ON THE FORMATION AND SOLVOLYSIS OF ARYL-2,2-DIFLUORO-6-METHYL-1,3,2-(2H)-DIOXABORINES

The condensation of aryl methyl ketones 6 with acetic anhydride 4a in the presence of the boron trifluorideacetic acid adduct 7 gives rise t o the formation of aryl-2,2-difluoro-6-methyl-1,3,2-(2H)-dioxaborines 8 in satisfactory yields. The stable aryl-2,2-difluoro-6-methyl-1,3,2- (2H)-dioxaborines 8 can be transformed by hydrolysis into the correspo nding aroylacetones 9. The reaction was optimized so as to avoid the f ormation of by-products, such as 2,4-diaryl-6-methylpyrylium tetrafluo roborates 11 or self-condensation products. (C) 1997 John Willey & Son s, Inc.