Fucopyranoside methyl 3,4-0-isopropylidene

Methyl-D-fucose has been prepared by two methods.68 In the first, methyl a-D-galactopyranoside was converted into the 6-tosyl derivative, from which by condensation with acetone methyl 3,4-isopropylidene-6-tosyl-a-D-galactopyranoside (LXIV) was obtained. Methylation gave the corresponding 2-methyl ether which was converted into the 6-deoxy iodide (LXV) by heating with sodium iodide in acetone solution at 140°. Reduction with Raney nickel gave sirupy methyl 2-methyl-3,4-isopro-pylidene-a-D-fucopyranoside (LXVI) from which 2-methyl-D-fucose was obtained on hydrolysis. 

In the second process methyl 3,4-isopropylidene-a-D-fucopyranoside was methylated to give crystalline methyl 2-methyl-3,4-isopropylidene-a-D-fucopyranoside, from which 2-methyl-D-fucose was obtained by hydrolysis with sulfuric acid. The sugars obtained by both routes were identical. 

Methyl-L-fucose has been prepared in an analogous manner to that of its enantiomorph by the methylation of methyl 3,4-isopropylidene-o-L-fucopyranoside,71,76 followed by hydrolysis. 

Methyl 3,4-isopropylidene-a-L-fucopyranoside was converted into the 2-tosyl derivative (LXXXII). After removing the isopropylidene residue with methanolic hydrogen chloride, methyl 3,4-dimethyl-2-tosyl-a-L-fucopyranoside (LXXXIII) was obtained by methylation with methyl iodide and silver oxide. Reductive fission of the p-toluenesulfonyl residue with sodium amalgam, followed by hydrolysis, gave 3,4-dimethyl-L-fucose83 (LXXXIV). 

Brimacombe and How reduced methyl 3,4-0-isopropylidene-2,6-di-O-p-tolylsulfonyl-a-D-galactopyranoside with lithium aluminum hydride in tetrahydrofuran, to provide methyl 3,4-O-isopropylidene-2-0-p-tolylsulfonyl-a-D-fucopyranoside in 54% yield. In later reductions of closely related compounds, the solvent chosen was ether-benzene methyl 3-0-benzyl-2-deoxy-6-0-p-tolylsulfonyl-a-D-Ii/xo-hexopyranoside afforded the corresponding 6-deoxy compound which, on methylation, debenzylation, and acid hydrolysis, gave 2,6-dideoxy-4-O-methyl-D-Zi/Jco-hexose (chromose A). An improved synthesis of this sugar involved the reduction, in ether—benzene (1 1), ofmethyl 2-deoxy-4-0-methyl-3,6-di-0-p-tolylsulfonyl-a-D-/i/xo-hexopyranoside to methyl 2,6-dideoxy-4-0-methyl-a-D-Z /xo-hexopy-ranoside in 25% yield a synthesis of 3-0-acetyl-2,6-dideoxy-D-Z /xo-hexose (chromose D) was effected by way of reduction in ether-benzene (2 1) of methyl 2-deoxy-6-0-p-tolylsulfonyl-a-D-Zyxo-hexo-pyranoside to the corresponding 6-deoxy compound in 27% yield, followed by partial acetylation and acid hydrolysis. 

The synthesis of 2-methyl-D-fucose was carried out first directly from D-fucose. Methylation of methyl 3,4-isopropylidene-D-fucopyranoside (XI) and hydrolysis of the glycosidic methyl group in the product (XII) led directly to the desired sugar (XIII). 

Tosyl Methyl 3,4-0-isopropylidene-2-0-tosyl-a-L-fucopyranoside C17H24O7S 372.438 Cryst. (MeOH). Mp 182°. [a] / -146 (c, 1.0 in CHCI3). 

Methyl 4-0-acetyl-6-deoxy-2,3-0-isopropylidene-a-L-talopyranoside, D-372 Methyl 4-C-acetyl-6-deoxy-2,3-0-methylene-D-galactonate, A-15 Methyl 3-0-acetyl-2,4-diamino-2,4,6-trideoxy-a-D-idopyranoside, D-480 Methyl 5-0-acetyl-2,3-di-0-benzoyl-a-D-aral5inofuranoside, M-152 Methyl 3-0-acetyl-2,4-dibenzoyl-6-bromo-6-deoxy-a-D-altropyranoside, B-60 Methyl 4-0-acetyl-2,3-di-0-benzoyl-a-L-rhamnopyranoside, M-207 Methyl 4-0-acetyl-2,3-di-0-benzyl-a-L-fucopyranoside, M-183 Methyl 3-0-acetyl-2,4-di-0-benzyl-a-L-fucopyranoside, M-183 Methyl 2-0-acetyl-3,4-di-0-benzyl-a-L-fucopyranoside, M-183 Methyl 6-0-acetyl-2,3-di-O-benzyl-a-D-galactopyranoside, M-185 Methyl 6-0-acetyl-2,3-di-O-benzyl-a-D-mannopyranoside, M-204 Methyl 3- 0 -acetyl-2,4-dideoxy-2-dibenzyIamino-a-DL-/Areo -pentopyranoside, A-412... 

