Rhamnopyranoside, methyl 2,3-0-isopropylidene

Methyl 2,3-isopropylidene-a-L-rhamnopyranoside was converted into the 4-tosyl derivative (LVII), from which the isopropylidene residue was removed by mild hydrolysis. Methylation then gave methyl 2,3-di-methyl-4-tosyl-a-L-rhamnopyranoside (LVIII), from which the reductive fission of the aromatic residue with sodium amalgam followed by hydrolysis gave 2,3-dimethyl-L-rhamnose (LIX).68 The same product was obtained by the substitution of benzoyl for tosyl, followed by methylation and separation on a column of cellulose.84 In an earlier synthesis,89 2,3-isopropylidene-L-rhamnose was converted into the 1,5-dibenzyl ether (LX) by treatment with benzyl chloride and potassium hydroxide. 

Although the 2,3-dimethyl and 3,4-dimethyl ethers of L-rhamnose were known, the 2,4-dimethyl ether had not been synthesized prior to its preparation through a trifluoroacetyl intermediate. - The synthesis started from methyl 2,3-0-isopropylidene-a-L-rhamnopyranoside this was methylated and the acetal group removed, to give methyl 4-0-methyl-a-L-rhamnopyranoside (6). Conversion to the 2,3-bis(trifluoroacetate) (7) was readily achieved with trifluoroacetic anhydride in the presence of sodium trifluoroacetate. As expected, the trifluoroacetate (7) was completely de-acylated by treatment with alcohol, regenerating (6) this process was complete after 25 min. at room temperature. The procedure for selective de-esterification was based on the observation that, if excess carbon tetrachloride (6 vol.) is present, very little methanolysis occurs. By use of a mixed methanol-carbon tetrachloride solvent (65 35 vol./vol.), the meth-... 

Table IV also includes some values determined in methanol as the solvent these are very much higher (and, hence, also more accurate) than those in water, because the polyol competes with methanol, rather than with water, for outer-sphere positions on the cation. These figures explain why carbohydrates are soluble in methanol or ethanol containing high concentrations of calcium chloride, or even potassium acetate, and in such systems as lithium chloride in 2-methoxyethanol. ° Sugar derivatives that are soluble in non-hydroxylic solvents form complexes with cations in those solvents even more readily for example, methyl 2,3-0-isopropylidene-4-0-methyl-) -L-rhamnopyranoside (24) (but not its a anomer) will form a complex with sodium iodide in acetone, the Na" " ion coordinating to 0-1,0-2, and 0-3. In aqueous solution, the concentration of this complex would be negligible.

Die Spaltung von Methyl-4-O-tosyl-O-isopropyliden-rhamnopyranosid in 80%igem Methanol mit 4% Natriumamalgam (14 Stdn.) liefert Melhyl-O-iospropyliden-rharntiopy-ranosid5 (Kp0.3 84-85°). 

Treatment of the disaccharide allylic mesylate (18) with sodium azide gave the product of 5 2 displacement (19) (30%) and also the rearranged isomer (20) (42%) (Scheme 9). The former, after reduction, gave a disaccharide derivative of purpurosamine. A further report on unsaturated disaccharide derivatives describes the condensation between 1,2 3,4-di-O-isopropylidene-a-D-galactose, 1,2 5,6-di-O-isopropylidene-a-D-glucose, and benzyl and methyl 2,3-0-iso-propylidene-a-L-rhamnopyranoside and the enone (21) brought about by the use of diethyl azodicarboxylate and triphenylphosphine in the presence of mercury(ll) bromide. Enone products were formed as shown (Scheme 10), and... 

