ORGN 599 |
| The development of new synthetic strategies for the efficient construction of complex molecules containing multiple stereogenic centers is an important goal of research carried out in both academic and industrial laboratories. Tandem reactions can built a large degree of structural complexity into the target architecture, while producing less chemical wastes and minimizing the excessive handling. Organocatalytic enantioselective tandem processes are even more appealing due to their operational simplicity and environmental friendliness. In this poster, we disclose a new organocatalyzed enantioselective cascade Michael-aldol reactions that generate diverse, structurally and stereochemically complex benzothiopyrans in a highly concise fashion. The notable features of the process include: 1) the tandem reactions efficiently catalyzed by a chiral cinchona alkaloid thiourea via hydrogen bonding mediated catalysis using as low as 1 mol% catalyst loading in high yields (75-97%); 2) the generation of three new stereogenic centers with high enantio- (87-99% ee) and diastereoselectivities (>20:1 dr) in a one-pot transformation. |
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Materials, Devices and Switches, Metal-Mediated Reactions, Asymmetric Reactions, Total Synthesis, Biologically-Related Molecules and Processes
7:00 PM-9:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- La Louisiane, Blrm. C, Poster
Division of Organic Chemistry |