Dideoxy 6,6-difluoro-3-0-methyl

Abbreviations All, allyl MP, dimelhylaminopyridine or 2,4,6-trimelhylpyridine MOM, methoxy-methyl Piv, pivaloyl Tr, trityl other abbreviations are the same. Obtained accompanied with the 3,4-0-( methyl orthoacetyl)-a-D-galactoside the 0-deacetyl derivative was also reported. Inserted as a reference reaction. A mixture of two diastereoisomers. On hydrolysis (R = F), 3,6-dideoxy-3,6-difluoro-D-glu-copyranose is formed. Methanolysis gives methyl 3-deoxy-3-fluoro-a-D-galactopyranoside. 

Coupling constants (4/f,h) have been observed in a few instances where fluorine is attached to sp2-hybridized carbon, as, for example, in derivatives of 3-deoxy-3-C-(fluoromethylene)-l,2 5,6-di-O-isopropyli-dene-a-D-ribo- and -xylo-furanose, where JF, h-2 and 4/F, h-4 occur254,264 in the range of 0.5-5.5 Hz, and in 5,6-dideoxy-6,6-difluoro-l,2-0-isopropylidene-3-0-methyl-a-D-xylo-hex-5-enofuranose,251 where 4JFete, h-4 = 2.0 Hz and VFtran. h-4 = 1.5 Hz (cis and trans, relative to H-5). 

Values for 7f.c have been recorded251 for fluorine attached to sp2-hy-bridized carbon, as in 5,6-dideoxy-6,6-difluoro-l,2,0-isopropylidene-3-0-methyl-a-D-3cyio-hex-5-enofuranose, where lJftC = 285 Hz. The signs of the 7f,c values both for the pyranosyl and the furanosyl fluorides were found to be negative.278... 

Methyl 5,6-dideoxy 6,6-difluoro-2,3-0-isopropylidene-a-D-riho-hex-5-enofuranoside... 

Chloro-5,6-dideoxy-5,6-difluoro-l,2-0>isopropylidene>3-0-methyl-a- D-xylo-... 

Methyl 4,6-0-benzylidene-2,3-dideoxy-3,3-difluoro-a-D-erythro-hexopyranoside (0.70g, 2.5 mmol) was dissolved in a 0.1 N ethanolic solution of hydrochloric acid and stirred at room temperature for 1 day. The solution was then neutralized by addiing solid sodium bicarbonate. The solids were filtered, the solvent was then evaporated to dryness and residue dissolved in 5 ml of pyridine and 1.5 ml of benzoyl chloride. The solution was stirred for 10 h, poured into ice-water (300 ml), extracted with dichloromethane (3 x 100 ml), washed with a saturated solution of sodium bicarbonate, dried and evaporated, to give 0.86 g (2.1 mmol, 85%) of methyl 4,6-di-0-benzoyl-2,3-dideoxy-3,3-difluoro-a-D-erythro-hexopyranoside. 

BF3OEt2 (0.060 ml, 0.48 mmol as a solution of 48% in BF3) and phenylselenol (0.064 ml, 0.60 mmol) were added to a stirred solution of methyl 4,6-di-O-benzoyl-2,3-dideoxy-3,3-difluoro-a-D-erythro-hexopyranoside (100 mg, 0.24 mmol) in anhydrous dichlormethane (2 ml). The solution was heated to reflux for 3 h, neutralized by dropwise addition of pyridine and evaporated to dryness. The residue was purified by column chromatography (hexane/ethyl acetate 10/1) to afford 92 mg (72%) of phenyl 4,6-di-0-benzoyl-2,3-dideoxy-3,3-difluoro-l-seleno-a-D-erythro-hexopyranoside as an anomeric mixture. 

Acetamido-2,6-anhydro-3,5-dideoxy-2,3-difluoro-D-ara6 o-L-ta/o-nononic acid 5-Acetamido-2,6-anhydro-3,5-dideoxy-4-C-methyl-D-eo /iro-L-a/(ro-nononic acid 5-Acetamido-2,6-anhydro-3,5-dideoxy-4-C-methyl-D-eo tAra-L-manno-nononic acid... 

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