Burns, NoahWitten, Michael R.Jacobsen, Eric2012-05-142011Burns, Noah Z., Michael R. Witten, and Eric N. Jacobsen. 2011. Dual catalysis in enantioselective oxidopyrylium-based [5 + 2] cycloadditions. Journal of the American Chemical Society 133(37): 14578–14581.0002-7863http://nrs.harvard.edu/urn-3:HUL.InstRepos:8737994A new method is reported for effecting catalytic enantioselective intramolecular [5+2] cycloadditions based on oxidopyrylium intermediates. The dual catalyst system consists of a chiral primary aminothiourea and a second achiral thiourea. Experimental evidence points to a new type of cooperative catalysis with each species being necessary to generate a reactive pyrylium ion pair which undergoes subsequent cycloaddition with high enantioselectivity.en-UScycloaddition reactionsorganocatalysisdiastereoselective synthesesenantioselective synthesesmulti-membered O,S-heterocyclesJournal Article2012-05-1410.1021/ja206997e