SYNTHESIS VIA VINYL SULFONES .72. SULFONES AS RADICAL PROGENITORS - AN UNPRECEDENTED EXAMPLE OF HOMOLYTIC SULFONE CLEAVAGE FACILITATED BY O-STANNYL SUBSTITUTION OF ARYL SULFONES

Allylic aryl sulfones bearing an o-allyldialkylstannyl moiety (1b), wh en converted to stannyl radical la, suffer homolytic cleavage via intr amolecular attack of the stannyl radical on the sulfone. Allyl radical s generated in this manner can be utilized for further intramolecular radical cyclizations; thus the overall transformation can be viewed as an alkylative desulfonylation reaction. Previously unknown sulfonyl s tannane polymer 5 is generated as a byproduct. The o-dibutylstannyl ra dical derived from nonallylic aryl sulfone 15 does not suffer homolysi s but instead forms 9-membered macrocycle 19 via an intramolecular rea ction with the phenylacetylene group.