Highly stereoselective total synthesis of methynolide, the aglycon of the 12-membered macrolide antibiotic methymycin. I. Synthesis of a prelog-djerassi lactone-type chiral intermediate from D-glucose.
The 4-methoxybenzyl (MPM) protectinggroup for hydroxy functions is readily removed with DDQ in dichloromethane containing a small amount of water at room temperature. Under these neutral conditions, several other protecting and functional groups remained unchanged. 3,4-Dimethoxybenzyl (DMPM) groups are more reactive than MPM groups with DDQ. The benzyl (Bn) protectinggroup was removed by catalytic