A Mild Lewis-Acid-Catalyzed Method for Head-to-Tail Dimerization or Cyclization of tert-Alcohols

摘要

A mild and practical method is developed for the efficient synthesis of (1,1-dimethyl-3-phenylbut-3-enyl)benzenes and indanes promoted by Lewis acid, starting from tert-benzyl alcohols. The reaction is temperature dependent and furnished the products with excellent regioselectivity. In the case of simple dimerization, Markovnikov head-to-tail coupling took place. On the other hand, reaction at elevated temperatures gave indanes through subsequent Friedel-Crafts cycloalkylation. Significantly, even electron-rich aromatic systems were compatible for the formation of indanes, which would not be feasible by earlier reports, thus, revealing the advantage of the mild nature of the present protocol.