R. Munusamy et al., Cathodic reduction of N-(2-iodophenyl)-N-alkylcinnamides: a novel sequential electrochemical radical cyclisation and hydroxylation, J CHEM S P2, (7), 2001, pp. 1154-1166
Citations number
60
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
In recent years, intramolecular aryl radical cyclisation has emerged as a u
seful route for the synthesis of benzannulated heterocycles and carbocycles
. The aryl radicals are generated in situ from aryl halides (iodides or bro
mides) with tributylstannyl hydride-AIBN, SmI2, Co(I) or under photochemica
l conditions. The present work envisages the generation of aryl radicals by
cathodic reduction of the carbon-iodine bond of N-(2-iodophenyl)-N-alkylci
nnamides and their intramolecular cyclisation. The cathodic reduction of N-
(2-iodophenyl)-N-alkylcinnamides under deaerated conditions in DMF gave 1-a
lkyl-3-benzylindolin-2-ones regioselectively and in the presence of oxygen
yielded surprisingly 1-alkyl-3-hydroxy-3-benzylindolin-2-ones. Both these p
roducts were formed by a 5-exo-trig process in good yields. A mechanism for
the formation of the products has been proposed through the use of cyclic
voltammetry, coulometry and controlled-potential electrolysis as well as de
uterium labelling.