Chemoselective 1-ethylpiperidine hypophosphite (EPHP)-mediated intermolecular radical additions of 1-deoxy-1-halo-1-iodo-alditols to electron-deficient olefins
摘要:
The chernoselective radical reduction of the iodine atom in a series of 1-deoxy-1-halo-1-iodo-alditols with the 1-ethylpiperidine hypophosphite (EPHP)/AIBN system is described. EPHP is also a good chain carrier for the radical addition of gem-dihalocompounds to electron-deficient olefins. Thus, the synthesis of 4-halo-glycooctononitriles and 4-halo-glycoheptononitriles can be achieved by an intermolecular addition of the 1-deoxy-1-halo-alditol-1-yl radical intermediate to acrylonitrile. (c) 2006 Elsevier Ltd. All rights reserved.
Fragmentation of Carbohydrate Anomeric Alkoxy Radicals: A New Synthesis of Chiral 1-Halo-1-iodo Alditols
作者:Concepción C. González、Alan R. Kennedy、Elisa I. León、Concepción Riesco-Fagundo、Ernesto Suárez
DOI:10.1002/chem.200305294
日期:2003.12.5
reaction was achieved by radicalfragmentation of the C1bond;C2 bond, triggered by the initially formed anomeric alkoxy radical, and subsequent trapping of the C2-radical by iodine atoms. This methodology is compatible with the stability of the protective groups most frequently used in carbohydrate chemistry. The potential utility of these 1-halo-1-iodo alditols as chiral synthons was evaluated by
Chromium(II) chloride-promoted reductive β-elimination of 1,1-dihalo alditols. Synthesis of highly functionalized alk-1-enyl halides
作者:Elisa I. León、Nieves R. Paz、Concepción Riesco-Fagundo、Ernesto Suárez
DOI:10.1016/j.tet.2008.08.100
日期:2008.11
A new general synthetic route to obtain highly functionalized (Z)- and (E)-alk-1-enyl halides is described, where the halogen can be indistinctly F, Cl, Br, and I. The procedure involves CrCl2-promoted reductive elimination of β-O-substituted gem-dihalo alditols easily accessible from carbohydrates. The simplicity and mildness of the reaction conditions and their compatibility with different functional