tert-butyl tetraethylphosphorodiamidite in reactions with alpha,beta-unsaturated dicarbonyl compounds

Abstract

Reactions of tert-butyl tetraethylphosphorodiamidite with benzylideneacetylacetone, benzylideneacetoacetic ester, and benzylidenemalonic ester are studied. It is shown that the reaction pathway significantly depends on the solvent and temperature. The reaction with benzylidenacetylacetone in ether gives rise to a stable diketophosphonate, while the same reaction in boiling benzene involves elimination of diethylamine and yields a phospholene. The reaction with benzylideneacetoacetic ester proceeds analogously, while with benzylidenemalonic ester the corresponding phospholene is formed exclusively.