New aromatic rearrangement accompanying ring closure of 2-arylpropylidenemalonodinitriles to 1-aminonaphthalene-2-carbonitriles

Cyclization and a rearrangement in concentrated sulfuric acid of 2-(4-subst ituted-phenyl)propylidenemalonodinitriles (1) into 1-amino-4-methyl-6-subst ituted-naphtalene-1-carbonitriles (5) appears to involve a series of steps such as ipso electrophilic attack of the protonated nitrile function on the para position of the phenyl group, opening of a spirobenzenium cation or i ts transformation, and ring reclosure to the naphthalene framework with par ticipation of the secondary alkyl carbocation as an active electrophile. (C ) 2001 Elsevier Science Ltd. All rights reserved.