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.