Rule of Five Cyclizations in and 5-Hexenyl Radicals and Photocyclizations of 1,5-Hexadienes: Effect of 4-Oxa Substitution

Abstract

The effect of 4-oxa substitution on the regiochemistry and rate of 5-hexenyl radical cyclizations was investigated, as a potential model for [2 + 2] photocycloadditions of 2-acyl-4-oxa-1,5-hexadienes. Increasing the electron density in the alkene decreases the rate of cyclization in the 4-oxa-hexenyl radicals, relative to the all carbon analogs, but has little effect on the regioselectivity of the cyclization. The radical model does not reproduce the high degree of 1,6 closure, observed in the [2 + 2] photocycloadditions for 4-oxa-1,5-hexadiene 1a. However, the radical model does reinforce the interpretation that ground state conformational effects, engendered by substitution remote from the reacting centers have important rate consequences for cyclization reactions. Copyright © 2007 John Wiley & Sons, Ltd.

Publisher

Wiley

Publication Date

1-1-2007

Publication Title

Journal of Physical Organic Chemistry

Department

Chemistry and Biochemistry

Document Type

Article

DOI

https://dx.doi.org/10.1002/poc.1120

Language

English

Format

text

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