Selective activation of “armed’ and ‘'disarmed” glycaldonors enabling the stereo-controlled glycosylations by employing Cu(II)-catalyst as the promoter has been realized. The distinctive stereochemical outcome in the process is mainly influenced by the presence of diverse protecting groups on the donor and the solvent system employed. The protocol is compatible with a variety of aglycones including
Niobium(V) chloride catalyzed microwave assisted synthesis of 2,3-unsaturated O-glycosides by the Ferrier reaction
作者:Srinivas Hotha、Ashish Tripathi
DOI:10.1016/j.tetlet.2005.05.015
日期:2005.7
NbCl5 catalyzes the Ferrier reaction of per-O-acetylated glycals with primary, secondary, allylic, benzylic and monosaccharide alcohols to give 2,3-unsaturated α-glycosides in short reaction times under microwave irradiation conditions.
Scope of AuCl3 in the activation of per-O-acetylglycals
作者:Rengarajan Balamurugan、Srinivasa Rao Koppolu
DOI:10.1016/j.tet.2009.07.087
日期:2009.9
Gold(III)chloride in catalytic amounts activates 3,4,6-tri-O-acetyl-D-glucal, 3,4,6-tri-O-acetyl-D-galactal, and 3,4-di-O-acetyl-L-rhamnal efficiently. The activated species can be employed in the Ferrier reaction with different nucleophiles at ambient conditions. Attempts have been made to make beta-anomer of the Ferrier product from anomeric-O-propargylated Ferrier product. (C) 2009 Elsevier Ltd. All rights reserved.