Bridgehead aldehydes of bicyclo [3.2.] loctane (11a), bicycio-[3.3. 1] nonane (12a), and bicyclo [3.2. 2] nonane (13a) have been subjected toacylative ring-expansion by using benzoyl trifluoromethanesulfonate (trif-late) to give mixtures of two or three bicyclic 1, 2-diol monobenzoates containing the hydroxyl group on the bridgehead carbon. Control experiments have shown that the reaction is kinetically controlled. The direction of the ring ...