with exclusive regioselectivity and stereoselectivity. Functional application of such a resultant product by oxidative addition and epoxidation is also explored. Notably, the treatment of a pyrroline-fused N-glycoside (3a) with TMSOTf efficiently leads to an interesting unexpected C-nucleoside (9) via a TMSOTf-inducing ring opening/acetyl migration/ringclosingreaction sequence.
Highly Stereoselective Synthesis of 2,3-Unsaturated Thioglycopyranosides Employing Molecular Iodine
作者:Basi Reddy、Ch. Divyavani、Jhillu Yadav
DOI:10.1055/s-0029-1218722
日期:2010.5
Molecular iodine has been utilized for the first time for the thioglycosidation of d-glycals with various thiols to afford the corresponding 2,3-unsaturated thioglycosides in high yields. In the case of tri-O-acetyl-d-glucal, the α-anomer was obtained exclusively. The use of readily available iodine makes this method quite simple, more convenient, and practical.
InBr3-Catalyzed Ferrier Rearrangement: An Efficient Synthesis of C-Pseudoglycals
作者:J. S. Yadav、B. V. Subba Reddy
DOI:10.1055/s-2002-20968
日期:——
Glycals react smoothly with silyl nucleophiles such as allyltrimethylsilane, trimethylsilyl cyanide and trimethylsilyl azide in the presence of a catalytic amount of indium tribromide to give the corresponding 2,3-unsaturated allyl glycosides, glycosyl cyanides and glycosyl azides in excellent yields with high α-selectivity.
Generation of Nitrile Oxides under Nanometer Micelles Built in Neutral Aqueous Media: Synthesis of Novel Glycal-Based Chiral Synthons and Optically Pure 2,8-Dioxabicyclo[4.4.0]decene Core
作者:Nirbhik Chatterjee、Palash Pandit、Samiran Halder、Amarendra Patra、Dilip K. Maiti
DOI:10.1021/jo801337k
日期:2008.10.3
for chemoselective oxidation of aldoximes to nitrile oxides by iodosobenzene in neutral aqueousmedia is reported. Their in situ intermolecular 1,3-dipolar cycloaddition (1,3-DC) with olefins in nanometer aqueous micelles occurs with improved stereoselectivity and acceleration of reactionrate toward synthesis of new chiral synthons, 3-(2'-C-3',4',6'-tri-O-benzylglycal)-Delta(2)-isoxazolines and others
cascade amidoglycosylation was initiated by a benzenesulfonimide radical generated from NFSI under the catalytic reduction of TEMPO. The benzenesulfonimide radical was electrophilically added to the glycals, and then the resulting glycosidic radical was converted to oxocarbenium upon oxidation by TEMPO+, which enabled the following anomeric specific glycosylation.
建立了一种以氮为中心的自由基介导的一步制备1,2-反式-2-氨基-2-脱氧糖苷的策略。级联酰胺糖基化由 NFSI 在 TEMPO 催化还原下产生的苯磺酰亚胺自由基引发。苯磺酰亚胺自由基亲电加成到糖基上,然后得到的糖苷自由基在被 TEMPO +氧化后转化为氧代碳鎓,这使得以下异头特异性糖基化成为可能。