Convenient syntheses of fragment B and linear main skeleton [Fragment A-B-C '] derivatives of an antibiotic, GE 2270 A

Convenient synthesis of the protected linear precursor [Fragment A-BC'] of a macrocyclic antibiotic, GE 2270 A, was achieved by coupling of a 2,3,6-tr isthiazolyl-substituted pyridine skeleton [Fragment A-C'] with a thiazoloyl -thiazole segment [Fragment B]. The Fragment B was synthesized from an appr opriate thioamide and beta -bromo-alpha -oxoalkanoate, the latter of which was first derived by consecutive beta -bromination and hydrolytic removal o f the alpha-(N-Boc)amino group of an alpha -dehydroamino acid ester.