Translator Disclaimer
1 September 2006 Mechanistic Studies on the Photochemical Deprotection of 3′,5′-Dimethoxybenzoin Esters
Author Affiliations +
Abstract

Several mechanistic alternatives proposed for the photochemical deprotection of dimethoxybenzoin esters are presented. Both experimental and theoretical evidence suggest the mechanism is heterolysis of the singlet excited state to form a carboxylate and the α-ketocation. The α-ketocation has been observed by transient spectroscopy. We propose the α-ketocation undergoes electrocyclization to an intermediate with extended conjugation, whose deprotonation gives the observed benzofuran product. A Brønsted study of the rates of benzofuran formation with dimethoxybenzoin esters derived from acids of varying pKa shows the rate is independent of the basicity of the leaving group. In this multistep reaction, benzofuran formation by a final deprotonation is slower than α-ketocation generation.

Michael C. Pirrung, Tong Ye, Zheng Zhou, and John D. Simon "Mechanistic Studies on the Photochemical Deprotection of 3′,5′-Dimethoxybenzoin Esters," Photochemistry and Photobiology 82(5), 1258-1264, (1 September 2006). https://doi.org/10.1562/2006-02-07-RA-798
Received: 7 February 2006; Accepted: 2 June 2006; Published: 1 September 2006
JOURNAL ARTICLE
7 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top