Organofluorine compounds and fluorinating agents, 15. O ‐difluoromethylations of monosaccharides by trifluoromethylzinc bromide

1,2:3,4‐Di‐ O ‐isopropylidene‐α‐ D ‐galactopyranose ( 1 ), methyl 2‐ O ‐(cyclohexylcarbamoyl)‐3,4‐ O ‐(2,2,2‐ trichloroethylidene)‐α‐ D ‐altropyranoside ( 4 ), methyl 4,6‐ O ‐benzylidene‐2‐ O ‐to‐syl‐α‐ D ‐glucopyranoside ( 6 ), and methyl 4,6‐ O ‐benzylidene‐α‐ D ‐glucopyranoside ( 8 ) were O ‐difluoromethylated with tri‐fluoromethylzinc bromide (ZnBrCF 3 . 2 CH 3 CN) in a convenient procedure giving the difluoromethyl ethers 2, 5, 7, 9 , and the bis(difluoromethyl) ether 10 in moderate yields. The 6‐ O ‐difluoromethyl‐1,2:3,4‐di‐ O ‐isopropylidene‐ α‐ D ‐galacto‐pyranose ( 2 ) was deprotected by treatment with aqueous tri‐fluoroacetic acid forming 6‐ O ‐difluoromethyl‐ D ‐galactopyranose ( 3 ).