Mechanism of the exchange reaction of halodiazirines with nucleophiles revisited. Synthesis of neutral, mono- or dicationic 4-16-membered phosphorus heterocycles

Trimethyl-, diphenylmethyl-, triphenyl-, diphenylthienyl-, and bis(dimethylamino) (isopropylthio)phosphine react with bromophenyldiazirine (1) giving cationic N,N'-bis(phosphine) adducts 2a-c, 7, and 8 in 83-95% yields. Depending on the experimental conditions used, addition of 1,2-bis(diphenylphosphino)ethane to 1 leads to dicationic 14- and monocationic seven-membered heterocycles 3 (90% yield) and 4 (60% yield) or cationic N,N'-bis(diphosphine) adduct 5 (86% yield); similarly, when diphenyl(isopropylthio)phosphine is used, competitive reactions occur, leading to cationic five-membered heterocycle 9 (34% yield) and/or N,N'-Bis(diphosphine) adduct 10 (65% yield). 1,3-bis(diphenylphosphino)propane also reacts with 1, affording dicationic 16-membered heterocycle 6 (75% yield). Addition of bis(diisopropylamino)(trimethylstannyl)phosphine to 1 gives rise to a mixture of N-[(trimethylstannyl)imino]bis(diisopropylamino)bromophosphorane (11) (32%), 2,2-bis(diisopropylamino)-4-phenyl-1,3,2 lambda(5)-diazaphosphete (12) (26% yield), 1,3,5,2 lambda(5)-triazaphosphinine 13 (3% yield), benzonitrile (35%), and bromotrimethylstannane (60%). The mechanisms involved in these reactions are studied.