1-Bromo-3, 4-dimethyl-3-phospholene quaternizes readily with functional organic halides Z- (CH2) nX with Z= OR, SR, C (O) R, CH (OR) 2, COOR, CONR2, CN, n= 1 or 2, and X= Cl or Br. The adducts thus obtained are formally related to the diene-dihalophosphine