Benzyl 2,3-0-isopropylidene-a-D-lyxofuranoside, 1-70 Benzyl 2,3-0-isopropylidene-p-D-lyxofuranoside, L-72 Benzyl 2,3-0-isopropylidene-a-D-mannofuranoside, B-19 Benzyl 2,3-0-isopropylidene-a-D-mannopyranoside, B-19 Benzyl 2,3-0-isopropylidene-5-0-mesyl-a-D-lyxofuranoside, 1-70 Benzyl 2,3-0-isopropylidene-6-0-mesyl-a-D-mannofuranoside, B-19 Benzyl 2,3-0-isopropylidene-4-0-mesyl-a-L-rhamnopyranoside, B-20 Benzyl 3,4-0-isopropylidene-2-C-methyl-p-L-arabinopyranoside, M-229 Benzyl 3,4-0-isopropylidene-2-C-methyl-p-L-ribopyranoside, M-286 Benzyl 3,4-0-isopropylidene-2-0-methyl-p-D-ribopyranoside, B-21 Benzyl 3,4-0-isopropylidene-2-0-methyl-p-L-ribopyranoside, B-21 Benzyl 3,4-0-isopropylidene-p-D- /7// ro-pentopyranosid-2-ulose, P-42 Benzyl 2,3-0-isopropylidene-a-L-rhamnopyranoside, B-20 Benzyl 2,3-0-isopropylidene-p-D-ribofuranuronoside, R-146 Benzyl 3,4-0-isopropylidene-p-D-ribopyranoside, B-21 Benzyl 3,4-0-isopropylidene-p-L-ribopyranoside, B-21 Benzyl 3,4-0-isopropylidene-2-0-(2,3,4,6-tetra-0-acetyl-p-D-glucopyranosyl)-p-D-arabinopyranoside, G-284 Benzyl 2,3-0-isopropylidene-5-0-(2,3,4,6-tetra-0-acetyl-p-D-glucopyranosyl)-p-D-ribofuranoside, G-462 Benzyl 3,4-0-isopropylidene-2-0-tosyl-a-D-arabinopyranoside, B-14 Benzyl 3,4-0-isopropylidene-2-tosyl-p-L-arabinopyranoside, B-14 Benzyl 3,4-0-isopropylidene-2-0-(2,3,5-tri-0-benzoyl-a-L-arabinofuranosyl)-p-L-arabinopyranoside, A-801 Benzyl 3,4-0-isopropylidene-6-0-trityl-p-D-galactopyranoside, B-15... 

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 4-0-acetyl-2,3-0-isopropylidene-a-L-rhamnopyranoside, M-207 Methyl 5-5-acetyI-2,3-0-isopropylidene-5-thio-a-D-lyxofuranoside, T-80 Methyl 5-5-acetyI-2,3-0-isopropylidene-5-thio-a-L-rhamnofuranoside, T-88 Methyl 4-0-acetyI-2,3-0-isopropylidene-l-thio-p-D-xylopyranoside, T-98 Methyl 2-0-acetyI-4,6-0-isopropylidene-3-0-tosyl-a-D-gulopyranoside, M-194... 

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-5-0-mesyl-a-D-rhamnofuranoside, M-206 Methyl 2,3-0-isopropylidene-4-0-mesyl-a-D-rhamnopyranoside, M-207 Methyl 2,3-0-isopropylidene-4-0-mesyl-a-L-rhamnopyranoside, M-207 Methyl 3,5-0-isopropylidene-2-0-mesyl-a-D-xylofuranoside, M-216 Methyl 2,3-0-isopropylidene-6-0-methyl-p-L-dlofuranoside, M-148 Methyl 2,3-0-isopropylidene-3"-methyl-D-apio-p-D-furanoside, A-785 Methyl 3,4-0-isopropylidene-2-0-methyl-p-D-arabinopyranoside, M-153... 

Methyl 3,5-0-isopropylidene-2-O-methyl-a-D-xylofuranoside, M-216 Methyl 3,5-0-isopropylidene-2-O-methyl-p-D-xylofuranoside, M-216 Methyl 2,3-0-isopropylidene-p-D-r 6o-pentodialdo-l,4-furanoside, P-35 Methyl 3,5-0-isopropylidene-p-D-tAreo-pentofuranoside, P-45 Methyl 3,5-0 -isopropylidene-a-D-tAreo -pentofuranosid-2-ulose, P-45 Methyl 3,4-0 -isopropylidene- -i -erythro -pentopyranosid-2-ulose, P-42 Methyl 3,4-0 -isopropylidene-a-L-erytAro -pentopyranosid-2-ulose, P-42 Methyl 3,4-0 -isopropylidene-p-L-erytAro -pentopyranosid-2-ulose, P-42 Methyl 2,3-0 -isopropylidene-p-L-erytAro -pentopyranosid-4-ulose, P-44 Methyl 2,3-0 -isopropylidene-p-DL-erytAro -pentopyranosid-4-ulose, P-44 Methyl 2,3-0-isopropylidene-a-L-rhamnofuranoside, M-206 Methyl 2,3-0-isopropylidene-a-o-rhamnopyranoside, M-207 Methyl 2,3-0-isopropylidene-a-L-rhamnopyranoside, M-207 Methyl 2,3-0-isopropylidene-p-D-ribofuranoside, 1-74 Methyl 2,3-0-isopropylidene-p-L-ribofuranoside, 1-74 Methyl 2,3-0-isopropylidene-5-0-a-D-ribofuranosyl-P-D-ribofuranoside, R-119... 

