Solvent-controlled difluoromethylation of 2′-hydroxychalcones for divergent synthesis of 2′-difluoromethoxychalcones and 2,2-difluoro-3-styryl-2,3-dihydrobenzofuran-3-ols
The solvent-controlled difluoromethylation of 2'-hydroxychalcones using the shelf-stable reagent difluoromethylene phosphabetaine for divergent synthesis of 2'-difluoromethoxychalcones and 2,2-difluoro-3-styryl-2,3-dihydrobenzofuran-3-ols is developed. When difluoromethylation was performed in p-xylene, 2'-difluoromethoxychalcones were the major product with 47-97% yields, while 2,2-difluoro-3-styry1-2,3-dihydrobenzofuran-3-ols were obtained in 21-75% yields using acetonitrile as solvent. A plausible reaction mechanism was proposed according to the experimental results. (C) 2015 Published by Elsevier B.V.