R. Novikov, Yu. V. Tomilov
Nov 1, 2013
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0
Influential Citations
15
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Journal
Helvetica Chimica Acta
Abstract
In the presence of a catalytic amount of GaCl3, dimethyl 2-(naphthalen-1-yl)cyclopropane-1,1-dicarboxylate 5 undergoes selective [3+2]-annulation-type dimerization to give a polysubstituted cyclopentane containing two naphthalenyl substituents in the vicinal position (Scheme 2). Treatment of the same cyclopropane with an equimolar amount of GaCl3⋅THF results in dimerization with electrophilic attack on each of the benzene rings to give [3+3] and [3+4] annulation products. The latter represent a new type of dimerization of donoracceptor cyclopropanes. Finally, under conditions of double catalysis with GaCl3, 3,3,5,5-tetrasubstituted 4,5-dihydropyrazole, this cyclopropane-dicarboxylate undergoes stereospecific dimerization as a result of electrophilic ipso-attack to give a tetracyclic pentaleno[6a,1-a]naphthalene derivative (Scheme 5). Possible reaction mechanisms are proposed.