ORGN 661 |
| A set of novel methodologies for the synthesis of furans, pyrroles, and fused pyrroloheterocycles through transition metal-catalyzed cycloisomerizations of alkynyl ketones and –imines has been developed. We have also discovered a series of unusual 1,2-migrations of thio-, acyloxy-, phosphatyloxy-, and sulfonyloxy groups, as well as the halo-group, in allenyl systems. These novel migrations, incorporated into the cycloisomerization cascade, allowed for efficient construction of tri- and tetrasubstituted furans and pyrroles, heterocyclic units unavailable via traditional cycloisomerization techniques. Remarkably, it was demonstrated, that the cycloisomerization of an ambident allenyl ketone in the presence of Au(I)- or Au(III)-catalyst proceeded via the selective migration of either hydrogen or halogen atom leading to 5-halo- or 4-halosubstituted furans exclusively. The scope, selected synthetic applications, and mechanisms of these and other novel cycloisomerization methodologies will be discussed. |
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Modern Acetylene Chemistry
1:20 PM-4:55 PM, Wednesday, 13 September 2006 Moscone Center -- Room 134, Oral
Division of Organic Chemistry |