- EFFECT OF PROTECTING GROUPS AND SOLVENTS IN ANOMERIC O-ALKYLATION OF MANNOPYRANOSE
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Anomeric O-alkylation of mannopyranoses with various protecting groups was investigated using mannose derivatives and 2,3-O-isopropylidene-1-O-trifluoromethanesulfonyl-D-glycerol (1) as alkylating agent.Generally, in polar solvents higher α/β ratios were obtained than in nonpolar solvents.Sterically demanding protecting groups at the 6-O-position and polar solvents led to higher yields.Reactivity differences were explained by different complex formation.Based on these results mannopyranosyl-α(1-4)glucopyranosides 26 and 27 were synthesized using mannose derivatives 5 and 6 having a 6-O-(p-methoxyphenyl)diphenylmethyl group and galactosyl trifluoromethanesulfonate 24 or nonafluorobutanesulfonate (nonaflate) 25, respectively, as alkylating agents.
- Tamura, Junichi,Schmidt, R. R.
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p. 895 - 912
(2007/10/02)
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- Anomeric O-Alkylation, 9. Disaccharide Synthesis via Anomeric O-Alkylation
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Base-promoted reaction of tetra-O-benzyl-glucose 1a with secondary alkyl trifluoromethanesulfonates 2 and 3 in toluene provides in the presence of 15-crown-5 preferentially β-glycosides 2aβ and 3aβ, respectively, in high yields.For reactions carried out a
- Tsvetkov, Yury E.,Klotz, Wolfgang,Schmidt, Richard R.
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p. 371 - 376
(2007/10/02)
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- TOTAL SYNTHESIS OF CYCLOMALTOHEXAOSE
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Described for the first time is a total synthesis of cyclomaltohexaose, in 0.3percent overall yield, in 21 steps starting from maltose.Maltose was transformed into allyl O-(2,3,6-tri-O-benzyl-α-D-glucopyranosyl)-(1->4)-2,3,6-tri-O-benzyl-β-D-glucopyranosi
- Takahashi, Yukio,Ogawa, Tomoya
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p. 277 - 296
(2007/10/02)
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