Simple and efficient preparation of sterically protected 1,4-diphosphafulvenes

A new synthetic method for sterically protected 1,4-diphosphafulvenes (2-methylene-2,3-dihydro-1H-[1,3]diphospholes) has been developed starting from (arylethynyl)phosphines and ca. 0.25 molar amount of butyllithium. The catalytic mechanism of the reaction is discussed based on the results of deuterium-labelling experiments.