Synthesis of nitrogen heterocycles via palladium-catalyzed intramolecular cyclization

✍ Scribed by Richard C. Larock; Srinivasan Babu

• Publisher: Elsevier Science
• Year: 1987
• Tongue: French
• Weight: 224 KB
• Volume: 28
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)96710-8

✦ Synopsis

Catalytic amounts of Pd(OAc)2 in the presence of c-Bu4NC1, OMF and an appropriate Et3N) cyclize nitrogen-containing o-lodoaryl alkenes to indoles, quinolines, isoquinolines and isoquTnolones in short reaction times, under mild temperatures, and in high yields. Transition metal reagents have proven highly valuable for the cyclization of nitrogencontaining ortho-haloaryl alkenes to heterocycles. For example, cobalt' in stoichiometric amounts, or nicke12-5 and palladium6-8 catalysts have recently been employed in the synthesis of indoles (eq. 1). Oxindoles have similarly been prepared using Ni5*'-12 and Pd13,14 Co 32% Ni 46-73% CH, Pd 60-87% X = Cl, Br, I catalysts. Only the intramolecular Heck reactionsI using palladium proceed in decent yield free of side products, but even they require elevated temperatures and long reaction times. Perhaps because of these disadvantages, these reactions have not been widely employed, nor has