Synthesis of difluorinated carbocyclic analogues of 5-deoxypentofuranoses and 1-amino-5-deoxypentofuranoses: en route to fluorinated carbanucleosides
作者:Gaëlle Fourrière、Nathalie Van Hijfte、Jérôme Lalot、Guy Dutech、Bruno Fragnet、Gaël Coadou、Jean-Charles Quirion、Eric Leclerc
DOI:10.1016/j.tet.2010.03.079
日期:2010.5
The synthesis of difluorinated carbocyclic analogues of 5-deoxypentofuranoses and 1-amino-5-deoxypentofuranoses is described. The sequence involves an addition of PhSeCF2TMS to carbohydrate-derived aldehydes or their corresponding tert-butanesulfinylimines followed by a radical cyclization. Optimized conditions for the PhSeCF2TMS addition to alpha-chiral aldehydes have been disclosed and its unusual diastereoselectivity is discussed. Application of the sequence using Ellman's auxiliary allows a more direct access to 1-aminopentose analogues with a complete control of the pseudo-anomeric center configuration. (C) 2010 Elsevier Ltd. All rights reserved.
Convenient strategy for the synthesis of highly functionalizable hydroxylated unsaturated azepanes
A convenient approach to the construction of dihydroxylated unsaturated azepanes featuring a functional group (ethoxycarbonyl)methyl or (cyano)methyl at C-2 was achieved from a pent-4-enal synthon obtained in four steps from D-xylose. The key step of the sequence relied on the conjugate addition of allylamine to alpha,beta-unsaturated ester or nitrile, prepared by Wadsworth-Emmons olefination. Subsequent RCM afforded the target unsaturated azepanes. (C) 2012 Elsevier Ltd. All rights reserved.