Methyl 2,3-di-O-acetyl-4-thio-a-L-rhamnopyranoside, T-87 Methyl 2,6-dideoxy-4-thio-a-D-riZ o-hexopyranoside, 9CI, D-656 Methyl 2,3 4,6-di-0-isopropylidene-5-thio-a-L-idopyranoside, T-76 Methyl 2,3 4,6-di-0-isopropylidene-5-thio-p-L-idopyranoside, T-76 Methyl 2,3-di-O-methyl-4-thioglucopyranoside 4,6-cyclic phosphonate a-D-(i )p-/orm i -Chloro, M-177... 

Allyl 3,4-di-O-benzyl-a-D-rhamnopyranoside, A-95 Allyl 2,4-di-O-methyl-a-L-rhamiiopyTanoside, A-95 Allyl 2,3-O-isopropylidene-a-D-rhaninopyrajioside, A-95 Allyl 2,3- 2-isopropylidene-a-L-rhamnopyrajioside, A-95 Allyl 4-O-metliyl-a-L-rhaniiiopyranosid A-95 Allyl rhamnopyranoside a-L-form, A-95 Allyl 2,3,4-tri-O-acetyl-0 -L-rhamnopyranoside, A-95 Allyl 2,3,4-tri-O-benzyl-a-D-rhamnopyranoside, A-95 Allyl 2,3,4-tri-O-metliyl-a-L-rliainnopyranoside, A-95 2-Amino-2-deoxy-a-L-galactopyranuronosyl-(l -> 3)-2-amino-2-deoxy-a-D-quinovosyl-(l 3)-D-rhamnose a-Pyranose-/orm 2W,2 W-Di-Ac, A-205... 

Benzyl 5-0-benzyl-2,3-di-O-metbyl-a-L-rliamnofiiranoside, B-20 Benzyl 2,3-0-exo-benzylidene-a-L-rbamnopyranoside, B-20 Benzyl 2,3-0-eMi/o-benzylidene-a-L-rbamnopyranoside, B-20 Benzyl 5-0-benzyl-2,3-(7-isopropylidene-a-L-rbamnofuranoside, B-20 Benzyl 4-0-benzyl-2,3-0-isopropylidene-a-L-rbamnopyranoside, B-20 Benzyl 4-0-benzyl-2,3-0-isopropylidene-p-L-rbamnopyranoside, B-20 Benzyl 5-0-benzyl-a-L-rhamnofnranoside, B-20 Benzyl 4-6>-benzyl-p-L-rhamnopyranoside 2,3-carbonate, B-20 Benzyl 2-0-benzyl-a-L-rhamnopyranoside, B-20 Benzyl 3-0-benzyl-a-L-rhamnopyranoside, B-20 Benzyl 4-0-benzyl-a-L-rhamnopyranoside, B-20 Benzyl 4-0-benzyl-p-L-rhamnopyranoside, B-20 Benzyl 2,4-di-O-benzyl-a-D-rhamnopyranoside, B-20 Benzyl 3,4-di-O-benzyl-a-D-rhamnopyranoside, B-20 Benzyl 2,4-di-O-benzyl-a-L-rhamnopyranoside, B-20 Benzyl 3,4-di-O-benzyl-a-L-rhamnopyranoside, B-20 Benzyl 2,3-0-isopropylidene-4-0-mesyl-a-L-rliamnopyranoside, B-20 Benzyl 2,3-0-isopropylidene-a-L-rhamnopyranoside, B-20 Benzyl rhamnoside a-L-Pyranose-/< rm, B-20 Benzyl 2,3,4-tri-O-acetyl-a-L-rhamnopyranoside, B-20 6-Deoxy-3,4-di-0-methyl-L-mannose, 9CI, SCI, R-79 6-Deoxy-2,3-di-0-methyl-L-mannose, 9CI, R-79 6-Deoxy-2,4-di- 0 -methyl-L-mannose, R-79 6-Deoxymannonic acid L-form, D-286 6-Deoxy-D-mannono-l, 4-lactone, D-286 6-Deoxy-2-0-methyl-L-mannose, 8CI, R-79 6-Deoxy-3-0-methyl-L-mannose, 9CI, R-79 6-Deoxy-3-C-methylmannose D-form, D-308 6-Deoxy-4-0-methyl-L-mannose, R-79 6-Deoxy-5-0-methyl-L-mannose, R-79 6-Deoxy-2-0-a-L-rhamnopyranosyl-L-talose, D-355 6-Deoxy-2,3,4-tri-0-methyl-L-mannose, 9CI, R-79... 

