Ring-Contraction vs Ring-Expansion Reactions of Spiro-cyclopropanecarboxylated Sugars
摘要:
Electrophilic ring opening of spiro-cyclopropanecarboxylated sugars followed by reaction with DBU revealed interesting ring-contraction and ring-expansion reactions depending on the substrate and the kind of hydroxyl protective group present adjacent to the Spiro center. A stereoselective method for accessing a new class of carbon chain extended keto-furanoses and C-glycosylated bicyclic compounds is reported.
A New Method for the Stereoselective Synthesis of α- and β-Glycosylamines Using the Burgess Reagent
作者:K. C. Nicolaou、Scott A. Snyder、Annie Z. Nalbandian、Deborah A. Longbottom
DOI:10.1021/ja049293c
日期:2004.5.1
Although glycosylamines constitute an important group of carbohydrates from the standpoint of biology and medicine, methods for their synthesis typically lack substrate generality and/or result in variable stereoselectivity, especially in complex contexts. In this communication, we report an operationally simple method for the synthesis of both α- and β-glycosylamines using the Burgessreagent that overcomes