The reaction of benzothiazolyl substituted α-phosphorylmethyl sulfoxides with several amines

We have examined the reactivities of α-phosphorylmethyl benzothiazolyl sulfoxides in the thermolyses and in the presence of several amines, such as aniline, benzylamine, piperidine, morpholine, and pyrrolidine. Thermolyses of the derivatives in the presence of 2,3-dimethyl-1,3-butadiene afforded 2-phosphoryl substituted 4,5-dimethyl-3,6-dihydro-2H-thiopyran S-oxide. In the reaction with amines, the complex product mixture, which contains α-phosphorylmethyl benzothiazolyl sulfides (2 and 5), α-phosphorylmethyl disulfides (15 and 16), and 2-amino substituted benzothiazole 14 was found to be formed besides the target phosphinecarbothioamides. Several mechanistic studies were performed to elucidate the formation mechanism, particularly for deoxygenated products from the starting sulfoxides, i.e., 2 and 5 from 3 and 6, respectively.