- Slow glycosylation: Activation of trichloroacetimidates under mild conditions using lithium salts and the role of counterions
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Glycosylations were carried out with the two glycosyl donors 4-O-acetyl-2,3-O-isopropylidene-1-O-trichloroacetimidoyl-α-L-rhamnopyranose and 2,3,4-tri-O-benzyl-1-O-trichloro-acetimidoyl-α-L-rhamnopyranose in combination with the two alcohols 1-adamantanol and L-menthol as model glycosyl acceptors. As catalysts, the five lithium salts LiNTf2, LiI, LiClO4, LiPF6 and LiOTf were investigated. We demonstrated that both lithium and the respective counterions are playing a role in the activation of trichloroacetimidate glycosyl donors at rt. Under these very mild conditions, the glycosylations are slow and completed in two to eight days. Depending on the counterion, the rate and yield of the reaction differs; however, the selectivity of all investigated lithium salts is deficient.
- Korber, Nora Katharina,Pedersen, Christian Marcus
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supporting information
(2022/01/19)
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- Direct one-pot conversion of acylated carbohydrates into their alkylated derivatives under heterogeneous reaction conditions using solid NaOH and a phase transfer catalyst
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A convenient one-pot protocol for the direct conversion of acyl-protected carbohydrates into their alkylated counterparts has been developed by using alkyl halides in the presence of solid sodium hydroxide and a phase transfer catalyst. These economically
- Madhusudan, Soni Kamlesh,Agnihotri, Geetanjali,Negi, Devendra S.,Misra, Anup Kumar
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p. 1373 - 1377
(2007/10/03)
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- Total synthesis of calonyctin A2, a macrolidic glycolipid with plant growth-promoting activity
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Calonyctin A2, a tetrasaccharidic glycolipid having a 22-membered macrolidic structure, has been synthesized by the assembly of three 6- deoxygenated thioglycoside intermediates. The short-step synthesis was achieved by preparation of the most complicated
- Furukawa, Jun-Ichi,Kobayashi, Shigeru,Nomizu, Motoyoshi,Nishi, Norio,Sakairi, Nobuo
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p. 3453 - 3457
(2007/10/03)
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