Issue 2, 2003

Cationic arylation through photo(sensitised) decomposition of diazonium salts. Chemoselectivity of triplet phenylcations

Abstract

The photodediazoniation of some 4-X-phenyldiazonium tetrafluoborates in MeCN leads to the singlet phenyl cations (X = H, tert-butyl, NMe2, CN), which add to the solvent yielding the corresponding acetanilides. Triplet sensitisation, however, leads to the triplet phenyl cation, which is reduced in neat solvent and is trapped by π nucleophiles (allyltrimethylsilane and benzene), resulting in an ionic analogue of the Meerwein or Gomberg arylations. With the 4-nitro derivative intersystem crossing prevails over dediazoniation from the singlet and with the 4-cyano competes with it, so that in those cases the triplet phenyl cation is formed also upon direct irradiation.

Graphical abstract: Cationic arylation through photo(sensitised) decomposition of diazonium salts. Chemoselectivity of triplet phenyl cations

Article information

Article type
Communication
Submitted
21 Oct 2002
Accepted
29 Nov 2002
First published
11 Dec 2002

Chem. Commun., 2003, 216-217

Cationic arylation through photo(sensitised) decomposition of diazonium salts. Chemoselectivity of triplet phenyl cations

S. Milanesi, M. Fagnoni and A. Albini, Chem. Commun., 2003, 216 DOI: 10.1039/B210243A

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