Download or read book Palladium-catalyzed Synthesis of Heterocycles and Highly Functionalized Polycyclics written by Xiaojun Han and published by . This book was released on 1998 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt: Palladium catalyzes the regio- and stereoselective annulation of allenes by vinylic halides bearing tertiary alcohol and p-toluenesulfonamide groups to produce a variety of 5- and 6-membered ring heterocycles containing a 1,3-diene moiety. In addition, the palladium-catalyzed reaction of N-(2-iodo-2-alkenyl)--P-toluenesulfonamides with diphenylacetylene or 4,4-dimethyl-2-pentyne affords pyrolidine derivatives containing a 1,3-diene moiety, or unexpected 2-alkenyl substituted [Alpha, Beta-]unsaturated aldehydes. These synthetically useful intermediates are difficult to prepare or inaccessible by other existing methodology. A number of 3,4,6-tri- and 3,4,5,6-tetrasubstituted [Alpha]-pyrones have been prepared in good yields by the reaction of vinylic iodides or triflates bearing ester functionality with internal alkynes in the presence of a palladium catalyst. The methodology provides an especially simple, convenient, and regioselective route to [Alpha]-pyrones containing aryl, silyl, tert.-alkyl and other hindered groups.