Synthesis of disubstituted homodiamantanes by acylative ring expansion using benzoyl trifluoromethanesulfonate

Diamantane is a hydrocarbon whose carbon framework is a part of diamond lattices. Acylative ring expansion of 1- and 4-diamantanecarbaldehyde using benzoyl trifluoromethanesulfonate and trifluoromethanesulfonic acid yielded 10-hydroxyhomodiamant-9-yl benzoate and 7-hydroxyhomodiamant-8-yl benzoate, whose skeletal structures are same as pentacyclo[8.3.1.14,13.02,7.06,12]tetradecane.