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Photochemical Reaction of N , N ‐Dimethyl‐4‐chloroaniline with Dienes: New Synthetic Paths via a Phenyl Cation
Author(s) -
Guizzardi Benedetta,
Mella Mariella,
Fagi Maurizio,
Albini Angelo
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200390178
Subject(s) - chemistry , medicinal chemistry , photochemistry
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 CC double bond. 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.