Annulation of Thioimidates and Vinyl Carbodiimides to Prepare 2-Aminopyrimidines, Competent Nucleophiles for Intramolecular Alkyne Hydroamination. Synthesis of (-)-Crambidine.

A convergent synthesis of (−)-crambidine is reported. The sequence capitalizes on two novel key transformations, including a [4+2] annulation of thioimidates with vinyl carbodiimides and an alkyne hydroamination employing 2-aminopyrimidine nucleophiles.