Download or read book Palladium-catalyzed Heck Reaction and Tandem Cross Coupling Reactions for Heterocycle Synthesis written by Yuanqing Fang and published by . This book was released on 2007 with total page 1130 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have obtained a tetracyclic Heck product with a formal anti-beta -hydride elimination during our post-ARO Pd-catalyzed derivatization studies of dihydronaphthalenes. We found that the yield for this Heck reaction was highly base-dependent, with DABCO being optimal. The catalyst combination of Pd2(dba)3/HP(tBu)3·BF 4 and DABCO was highly efficient for this intramolecular Heck reaction under very mild conditions. Additionally, we observed tandem double Heck reactions, which selectively functionalize two C-Br bonds intra- and intermolecularly. We further developed the concept of selective intramolecular and intermolecular cross-couplings using more general gemdihaloolefin systems, which subsequently led to the development of a variety of heterocycle forming reactions. A tandem C-N/Suzuki coupling of a gemdihalovinylaniline and organoboron reagents including aryl, heteroaryl, alkenylboronic acids (or borate esters) and alkyl boranes afforded a variety of 2-substituted indoles in good to excellent yield. This new method of indole synthesis tolerated various functional groups on all positions of the indole moiety. The orthogonal approach of the sequential copper and palladium-mediated synthesis of 1,2-diarylindoles exploited the availability of diverse organoboron reagents. This new method was successfully applied for the synthesis of three Merck KDR kinase inhibitors in very good overall yields. The Pd-catalyzed tandem couplings of gemdihalovinyl systems were further extended for the synthesis of (1) 2-carbonyl indoles via a C-N coupling, carbonylation, and Suzuki sequence, (2) 2-vinyl indoles via a C-N coupling/Heck reaction sequence, and (3) 2 alkynyl indoles via a C-N/Sonogashira coupling sequence. Furthermore, a Cu-catalyzed tandem Goldberg reaction was developed for the synthesis of imidazoindolones from amino acid-tethered gemdibromoolefins. Preliminary studies towards a modular synthesis of azaindoles from N'-Boc- N'-gemdibromovinyl pyridylamine via a sequential Suzuki/direct arylation protocol was also explored. This new tandem coupling reaction was also successfully extended to two other pharmaceutically important families of heterocycles, azaindoles and thienopyrroles. Suitable substituents (such as alkyl, Boc, and Cbz) on the amino group of the substrate were essential to prevent catalyst poisoning during the tandem process.