IMIDAZOLE-ASSISTED INTRAMOLECULAR PHENOXYTHIOCARBONYLATION OF TERTIARY ALCOHOLS - A KEY REACTION FOR THE DEOXYGENATION OF ALPHA-TRIFLUOROMETHYLARYLMETHYL ALCOHOLS

The deoxygenation of alpha-trifluoromethylarylmethyl alcohols failed u nder catalytic hydrogenation conditions. However, these alcohols can b e deoxygenated via their thionocarbonate intermediates followed by hom olytic reductive cleavage of the C-O bond. The formation of the phenyl thionocarbonate esters is sterically dependent. Consequently, seconda ry alpha-trifluoromethyl arylmethyl alcohols can be smoothly converted to thionocarbonates, but tertiary alcohols cannot. Exceptions to this lack of reactivity are the aryl 4-substituted imidazolyl trifluoromet hyl carbinols, which do form the thionocarbonates under these conditio ns.