Preparation of 2,2'-dihydroxytriphenylmethanes using metal phenolates with aromatic aldehydes

The reactions of oxophilic metal phenolates having electron-donating substituents (1a-c) with aromatic aldehydes (2, 3) were selectively condensed at the ortho-position of the starting phenol to afford 2,2'-dihydroxytriphenylmethanes (8-11). This method was also applicable to the preparation of bisphenols (12-17) starting with naphthaldehydes (4, 5) and pyridinecarboxaldehydes (6, 7), but in low yields. In the case of these aldehydes (4-7), satisfactory yields could be obtained by sonication.