Neighboring-Group Participation by C-2 Ether Functions in Glycosylations Directed by Nitrile Solvents
作者:Chin-Sheng Chao、Ching-Yu Lin、Shaheen Mulani、Wei-Cheng Hung、Kwok-kong Tony Mong
DOI:10.1002/chem.201100732
日期:2011.10.17
Ether‐protecting functions at C‐2 hydroxy groups have been found to play participating roles in glycosylations when the reactions are conducted in nitrile solvent mixtures. The participation mechanism is based on intramolecular interaction between the lone electron pair of the oxygen atom of the C‐2 ether function and the nitrile molecule when they are positioned in a cis configuration. A 1,2‐cis glycosyl
The preparation of 2-iodoamides from glucals and their further transformations into oxazolines
作者:Michael De Castro、Cecilia H. Marzabadi
DOI:10.1016/j.tetlet.2004.06.082
日期:2004.8
2-Deoxy-2-iodo-glycosylamides have been prepared from a variety of protected D-glucals by their reaction with N-iodo-succinimide and amides. Benzyl protected 2-iodoamides, when treated with sodium hydride and 15-crown-5, gave stable C1 N-linked 2-glycooxazolines as the major products. Silyl protected 2-iodoamides afforded the C1 C-linked 2-glycooxazolines; presumably by the rearrangement of unstable N-acylaziridine intermediates. (C) 2004 Elsevier Ltd. All rights reserved.
Synthesis and Biological Evaluation of a Backbone-Modified Phytoalexin Elicitor
作者:C. M. Timmers、J. J. Turner、C. M. Ward、G. A. van der Marel、M. L. C. E. Kouwijzer、P. D. J. Grootenhuis、J. H. van Boom
DOI:10.1002/chem.19970030614
日期:1997.6
AbstractTwo suitably protected building blocks (11 and 33) for the preparation of amide‐linked heptaglucoside mimetic 2, an analogue of the naturally occurring phytoalexin elicitor 1a, were readily accessible by glycal chemistry. Sequential elongation of terminal glucuronide 21 with laminaribiosyl hemiaminal 33 and anomeric amine 11 by EDC/HOBt‐catalyzed condensation and two‐step conversion of the C6‐OTr moiety into the corresponding carboxylate function afforded homogeneous carbopeptoid 2 in high overall yield. It was found that replacement of the acetal linkages by the more rigid amide bonds destroys the phytoalexin‐elicitor activity.
GORDON, DANA M.;DANISHEFSKY, SAMUEL J., J. ORG. CHEM., 56,(1991) N1, C. 3713-3715