Desulfonylation with Mg−MeOH−NiBr2: An Expedient Reagent System for the Synthesis of 2-Amino-2,3-dideoxy Furanosides
摘要:
A catalytic amount of NiBr2 with Mg-MeOH increases the efficiency of reductive desulfonylation of the beta-sulfonylated aminosugars. The Mg-MeOH-NiBr2 system has been utilized in the synthesis of 2-amino-2,3-dideoxypentofuranosides and 2-amino-2,3-dideoxyhexofuranosides. The yield of the desulfonylation improved dramatically from 0% with the known reagents to 44-75% with Mg-MeOH-NiBr2.
Unusual addition of amines to C-2 of vinyl sulfone-modified-β-d-pent-2-enofuranosyl carbohydrates: synthesis of a new class of β-anomeric 2-amino-2,3-dideoxy-d-threo-pentofuranosides
摘要:
When 3-C-sulfonyl-pent-2-enofuranosides and 3-C-sulfonyl-hex-2-enofuranosides were reacted with primary and secondary amines, only the beta-anomeric methoxy group of the pent-2-enofuranoside did not cause any hindrance to incoming nitrogen nucleophiles. This resulted in the 'unusual' addition of amines, in which the diastereoselectivity of the reaction was overwhelmingly in favor of amino sugars of the D-arabino configuration. Selected products were desulfonylated to obtain a new class of beta-anomeric 2-amino-2,3-dideoxy-D-threo-pentofuranosides. (C) 2008 Elsevier Ltd. All rights reserved.