Stereoselection in 5-exo radical cyclizations of polysubstituted 2-oxahex-5-enyl radicals:: A systematic study of the combination substituent effect

被引：23

作者：

Wille, U ^{[1
]}

Lietzau, L ^{[1
]}

机构：

[1] Univ Kiel, Inst Organ Chem, D-24098 Kiel, Germany

来源：

TETRAHEDRON | 1999年 / 55卷 / 38期

关键词：

radicals and radical reactions; diastereoselection; transition states; cyclization;

D O I：

10.1016/S0040-4020(99)00663-8

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

The nitrate radical induced oxidative cyclization of the alkynyl ethers cis/trans-1-3 proceeds with high diastereroselectivity and leads to the annellated tetrahydrofurans cis/trans-13-15. The stereoselectivity in this reaction sequence is likely determined in the 5-exo radical cyclization step of the intermediate polysubstituted 2-oxahex-5-enyl radicals cis/trans-7-9. The respective transition state geometries of these cyclizations are discussed within the framework of the Beckwith-Houk model. A dependence of the stereoselection on the configuration and size of the fused cycloalkyl ring as well as on the stability of the 2-oxahex-5-enyl radicals cis/trans-7-9 is observed. (C) 1999 Elsevier Science Ltd. All rights reserved.

引用

页码：11465 / 11474

页数：10

共 11 条

[1] THIAZOLIDINE DERIVATIVES - A NEW SOURCE OF ALPHA-AMINOALKYL RADICALS FOR CARBON-CARBON BOND FORMATION IN SYNTHESIS [J].