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Substituent effects on the rearrangements of cyclohexyl to cyclopentyl radicals involving avermectin-related radicals.

ABSTRACT: The rearrangement of a substituted cyclohexyl radical to a cyclopentylmethyl radical on the skeleton of avermectin B1 has been investigated using density functional (UB3LYP/6-31G(d)) and G3MP2B3 computational methods. The rearrangement is preferred when highly radical stabilizing groups are present at the 2- and 3-positions of the cyclohexyl radical. A substituent on the 3-position of the cyclohexyl radical enables ring-cleavage of the cyclohexyl radical, while a radical stabilizing substituent on the 2-position of the cyclohexyl radical stabilizes the final cyclopentylmethyl radical, enabling the overall rearrangement and reversing the normal thermodynamic preference for the hexenyl radical ring closure.

SUBMITTER: Luft JA

PROVIDER: S-EPMC2652414 | biostudies-literature | 2008 Nov

REPOSITORIES: biostudies-literature

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Substituent effects on the rearrangements of cyclohexyl to cyclopentyl radicals involving avermectin-related radicals.

Luft Jennifer A R JA Winkler Tammo T Kessabi Fiona M FM Houk K N KN

The Journal of organic chemistry 20081009 21

The rearrangement of a substituted cyclohexyl radical to a cyclopentylmethyl radical on the skeleton of avermectin B1 has been investigated using density functional (UB3LYP/6-31G(d)) and G3MP2B3 computational methods. The rearrangement is preferred when highly radical stabilizing groups are present at the 2- and 3-positions of the cyclohexyl radical. A substituent on the 3-position of the cyclohexyl radical enables ring-cleavage of the cyclohexyl radical, while a radical stabilizing substituent ...[more]

PMID: 18842059

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