Enantioselective total syntheses of bengamides B and E

Convergent total syntheses of two sponge-derived cyclolysine derivatives - bengamides B (1) and E (2) - have been accomplished. The polyhydroxylated side chain common to both natural products was obtained from L-glucose and the hydroxylated caprolactam moiety of 1 was prepared using Evans' oxazolidinone chemistry. In the course of this work a new Horner-Emmons reagent incorporating one of Evans' chiral auxiliaries was developed.