Reactions of benzyl carbinols with fluorosulfuric acid

A series of benzyl carbinols have been reacted with HSO 3 F at -78 °C, the solutions quenched, and the products isolated and identified. A variety of reaction modes occur including reduction (3-methyl- and 4-methyl-l-benzylcyclohexanol), rearrangement and cyclization (1-benzyl-2-methylcyclohexanol, 6-benzylspiro[4.5]decan-6-ol, 1-benzyl-trans-decalin-l-ol, 2-benzylcamphenilol, 2-benzylfenchol, 3-methyl-l-phenylbutan-2-ol, spiro[3-exo-benzylbicyclo[2.2.1] heptan-3-endo-ol-2,T-cyclopentane]), and ring expansion (2-benzylnorbornanol). At higher temperatures fluorosulfonation of the product aryl ring can occur. The reaction mechanisms are discussed and that of the benzylnorbornyl ring expansion unambiguously determined by a series of deuterium labeling experiments.