Ethyl 2-0-benzoyl-1-thio-a-L-rhamnopyranoside, T-86 Ethyl 4-O-benzoyl-l-thio-a-L-rhamnopyranoside, T-86 Ethyl 4-0-benzyi-2-0-methyl-l-thio-a-D-rhamnopyranoside, T-86 Ethyl 4-O-benzyl-l-thio-a-D-rhamnopyranoside, T-86 Ethyl 2,4-di-O-benzoyl-l-thio-a-L-rhamnopyranoside, T-86 Ethyl 2,3-O-isopropylidene-l-thio-a-D-rhamnopyranoside, T-86 Ethyl rhamnoside a-L-Furanose-/orm, E-27 Ethyl I-thicHX-L-rhamnopyranoside, T-86 Ethyl I-thio-p-L-rhamnopyranoside, T-86 Ethyl 2,3,4-tri-O-acetyl-l-thio-a-L-rhamnopyranoside, T-86 Ethyl 2,3,4-tri-0-acetyl-l-thio-(3-L-rhamnopyranoside, T-86 a-D-Fucopyranosyl-(l ->2)-a-L-rhamnopyranosyl-(l ->3)-i>mannose, F-159... 

Two polymorphs of a,a-trehalose octacetate monohydrate, 4,4 -dideoxy-a,a- ty/o-trehalose, methyl 2,3,4,6,2, 4, 6 -hepta-C -acetyl-a-laminaribinoside, 2 3,3 -dideoxy-a,a-flrflbjno-trehalosc. 3 Methyl 2,3-0-isopropylidene-5-0-tosyl-P-D-ribofuranoside 2, the 7-carbon glycoside 3 (see Chapter 17), C-glycosidic furanoside 4 (see Chapter 14) the oxazoline derivative 5 and methyl 1,6-di-0-(4-bromobenzoyl)-3,4-di-0-(4-methoxycinnamoyl)-P-D-fructofuranoside. Di-(3-deoxy-D-g/yccro-pcntulose)-l,2 2,r-dianhydridc, methyl 4,6-benzylidene-a-D-allopyranoside, methyl-2,3,4-tri-0-acctyl-a-L-rhamnopyranoside, l 2-(indol-3-yl)ethyl 2,3,4-tri-O-acetyl-a-L-... 

Photolysis of solutions of acetic and pivalic esters in aqueous HMPT also resulted in deoxygenation for example, photolysis (A 254 nm) of methyl 4-0-acetyl-2,3-0-isopropylidene-a-L-rhamnopyranoside and 1,2 5,6-di-0-isopropylidene-3-0-pivaloyl-a-D-glucofuranose gave the corresponding 4- and 3-deoxy derivatives, respectively, in yields of 70 and 75 The method was also extended to hexoses... 

The 2,3-0-hexafluoroisopropylidene acetal 10 was formed almost quantitatively on treatment of methyl a-L-rhamnopyranoside with hexafluoroacetone in the presence of DCC, and the mixed diacetal 11 was similarly obtained from 1,2-0-isopropylidene-a-D-glucofuranose, although in moderate yield only. Compound 11 was selectively hydrolysed to the monoacetal 12, since hexafluoroacetonide groups are more stable towards acid than non-fluorinated ones."... 

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