Cooperative N-Heterocyclic Carbene/Lewis Acid Catalysis for Highly Stereoselective Annulation Reactions with Homoenolates
Benoit Cardinal-David, Dustin E. A. Raup and Karl A. Scheidt*
*Department of Chemistry, Center for Molecular Innovation and Drug Discovery, Chemistry of Life Processes Institute, Northwestern University, Silverman Hall, Evanston, Illinois 60208, Email: scheidtnorthwestern.edu
B. Cardinal-David, D. E. A. Raup, K. A. Scheidt, J. Am. Chem. Soc., 2010, 132, 5345-5347.
DOI: 10.1021/ja910666n (free Supporting Information)
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N-Heterocyclic carbene/Lewis acid cooperative catalysis provides access to cis-1,3,4-trisubstituted cyclopentenes from enals and chalcone derivatives with high levels of diastereoselectivity and enantioselectivity. The presence of Ti(OiPr)4 as Lewis acid enables an efficient substrate preorganization, which translates into high levels of diastereoselectivity.
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