| Abstract
| - Various glyoxal hydrates have been reacted with Deoxofluor [(CH3OCH2CH2)2NSF3]. In concentratedsolutions of dichloromethane, Deoxofluor (1) efficiently fluorinates a variety of glyoxal hydrates,RCOCHO·H2O (R = 4-methoxyphenyl, 3,4-methylenedioxyphenyl, 4-methylphenyl, 4-fluorophenyl,phenyl, 2-thienyl, methyl) (6a−g) to form polyfluoroethers 7a−g and 8a−g as meso and racemicmixtures (∼1:1) in good yields. The meso and racemic compounds were separated by flashchromatography and characterized. When the reactant comprised two different glyoxal hydrates,mixed polyfluoroethers (9h−j) were observed as the major products. The yields of the mixedpolyfluoroethers depend on the ratio of the two different glyoxal hydrates used. Reactions of someother hydrates, such as hydrindantin dihydrate (10) and 1,1,1,5,5,5-hexafluoro-2,2,4,4-pentanetetrol(11), were also studied with Deoxofluor to give a cyclic polyfluoroether (12) and β-ketoamine (13),respectively. When the reactions of 6a−d were carried out under very dilute conditions, difluoroaldehydes (14a−d) or tetrafluoroalkanes (15a−d) were formed rather than polyfluoroethers.Reactions of concentrated solutions of nonhydrated glyoxals (16k−m) in methylene chloride withDeoxofluor produced the tetrafluoroalkanes (18k−m) in good yields with only trace amounts ofdifluoroaldehydes (17k−m) being found. The structures of 7a (meso), 8b (racemic), and 12 havebeen confirmed by single-crystal X-ray analysis.
|
