1-Methyl-2, 5-diphenyl-1, 4-dithiinium tetrafluoroborate (2) underwent selective abstraction of H-3 in aqueous phosphate buffer at pH 6.8 to yield the ring cleavage product (Z)-l- (phenylethynylthio)-2-(methylthio)-l-phenylethylene (4). Methylation of 3-nitro-2, 5-diphenyl- 1, 4-dithiin(5) with MeI-AgBF, yielded as the major product l-methyl-6-nitro-2, 5-diphenyl-l, 4- dithiinium tetrafluoroborate (8), which also underwent ring cleavage in acetonitrile on an ...
