Synthesis of Sydnone Compounds Substituted by Heteroatom Groups at the 4-Positions

Abstract

A general method for the introduction of heteroatoms to the 4-position of a sydnone ring was developed. Various 4-alkylthio- and 4-arylthiosydnones were prepared in excellent yields by the reaction of 3-aryl-4-lithiosydnones (2) with dialkyl and diaryl disulfides. Treatment of 2 with diaryl diselenides, diphenylphosphinous chloride, and arsenic trichloride provided 3-aryl-4-(arylseleno)sydnones, (3-aryl-4-sydnonyl)diphenylphosphine and tris(3-aryl-4-sydnonyl)arsine, respectively, in good yields. It was also found that the reactivity of sydnonyl anions derived from 2 was quite different in some cases from that of the corresponding ordinary aromatic analogues, though the sydnone ring has a somewhat aromatic nature.