这项工作得到了德国科学与创新部长的 Gobierno de Canarias 研究计划 (SolSubC200801000192 和 CTQ2010-18244) 的支持,并由 Fondo Europeo de Desarrollo 地区 (FEDER) 共同资助。IP-M。感谢西班牙部长级 Ciencia e Innovacion 的研究计划 PIE 200930I138。LMQ 感谢 Consejo Superior de Investigaciones Cientificas (CSIC)(I3P 计划)提供的奖学金。
Hydrogen Atom Transfer Experiments Provide Chemical Evidence for the Conformational Differences between C- and O-Disaccharides
作者:Elisa I. León、Angeles Martín、Inés Peréz-Martín、Luis M. Quintanal、Ernesto Suárez
DOI:10.1002/ejoc.201000470
日期:2010.9
promoted by alkoxyl radicals generated from 3-hydroxypropyl α- d -mannopyranoside derivative ( O -glycoside) and 2,6-anhydro- d - glycero - d - manno -decitol derivative ( C -glycoside) is studied. The O -glycoside model abstracts preferentially the hydrogen atom at C-5 (1,8-HAT) while the C -glycoside abstracts the hydrogen atom at C-1 (1,6-HAT) but no abstraction at C-5 could be detected. These results
Cycloaddition of a chiral nitrone to allylic motifs: an access to enantiopure sugar-based amino acids displaying a stable glycosidic bond and to 4(S)-4-hydroxy-l-ornithine
作者:Kaïss Aouadi、Moncef Msaddek、Jean-Pierre Praly
DOI:10.1016/j.tet.2011.12.048
日期:2012.2
A (-)-menthone-derived nitrone and various allyl O-, and S-glycosides reacted at 110 degrees C to afford the corresponding cycloadducts in good yields. For an N-acetylated allyl N-glycoside, an N-glycoside-based product was formed in poor yield with loss of the N-acetyl residue, while the major product 4 (60%), in which the sugar moiety was absent, arose from cleavage of the N-glycosidic bond, under the cyclo-addition conditions. The cycloadducts of the O-, and S-glycoside type were ring-opened and subjected to acidic and basic hydrolysis, for removing the chiral auxiliary. This resulted in glycosidic bond cleavage for O-glycosides and loss of material, while an S-glycoside amino acid was isolated in 78% yield, indicating a higher resistance of the S-glycosidic bond. N-O Bond cleavage and hydrolytic treatments applied to 4 afforded 4(S)-4-hydroxy-L-ornithine in high yield. Use of the nitrone derived from (+)-menthone should afford the enantiomer of 4, both precursors of 4-hydroxy arginine derivatives by guanidination. (C) 2011 Elsevier Ltd. All rights reserved.