title: Photochemical reaction of N,N-dimethyl-4-chloroaniline with dienes: new synthetic paths via a phenyl cation.
abstract: The irradiation of N,N-dimethyl-4-chloroaniline in the presence of open-chain dienes in acetonitrile leads to addition of the aminophenyl and chloro groups across one of the double bonds; transannular cyclization takes place with cyclic dienes, leading to an arylnortricyclene from norbornadiene and to 1-arylbicyclo[3.3.0]octanes from 1,5-cyclooctadiene. The reaction proceeds by photoheterolysis of the chloroaniline to yield the 4-aminophenyl cation and addition to a CdoublebondC . The chemistry of the adduct cation depends on structure and medium, involving ion pairs in MeCN and solvated ions in CF(3)CH(2)OH. In the latter solvent, formation of ethers from open-chain alkenes is accompanied by Wagner-Meerwein hydride shift. In acetonitrile, the cation from cyclooctadiene partitions between deprotonation and Ritter addition, while the one from norbornadiene is reduced; both cations undergo nucleophilic addition in trifluoroethanol. The relevance of these cationic reactions under unusually mild conditions is discussed.
authors.affiliation: Department of Organic Chemistry, University of Pavia, via Taramelli 10, Italy.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Guizzardi
authors.forename: Mariella
authors.initials: M
authors.lastname: Mella
authors.forename: Maurizio
authors.initials: M
authors.lastname: Fagnoni
authors.forename: Angelo
authors.initials: A
authors.lastname: Albini