A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

We present a successful deoxygenation reaction of ortho-1,3-dithianylaryl(aryl)methanols which enables a selective removal of the secondary hydroxy group in presence of the 1,3-dithianyl moiety under reductive conditions. This reaction proceeds well with ZnI2/Na(CN)BH3 in dichloroethane or benzene for both unsubstituted and substituted aryls (by electron-rich groups). This is leading to formyl-protected diarylmethanes with potential application in the synthesis of new pharmaceuticals and optoelectronic materials. This synthetic approach gives an access to a wide variety of functionalized ortho-1,3-dithianylaryl(aryl)methanes in 26–95% yields and is recommended for the substrates containing sulfur atoms, for which transition metal-induced reactions fail.