92052-30-7Relevant academic research and scientific papers
Allyl, epoxy and glycosyl perfluoroimidates. One-pot preparation and reaction
Nakajima, Noriyuki,Saito, Miho,Kudo, Masabumi,Ubukata, Makoto
, p. 3579 - 3588 (2002)
The one-pot preparation of allyl, epoxy and glycosyl perfluoroimidates and their reaction are described. Volatile perfluoronitriles were generated from perfluoroamides with an 'activated' dimethyl sulfoxide (DMSO) species at -78°C. Allyl, epoxy and glycosyl perfluoroimidates were prepared in 44-92% yield following in situ nucleophilic addition of alcohol and sugar derivatives to nitriles. The obtained trifluoroacetimidates were more stable than the trichloro analogue and were easily purified by SiO2 column chromatography and/or distillation. The 3,3-sigmatropic rearrangement of allylic analogues, acid-catalyzed cyclization of the epoxy analogues and glycosylation of sugar analogues were studied comparing with their corresponding trichloroacetimidates. The trifluoroacetimidates were considerably less reactive than trichloroacetimidates due to their electron-withdrawing substituents on the imidate carbon.
Glycosyl Imidates, 12. - Direct Synthesis of O-α- and O-β-Glycosyl Imidates
Schmidt, Richard R.,Michel, Josef,Roos, Michael
, p. 1343 - 1357 (2007/10/02)
1-O-Unsubstituted aldoses afford with halogen-activated nitriles under base catalysis directly O-α- and O-β-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 β-glucopyranosyl-1-oxido oxygen atom is more nucleophilic (rapid formation of 3a-β, 3b-β, 4a-β, and 4b-β) than the α-glycopyranosyl-1-oxido oxygen atom.Because of the reversibility of these reactions, however,due to the anomeric effect finally the thermodynamically more stable α-imidates 3a-α, 3b-α, 4a-α, and 4b-α are formed exclusively.Therefore O-α- and O-β-glycosyl imidate formation can be conducted highly diastereoselectively. - From trichloroacetonitrile and other 1-O-unsubstituted carbohydrates the imidates 7-α - 13-β 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 β-imidates 14a-β - 14d-β and 15d-β.Similarly 1-O-unprotected mannose gave only the β-product 16d-β.
