Three types of Sb^Ⅲ reagents were studied. They are: (1)the compounds containing mercapto group, (2) Caille ands Viel reagents and (3) the compounds containing two phenolic groups in adjacent positions.It was shown experimentally that the first two types of reagents give reactions with very low selectivities. Moreover, the selectivities could not be improved by merely varying the structure of the organic compounds.