Convergent Synthesis of a Desmethyl Analogue of Amycomycin.

The convergent synthesis of a desmethyl analogue of amycomycin, the aglycon of vancoresmycin, is presented. The central challenge of the convergent strategy was an initial aldol condensation approach, which failed on advanced substrates due to steric hindrance, prompting a revised coupling strategy. The successful route employed nucleophilic vinyl addition, complemented by a Boron-Wittig olefination to construct sterically congested vinyl boronates. A late-stage O- to C-acyl transfer on a complex 3-acyl tetramic acid was essential for the efficient assembly of the complete skeleton of desmethyl amycomycin.