Synthesis of a methoxy-substituted lactenediyne

The novel lactenediyne 12, characterised by a protected 2-hydroxyethyl chai n at N-11 and by a methoxy group at C-1 was efficiently prepared by a new s trategy involving, as key steps, a Staudinger condensation, a highly diaste reoselective propargylation of a beta-lactam enolate, a chemoselective ozon olysis of a double bond in the presence of a triple one, and a highly diast ereoselective Nozaki-Hiyama ring closure. (C) 2000 Elsevier Science Ltd. Al l rights reserved.