Methyl 2-0-acetyl-3,4-0-isopropylidene-p-D-arabinopyranoside, M-153 Methyl 2-0-acetyl-3,4-0-isopropylidene-p-L-arabinopyranoside, M-I97 Methyl 2-0-acetyl-3,4-0-isopropylidene-a-L-fucopyranoside, M-19S Methyl 2-0-acetyl-3,4-0-isopropylidene-a-D-galactopyranosiduronamide, M-188... 

Methyl 2-0-benzyl-3,4-0-isopropylidene-p-L-arabinopyranoside, M-197 Methyl 2-0-benzyl-3,4-O-isopropylidene-a-L-fucopyranoside, M-198 Methyl 3- 0 -benzyl-1,2- O -isopropylidene- p-L-idofuranuronate, 1-12 Methyl 5-0-benzyl-2,3-0-isopropylidene-a-D-lyxofuranoside, 1-70 Methyl 5-O-benzyl-2,3-O-isopropylidene-a-D-mannofuranoside, 1-71 Methyl 6-O-benzyl-2,3-O-isopropylidene-a-D-mannofuranoside, 1-71 Methyl 4-O-benzyl-2,3-O-isopropylidene-a-L-rhamnopyranoside, M-207 Methyl 2-O-benzyl-3,5-O-isopropylidene-a-D-xylofuranoside, M-216 Methyl 2-O-benzyl-3,5-O-isopropylidene-p-D-xylofuranoside, M-216 Methyl 3-0-benzyl-2-0-methyl-a-D-allopyranoside, M-148 Methyl 5-0-benzyl-2-0-methyl-a-D-glucofuranosidurono-6,3-lactone, G-539 Methyl 5-0-benzyl-2-0-methyl-p-D-glucofuranosidurono-6,3-lactone, G-539 Methyl 2,6-0-benzyl-3-0-methyl-a-D-mannopyranoside, M-271 Methyl 3-0-benzyl-2-O-methyl-6-0-tosyl-a-D-allopyranoside, M-148 Methyl 5-0-benzyl-3-0-methyl-a-D-xylofuranoside, M-216 Methyl 3-0-benzyl-a-L-rhamnopyranoside, M-207 Methyl 4-0-benzyl-a-L-rhamnopyranoside, M-207 Methyl 3-0-benzyl-p-L-ribofuranoside, M-208 Methyl 3-O-benzyl-4-O -(2,3,4-tri-O-benzyl-p-D-xylopyranosyl)-p-D-xylopyranoside, X-80... 

Methyl 2,3-di-O-benzyl-5,6-0-isopropylidene-a-D-galactofuranoside, M-184 Methyl 2,3-di-O-benzyl-5,6-0-isopropylidene-p-D-galactofuranoside, M-184 Methyl 2,6-di-O-benzyl-a-D-mannofuranoside, M-203 Methyl 2,3-di-0-benzyl-a-D-mannopyranoside, M-204 Methyl 3,6-di-O-benzyl-a-D-mannopyranoside, M-204 Methyl 2,3-di- O -benzyl-5- O -niesyl-6-0 -trityl- p-D-glucofuranoside, M-189 Methyl 2,4-di-O-benzyl-3-0-methyl-a-L-fucopyranoside, M-183 Methyl 3,4-di-0-benzyl-2-0-methyl-a-L-fucopyranoside, M-183 Methyl 3,4-di-0-benzyl-2-0-methyl-a-D-rhamnopyranoside, M-207 Methyl 3,4-di-O-benzyl-a-D-rhamnopyranoside, M-207 Methyl 2,3-di-0-benzyl-a-L-rhamnopyranoside, M-207 Methyl 2,4-di-O-benzyl-a-L-rhamnopyranoside, M-207 Methyl 3,4-di-O-benzyl-a-L-rhanmopyranoside, M-207 Methyl 3,5-di-0-benzyl-a-D-ribofnranoside, M-208 Methyl 2,3-di-0-benzyl-6-0-tosyl-a-D-altropyranoside, M-149 Methyl 2,3-di-O-benzyl-6-O-tosyl-p-D-galactofuranoside, M-184 Methyl 2,4-di-0-benzyl-3-0-(2,3,4-tri-0-acetyl-a-L-rhanmopyranosyl)-a-D-xylopyranoside, R-77... 

Methyl 2,3-0-isopropylidene-4-O-methyl-a-D-lyxopyranoside, M-202 Methyl 2,3-0-isopropylidene-6-O-methyl-a-D-mannopyranoside, M-200 Methyl 2,3-0-isopropylidene-5-0-methyl-a-L-rhamnofuranoside, M-206 Methyl 2,3-0-isopropylidene-5-0-methyl-p-L-rhamnofuranoside, M-206 Methyl 2,3-0-isopropylidene-4-O-methyl-a-L-rhamnopyranoside, M-207 Methyl 3,4-0-isopropylidene-2-0-methyl-p-D-ribopyranoside, M-209 Methyl 3,4-0 -isopropylidene-2- O -methyl-1 -thio- p-L-fucopyranoside, T-63 Methyl 2,3-0-isopropylidene-5-5-methyl-5-thio-p-D-ribofuranoside, T-91 Methyl 2,3-0 -isopropylidene-6-O-methyl-5-O-tosyl-p-L-allofuranoside, M-148... 

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