Premium
Rule of five cyclizations in 5‐hexenyl radicals and photocycloadditions of 1,5‐hexadienes: effect of 4‐oxa substitution
Author(s) -
Matlin Albert R.,
Brinton Karen Feit,
Nivaggioli Belinda Tsao
Publication year - 2007
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1120
Subject(s) - chemistry , regioselectivity , radical , alkene , substitution (logic) , medicinal chemistry , computational chemistry , organic chemistry , catalysis , computer science , programming language
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.