The general pathway to 1,2-monoheterophosphacyclanes via intramolecular S-a
nd N-alkylation of omega-halogenoalkylsubstituted thiophosphoryl and iminop
hosphoryl compounds has been developed. Intramolecular alkylation of 3-and
4-halogenoalkyldiphenylphosphine sulfides results in 1,2 lambda(4)-thiaphos
pholanium and thiaphosphorinanium halogenides. In solution of these compoun
ds the rare ring-chain halogenotropic tautomerism has been observed and inv
estigated in detail. Intramolecular Pishchimuka rearrangement of the esters
of w-halogenoalkylsubstituted thiophosphorus acids was found to be a synth
etic route to 2-oxo-1,2 lambda(5)-thiaphospholanes and thiaphosphorinanes.