Silver-assisted goldcatalysis was applied to alkynyl glycosyl carbonate donors for the synthesis of purine, pyrimidine, quinolin-2-one, and asparagine glycosides. It was demonstrated (40 examples) to be highly versatile for the synthesis of important types of N-glycosides. The method has been utilized for the synthesis of various 2’-modified nucleosides and the disaccharide dipeptide moiety of chloroviruses
Highly β-stereoselective nucleosidation from α-d-xylo- and α-d-ribo-furanose 1,2-thiocarbonates
作者:Rafael Robles、Concepción Rodrı́guez、Luis Álvarez de Cienfuegos、Antonio J. Mota
DOI:10.1016/j.tetasy.2003.12.037
日期:2004.3
Cyclic 1,2-thiocarbonates of alpha-D-xylo- and alpha-D-ribo-furanoses were found to be excellent glycosyl donors in mild NIS-mediated nucleophilic substitution reactions, affording beta-nucleosides with complete stereo selectivity and moderate to high yields after treatment with persilylated pyrimidinic bases. The nucleophile is believed to open the thiocarbonate ring at the anomeric position presumably via an S(N)2 mechanism. Participation of the nucleobase silylating agent [N,O-bis(trimethylsilyl)acetamide] in the mechanism of the nucleosidation step was shown, where a large excess of it has been proven to be necessary in order to achieve high yields. Absolute configurations at C-1' were ascertained by chemical correlation synthesizing the corresponding 2,2'-anhydronucleosides. (C) 2004 Elsevier Ltd. All rights reserved.
Propargyl 1,2-Orthoesters for a Catalytic and Stereoselective Synthesis of Pyrimidine Nucleosides
Pyrimidine nucleosides are synthesized by using propargyl 1,2-orthoesters and Au(III) salt as a catalyst. Strategically positioned 1,2-orthoesters are found to yield only 1,2-trans nucleosides and enable preparation of 2'-OH containing pyrimidine nucleosides. The glycosyl donor employed in this study is stable and easily accessible. The identified high-yielding protocol is mild, diastereoselective, and catalytic.
BENHADDOU, R.;CZERNECKI, S.;VALERY, J. M.;BELLOSTA, V., BULL. SOC. CHIM. FR.,(1991) N, C. 108-111
作者:BENHADDOU, R.、CZERNECKI, S.、VALERY, J. M.、BELLOSTA, V.