Radical Ion Probes. 8. Direct and Indirect Electrochemistry of 5,7-Di-tert-butylspiro[2.5]octa-4,7-dien-6-one and Derivatives

Document Type

Article

Publication Date

1-14-1998

Publication Source

Journal of the American Chemical Society

Volume Number

120

Issue Number

1

First Page

195

Last Page

202

Publisher

American Chemical Society

ISSN

0002-7863

Comments

This article was published while author Jason G. Gillmore was at the Virginia Polytechnic Institute and State University

Abstract

Results pertaining to the direct and indirect electrochemistry of 5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1a), 1-methyl-5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1b), and 1,1,-dimethyl-5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1c) are reported. Product analyses reveal that reduction of all these substrates leads to cyclopropane ring-opened products; ring opening occurs with modest selectivity leading to the more substituted (stable) distonic radical anion. The direct electrochemistry of these compounds is characterized by rate limiting electron transfer (with α ≈ 0.5), suggesting that while ring opening is extremely rapid, the radical anions do have a discrete lifetime (i.e., electron transfer and ring opening are not concerted). Utilizing homogeneous redox catalysis, rate constants for electron transfer between 1a, 1b, and 1c and a series of aromatic radical anions were measured; reduction potentials and reorganization energies were derived from these rate constants by using Marcus theory.

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