Dihydro-3-(triphenylphosphoranylidene)-2,5-thiophendione: a convenient synthon for the preparation of substituted 1,4-thiazepin-5-ones and piperidinones via the intermediacy of thioacids

Abstract

Reaction of thiomaleic anhydride with triphenylphosphine gives the title compound which undergoes reaction with a variety of aldehydes to give a range of alkylidene thiomaleic anhydrides (substituted monothio itaconic anhydrides). Subsequent treatment with tert-butoxycarbonylaminosubstituted thiols, or under radical conditions with tert-butoxycarbonylamino-substituted alkyl halides results in a series of substituted monothiomaleic anhydrides, that on exposure to trifluoroacetic acid and then base lead to thiocarboxyl substituted 1,4-thiazepin-5-ones and piperidinones, respectively, that are ultimately trapped by reaction with 2,4-dinitrobenzenesulfonamides to give the corresponding amides.

Facile Synthesis of 3-N-Alkyl Pyrimidin-2,4-diones from N-Sulfonyloxy Maleimides and Amines

“…In so far as the N -hydroxy maleimides are assembled directed from the corresponding maleic anhydrides, for which a variety of facile synthetic methods are available, this novel pyrimidindione synthesis complements and extends the existing uses of cyclic anhydrides and thioanhydrides − in formal multicomponent processes. This novel synthesis of pyrimidindiones also complements existing methods for the synthesis of this class of heterocycles and the use of the Biginelli multicomponent synthesis of dihydro­pyrimidines, , and other multicomponent approaches to pyrimidines themselves …”