2‐Chloro‐2<i>H</i>‐phosphirene/1‐Chloro‐1<i>H</i>‐phosphirene Isomerization by [1,3]‐Chlorine Shift

Abstract

The contrasting behavior of nitrogen and phosphorus is shown by the product of reaction (a). Whereas only the 2H isomers of azirines are known to be stable, the initial 2H products of this thermally induced carbene addition undergo [1,3] chlorine shift to afford the 1H isomers 1. The stability of 1 might be due to a decrease in its potentially antiaromatic character by non-planarity at phosphorus. Nucleophilic substitutions provide a large variety of functionalized phosphirenes from 1.