Free Radical Self-Immolative 1,2-Elimination and Reductive Desulfonylation of Aryl Sulfones Promoted by Intramolecular Reactions with Ortho-Attached Carbon-Centered Radicals(1)

P. C. Van Dort; P. L. Fuchs

doi:10.1021/jo970445e

Free Radical Self-Immolative 1,2-Elimination and Reductive Desulfonylation of Aryl Sulfones Promoted by Intramolecular Reactions with Ortho-Attached Carbon-Centered Radicals(1)

J Org Chem. 1997 Oct 17;62(21):7142-7147. doi: 10.1021/jo970445e.

Authors

P. C. Van Dort¹, P. L. Fuchs

Affiliation

¹ Department of Chemistry, Purdue University, West Lafayette, Indiana 47907.

PMID: 11671818
DOI: 10.1021/jo970445e

Abstract

Aryl sulfones bearing an o-(bromomethyl)dimethylsilyl moiety (1), when heated with AIBN and tributyltin hydride, suffer radical elimination under mild conditions to give olefins and stannyl sulfinate 7 in high yield. The mechanism is shown to proceed via intramolecular beta-sulfonyl hydrogen abstraction by o-silylmethylene radical 2. This step also shows a large deuterium isotope effect of 12:1. In contrast, radical intermediate 24, generated by tris(trimethylsilyl)silane radical addition to o-allylsilane 23, undergoes intramolecular attack on the sulfone, resulting in homolytic sulfone cleavage to afford reduced products and cyclic sulfone byproduct 25.