Reductive Rearrangement of a 1‐Phospha‐2‐azanorbornene

The reduction of the 1‐phospha‐2‐azanorbornene derivate endo‐1 with lithium aluminium hydride leads to an unprecedented 1‐phosphabicyclo[3.2.1]octa‐2,5‐diene, while a phospholide anion is formed with lithium. The latter can be protonated resulting in formation of an unusual 2H‐phosphole dimer. Furthermore, 3H‐phospholes, previously assumed to have no synthetic relevance as intermediates, were proposed to act as dienophile in the dimerisation of 3,4‐dimethyl‐1‐phenylphosphole at elevated temperatures based on theoretical calculations.