Synthetic Studies Towards the B,C,D,E Fragment of Antibiotic CP44, 161

Abstract

The synthesis of polyethers 32 and 33 from tricyclic bis-spiroacetal aldehyde 27 and E-bromide 7 are described. A key step in the synthetic strategy involved the oxidative cyclisation of a bicyclic hydroxyspiroacetal 22a,b to a cis bis-spiroacetal un