A formal [3+2] alkene addition to benzhydrol cations.: A practical and mild methodology for the synthesis of substituted 1-arylindanes and related compounds

We report the single step synthesis of several 1-arylindanes in good yield via a formal [3 + 2] atom cycloaddition. The success of this formal cycloaddition relies on the Lewis acid activation of a bibenzylic alcohol in the presence of an alkene. The cation generated from the alcohol can be trapped by the alkene to afford a new benzylic cation which can then undergoes cyclization leading to 1-arylindanes with three stereogenic centres.