Calcium-Catalyzed, Dehydrative, Ring-Opening Cyclizations of Cyclopropyl Carbinols Derived from Donor-Acceptor
Matthew J Sandridge1, Stefan France1,2
1School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
Abstract:
A calcium-catalyzed, dehydrative, ring-opening cyclization of (hetero)aryl cyclopropyl carbinols is reported. The cyclopropyl carbinols are prepared directly from the corresponding donor-acceptor (D-A) cyclopropanes. The calcium catalyst catalyzes the formation of putative (hetero)aryl cyclopropyl carbinyl cations that undergo ring-opening to allylcarbinyl cations. Subsequent intramolecular Friedel-Crafts reaction affords (hetero)aryl-fused cyclohexa-1,3-dienes in up to 97% yield. This approach represents the first example of catalysis for this intramolecular, dehydrative ring-opening cyclization and outperforms the previous reports using stoichiometric Lewis acids.
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