINE).

Article abstract of DOI:10.1016/0040-4039(88)85253-5

Activation of N-protected α-amino acids and O-protected α-hydroxy acids with 2,2'-carbonyl-bis(3,5-dioxo-4-methyl-1,2,4-oxadiazolidine) 6 provide a stable activated intermediate 7 suitable for the synthesis of β-keto ester 8.This activation was used in th