Studies of reactions of dimethylphosphoramidic difluoride withtrans-2-(N,N-dialkylamino)cycloalkanols in the presence of various sulfur-containing nucleophiles

Abstract

The reactions of dimethylphosphoramidic difluoride (1) withtrans-2-(N,N-dialkylamino)cycloalkanols were studied in the presence of various sulfur-containing nucleophiles and Et3N. WhenO,O-diisopropyl thiophosphoric acid was used as a nucleophile, the correspondingO,O-diisopropylS-[2-(N,N-dialkylamino)cycloalkyl] thiophosphates were obtained in satisfactory yields. The direction of this reaction in the presence ofO-isopropyl toluenephosphonothioic acid depends on the pKa of aminoalcohol, namely, the amount ofO-isopropyl tolylphosphonofluoridate that was formed along withO-isopropylS-[2-(N,N-dialkylamino)cycloalkyl] tolylphosphonothioates was increased as the pKa increased. The reactions of compound1 withtrans-2-(N,N-dialkylamino)cycloalkanols and thioacetic acid afforded 2-(N,N-dialkylamino)cycloalkanethiols, certain of which were readily oxidized to the corresponding disulfides. In the case of potassium ethyl xanthate, the composition of the reaction products depends on the nature of aminoalcohol. X-ray diffraction analysis ofS-(2-piperidinocyclohexyl)N,N-dimethyldithiocarbamate demonstrated that this compound exists as thetrans isomer. This fact supports the reaction mechanism, which we have suggested previously and which involves the formation of aziridinium cations followed by their opening under the action of nucleophilic agents.