REACTIONS OF IRON(III) PORPHYRINS WITH OXIDANTS - STRUCTURE-REACTIVITY STUDIES

被引:144
作者
TRAYLOR, TG [1 ]
KIM, C [1 ]
RICHARDS, JL [1 ]
XU, F [1 ]
PERRIN, CL [1 ]
机构
[1] UNIV CALIF SAN DIEGO,DEPT CHEM 0358,LA JOLLA,CA 92093
关键词
D O I
10.1021/ja00117a015
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Electronegatively substituted iron(III) porphyrin chlorides such as tetrakis(pentafluorophenyl)porphyrin react with iodosylbenzenes, peracids, hydroperoxides, and hydrogen peroxide in hydroxylic solvents to form a high-valent oxene that is capable of carrying out further oxidations. According to the yields and stereochemistry of epoxidations, the oxene is formed exclusively via a heterolytic mechanism. Structure-reactivity studies show evidence for continual changes in transition-state structure rather than a change of mechanism from heterolysis with peracids to homolysis with hydroperoxides, as had previously been proposed. These changes can be described by the coefficients partial derivative rho/partial derivative pK(a) or partial derivative beta(1g)/partial derivative sigma and partial derivative beta(1g)/partial derivative pK(a). The observed partial derivative rho/partial derivative pK(a) or partial derivative beta(1g)/partial derivative sigma, as well as the increase in beta(1g) with increasing pK(a)(ROH), can be interpreted with a reaction-coordinate diagram in which both catalyst and oxidant are varied. On the basis of the heterolytic mechanism, a method for efficient, catalytic, and stereoselective epoxidation using simple and inexpensive hydroperoxides has been developed.
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页码:3468 / 3474
页数:7
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