Syntheses of Medium-Sized Cyclic Ethers from Carbohydrates via an Intramolecular Nitrile Oxide-Alkene Cycloaddition Strategy
作者:Tony Shing、Yong-Li Zhong
DOI:10.1055/s-2006-939072
日期:——
The regioselectivity of intramolecular 1,3-dipolar cyclo-additions of nitrile oxides prepared from 3-O-alkenyl-l,2-O-isopropylidene-a-D-pentodialdofuranoses is dependent on the length of the alkenyl chain. 3-O-Homoallyl nitrile oxide afforded exo-cyclization oxepane exclusively. 3-O-Pentenyl nitrile oxide produced a mixture of exo- and endo-cyclization adducts (oxocane and oxonane) whereas 3-O-hexenyl