Formation of Some Oxygen-Containing Heterocycles by Radical Cyclization: The Stereochemical Influence of Anomeric Effects
摘要:
The influence of the anomeric effect on radical cyclization has been examined by determining the stereochemical outcome of the ring closure of 10 suitably substituted radicals. The stereochemistry of the products formed from the acyclic precursors 4a-f indicates that for suitably constituted radicals anomeric interactions stabilize pseudoaxially substituted transition structures 14 thus affording products with stereochemistry the reverse of that normally observed.
Formation of Some Oxygen-Containing Heterocycles by Radical Cyclization: The Stereochemical Influence of Anomeric Effects
作者:Athelstan L. J. Beckwith、Dennis M. Page
DOI:10.1021/jo980359u
日期:1998.7.1
The influence of the anomeric effect on radical cyclization has been examined by determining the stereochemical outcome of the ring closure of 10 suitably substituted radicals. The stereochemistry of the products formed from the acyclic precursors 4a-f indicates that for suitably constituted radicals anomeric interactions stabilize pseudoaxially substituted transition structures 14 thus affording products with stereochemistry the reverse of that normally observed.
Diastereocontrol by Trialkylaluminums in the Synthesis of Tetrahydrofurans via Radical Cyclization
作者:Cecilia Ericsson、Lars Engman
DOI:10.1021/ol016429s
日期:2001.11.1
[reaction: see text]. The influence of various Lewis acids in the radical cyclization of beta-allyloxyalkyl phenyl selenides was investigated. Whereas the unperturbed cyclization afforded trans-2,4-disubstituted tetrahydrofurans as the major products (cis/trans approximately 1/4.5), cyclization in the presence of trialkylaluminums (3 equiv) afforded predominantly (cis/trans approximately 7/1) the corresponding