New Convenient Synthesis of Homoisoflavanones and (±)-Di-O-methyldihydroeucomin

Upon reaction of 1-(2-hydroxyphenyl)-3-phenylpropane-1-ones (2'-hydroxydihydrochalcones) with dimethylaminodimethoxymethane in boiling toluene, the corresponding 3-benzylchromones are obtained in excellent yields. These latter lead to 3-benzylchroman-4-ones (bomoisoflavanones) by catalytic hydrogenetion. These reactions were applied to the synthesis of (+/-)-3-benzylchroman-4-one and (+/-)-3(4-methoxybenzyl)-5,7-dimethoxychroman-4-one, (+/-)-di-O-methyldihydroeucomin.