SYNTHESIS VIA VINYL SULFONES .72. SULFONES AS RADICAL PROGENITORS - AN UNPRECEDENTED EXAMPLE OF HOMOLYTIC SULFONE CLEAVAGE FACILITATED BY O-STANNYL SUBSTITUTION OF ARYL SULFONES
Pc. Vandort et Pl. Fuchs, SYNTHESIS VIA VINYL SULFONES .72. SULFONES AS RADICAL PROGENITORS - AN UNPRECEDENTED EXAMPLE OF HOMOLYTIC SULFONE CLEAVAGE FACILITATED BY O-STANNYL SUBSTITUTION OF ARYL SULFONES, Journal of organic chemistry, 62(21), 1997, pp. 7137-7141
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.