Reaction of 3a,6a-Diaza-1,4-diphosphapentalene with Substituted Acetylenes

Abstract

The reaction of 3a,6a-diaza-1,4-diphosphapentalene with 1-bromo-2-phenylacetylene has led to the formation of 1,1-bis(phenylethynyl)- and 1,4-dibromo-3a,6a-diaza-1,4-diphosphapentalene. The first has been also prepared via a different route by the reaction of 1,4-dichloro-3a,6a-diaza-1,4-diphosphapentalene with lithium phenylacetylenide in 96% yield. No isomeric 1,4-bis(phenylethynyl)-DDP has been formed in this reaction. The reaction in the 3a,6a-diaza-1,4-diphosphapentalene–[Ph₃PC≡CPh]Br–carbazole three-component system proceeds as addition of carbazole to the initially formed complex of 3a,6a-diaza-1,4-diphosphapentalene with [Ph₃PC≡CPh]Br with the rupture of the P–N bond. The products and intermediates of the reaction have been simulated by B3LYP/6-31+G(d) method.