2011 Theses Doctoral

Development of Palladium-Catalyzed and Iodine-Mediated Formal [4+1] Annulation Protocols. Progress toward a New Fulvene-Based Organocatalytic Platform for Carbonyl α-Functionalization

Coscia, Rockford Winthrop

The development of a new palladium-catalyzed [4+1] annulation protocol is described. This process involves an oxidative palladium-catalyzed intramolecular vinylcyclopropanation of dienyl beta-ketoesters followed by a magnesium iodide-mediated vinylcyclopropane-cyclopentene rearrangement. The cyclopropanation makes use of magnesium perchlorate to increase reactivity at the alpha-carbon of the beta-ketoesters. The protocol has been demonstrated to be effective in the annulation of a number of substituted dienyl beta-ketoesters.

The development of a one-pot iodine-mediated Lewis acid-promoted [4+1] annulation protocol is described. The protocol utilizes an iodine-mediated vinylcyclopropanation of dienyl beta-ketoesters followed by vinylcyclopropane-cyclopentene rearrangement. Magnesium perchlorate, used to promote the first reaction and iodide are used to effect the vinylcyclopropane-cyclopentene rearrangement.

The application of the protocol to a broad range of substituted dienyl beta-ketoesters is described. Progress toward a fulvene-based organocatalytic paradigm has been made. The diastereoselective alpha-allylation of a camphor-derived indenyl fulvene has been demonstrated. The reversible formation of fulvenes from carbonyls and electron deficient cyclopentadienes under mild nucleophilic amines catalysis has also been demonstrated and applied to several aryl and alkenyl aldehydes. Transfulvenation between benzaldehyde- and cinnamaldehyde-derived fulvenes has also been demonstrated.