Functionalization of Bis-Diazaphospholene P-P Bonds with Diverse Electrophiles

Readily prepared bis-diazaphospholenes are shown to react with several classes of electrophiles, resulting in cleavage of the phosphorus-phosphorus bond and formation of functionalized diazaphospholenes. Phosphorus – sp³ or sp² carbon and phosphorus – sulfur bonds were formed using this protocol. Experimental evidence with aryl and alkyl halides suggests the intermediacy of radicals in some cases, however other evidence suggests either radical or polar mechanisms may be operative for certain substrates, with a dependence on reaction conditions. In some cases, the substituted diazaphospholenes can transfer the substituent to electrophiles via previously unknown reactions. These results show diazaphospholene dimers are potent participants in radical chemistry at room temperature without requiring chemical initiators.