Amino-acids and peptides. Part VII. The synthesis of the fourteen-membered cyclodepsipeptidesD-D-,L-L-, andD-L-cyclodi-(β-seryloxypropionyl)

Abstract

The synthesis of cyclodi-[β-(O-t-butyl-D-seryloxy)propionyl] and of cyclodi-[β-(O-t-butyl-L-seryloxy)propionyl] has been achieved by cyclodimerisation. The related meso(D-L)-form of the fourteen-membered cyclodepsipeptide has been prepared by cyclisation of the corresponding linear depsipeptide. These syntheses confirm that cyclodimerisation of recemic intermediates gives, predominantly, the meso-form of the product. The analogous cyclodepsipeptides with unprotected seryl residues have been prepared by the action of acid on the O-t-butyl derivatives.