Chemistry is an experimental science, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 10343-06-3, Name is 2,3,4,6-Tetra-o-acetyl-D-glucopyranose, name: 2,3,4,6-Tetra-o-acetyl-D-glucopyranose.
Glycosyl Imidates, 12. – Direct Synthesis of O-alpha- and O-beta-Glycosyl Imidates
1-O-Unsubstituted aldoses afford with halogen-activated nitriles under base catalysis directly O-alpha- and O-beta-glycosyl imidates which can be isolated as stable compounds.Investigations with 2,3,4,6-tetra-O-benzyl- and -acetylglucose (1a, b), trichloroacetonitrile and trifluoroacetonitrile and NaH and K2CO3, respectively, as base have demonstrated, that the beta-glucopyranosyl-1-oxido oxygen atom is more nucleophilic (rapid formation of 3a-beta, 3b-beta, 4a-beta, and 4b-beta) than the alpha-glycopyranosyl-1-oxido oxygen atom.Because of the reversibility of these reactions, however,due to the anomeric effect finally the thermodynamically more stable alpha-imidates 3a-alpha, 3b-alpha, 4a-alpha, and 4b-alpha are formed exclusively.Therefore O-alpha- and O-beta-glycosyl imidate formation can be conducted highly diastereoselectively. – From trichloroacetonitrile and other 1-O-unsubstituted carbohydrates the imidates 7-alpha – 13-beta were obtained as stable compounds. – Less activated nitriles (chloroacetonitrile, dichloroacetonitrile) have proven not or not so successful in the direct O-glycosyl imidate formation. – N-Aryl ketenimines yielded cleanly base-catalyzed direct O-glycosyl imidate formation.However, because of the irreversibility of this reaction under the reaction conditions only kinetic product formation was observed (leading to the beta-imidates 14a-beta – 14d-beta and 15d-beta.Similarly 1-O-unprotected mannose gave only the beta-product 16d-beta.
Balanced chemical reaction does not necessarily reveal either the individual elementary reactions by which a reaction occurs or its rate law.name: 2,3,4,6-Tetra-o-acetyl-D-glucopyranose. In my other articles, you can also check out more blogs about 10343-06-3
Reference£º
Tetrahydropyran – Wikipedia,
Tetrahydropyran – an overview | ScienceDirect Topics