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Pure Appl. Chem., 2013, Vol. 85, No. 7, pp. 1479-1486

http://dx.doi.org/10.1351/PAC-CON-12-10-03

Published online 2013-04-25

Smooth photogeneration of α,n-didehydrotoluenes (DHTs)

Stefano Protti, Davide Ravelli, Maurizio Fagnoni and Angelo Albini*

PhotoGreen Lab, Department of Chemistry, University of Pavia, via Taramelli 12, 27100 Pavia, Italy

Abstract: Irradiation of the three isomeric (chlorobenzyl)trimethylsilanes in methanol–water generates the corresponding didehydrotoluenes (DHTs). The process involves expulsion of a chloride ion to give the triplet phenyl cation and ensuing elimination of the trimethylsilyl cation. This straightforward generation of DHT intermediates overcomes a shortcoming of previous methodology (cycloaromatization of enyne-allenes), which is limited to the meta-isomer, and opens the path for understanding the chemistry (and possibly the biological action) of these unusual intermediates.