Phosphirane-Enabled Synthesis of Aromatic 1<i>H</i>-1,2-Azaphospholes and Phosphinines

Aromatic heteroarenes are essential components of numerous valuable molecules. Herein we present a simple and effective route to access aromatic 1<i>H</i>-1,2-azaphospholes and phosphinines. This method utilizes the ring tension of phosphiranes to convert simple β-chloroethylphosphane and alkynyl imines into these valuable compounds. The nucleophilic addition of the phosphiranide complex to alkynyl imines results in phosphiranes <b>3</b>, which transform into 1<i>H</i>-1,2-azaphospholes under mild conditions. The skeletal editing of 1,2-azaphospholes into phosphinine derivatives was accomplished through a cascade process involving a [4 + 2] cycloaddition and the elimination of a nitrogen moiety.