Synthesis of a methoxy-substituted lactenediyne

The novel lactenediyne 12, characterised by a protected 2-hydroxyethyl chain at N-11 and by a methoxy group at C-1 was efficiently prepared by a new strategy involving, as key steps, a Staudinger condensation, a highly diastereoselective propargylation of a β-lactam enolate, a chemoselective ozonolysis of a double bond in the presence of a triple one, and a highly diastereoselective Nozaki–Hiyama ring closure.