preparation by hydrogenolysis of 2,2′,4′-tris-(benzyloxy)-4-methoxy-6,6′-dimethylbenzophenone (SM) in the presence of 10% Pd/C in ethyl acetate containing concentrated hydrochloric acid (5 drops). SM was obtained by FriedelCrafts acylation of 3,5-bis(benzyloxy)toluene with 2-(benzyloxy) -4- methoxy-6-methylbenzoic acid in the presence of trifluoroacetic anhydride in refluxing ethylene dichloride for 5.
