title: GaCl(3)-catalyzed insertion of diazene derivatives into the cyclopropane ring.
abstract: GaCl3 has been found to efficiently catalyze the formal cycloadditions of diazene derivatives 6 onto 2-arylcyclopropane-1,1-dicarboxylates 5, giving rise to the pyrazolidine derivatives 7. The insertion into the cyclopropane ring proceeds with complete regioselectivity to furnish 5-arylpyrazolidine-1,2,3,3-tetracarboxylates exclusively; however, the cis-configured azo compound N-phenyltriazolinedione gave the two possible regioisomeric pyrazolidine derivatives in ratios varying from 1:1.5 to 1:3. Conceivable mechanisms of these transformations are being discussed.
authors.affiliation: Institut für Organische und Biomolekulare Chemie der Georg-August-Universität Göttingen, Tammannstrasse 2, D-37077 Göttingen, Germany.
authors.forename: Vadim S
authors.initials: VS
authors.lastname: Korotkov
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Larionov
authors.forename: Anja
authors.initials: A
authors.lastname: Hofmeister
authors.forename: Jörg
authors.initials: J
authors.lastname: Magull
authors.forename: Armin
authors.initials: A
authors.lastname: de Meijere