Palladium-Catalyzed Stereoselective<i>C</i>-Glycosylation of Glycals with Sodium Arylsulfinates
作者:Jimei Ma、Shaohua Xiang、Hong Jiang、Xue-Wei Liu
DOI:10.1002/ejoc.201403550
日期:2015.2
An efficient glycosylation method to synthesize 2-deoxy-C-aryl glycosides was developed. This C-glycosylation strategy is based on a palladium-catalyzeddesulfitative Ferrier-type coupling reaction of glycals and sodiumarylsulfinates. A series of C-aryl glycosides were obtained in moderate to good yields with exclusive regio- and stereoselectivities. The anomeric selectivity was found to depend on
The palladium-catalyzed stereoselective synthesis of 2,3-deoxy-C-aryl glycosides was investigated. The strategy is based on the Pd-catalyzed desulfitative Heck coupling of arylsulfonyl chlorides and glycals with good leaving groups. An attempt was made to establish the reaction mechanism, which may involve PdII/Pd0 interconversion under basic conditions.
Palladium(II) Acetate Catalyzed Stereoselective <i>C</i>-Glycosidation of Peracetylated Glycals with Arylboronic Acids
作者:Jailall Ramnauth、Odile Poulin、Suman Rakhit、Shawn P. Maddaford
DOI:10.1021/ol010070q
日期:2001.6.1
[reaction: see text] Addition of a variety of arylboronicacids to peracetylated glycals takes place in the presence of a catalytic amount of Pd(OAc)(2). The reaction involves the syn addition of a sigma-aryl-Pd complex to the glycal double bond followed by anti elimination of Pd(OAc)(2) to provide a carbon-Ferrier type product. This method provides a practical and convenient stereoselective synthesis
diethylzinc and diphenylzinc in the presence of CF3COOH gave the corresponding alky and aryl C-pyranosides via a Ferrierrearrangement in excellent yields. Use of the organozinc species, CF3CO2ZnPh, reacted with high stereoselectivity to give the phenyl C-glycosides. Arylzinc chlorides could also be successfully applied to this reaction in the presence of BF3.OEt2.
2,3-Unsaturated-C-aryl glycopyranosides are important intermediates in the synthesis of medicinally important C-aryl glycosides. Treatment of glycal acetates with triarylindiums in ether at room temperature gives good yields of C-aryl-Delta(2,3)-glycosides of predominantly alpha-configuration. The mechanism of this reaction likely involves the formation of an oxocarbenium ion intermediate via indium(III) Lewis acid-assisted ionization of the glycal C.3 acetate. Coupling of trivinyl- and tris(alkynyl)indiums with glycals similarly led to C-vinyl- and Galkynyl-Delta(2,3)-glycosides in good yield. (C) 2004 Elsevier Ltd. All rights reserved.