Efficient One-Pot Synthesis of N-Containing Heterocycles by Multicomponent Coupling of Silicon-Tethered Diynes, Nitriles, and Isocyanides through Intramolecular Cyclization of IminoacylZr Intermediates

✍ Scribed by Shaoguang Zhang; Wen-Xiong Zhang; Zhenfeng Xi

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 384 KB
• Volume: 16
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.201000708

✦ Synopsis

Abstract

An efficient multicomponent synthesis of 5‐azaindoles and dihydropyrrolo[3,2‐c]azepines was achieved by zirconocene‐mediated coupling of silicon‐tethered diynes, nitriles, and isocyanides. The synthesis, structures, and intramolecular cyclization of mono‐ and bis(iminoacyl)Zr intermediates were investigated to elucidate the reaction process. Upon hydrolysis, the isolated mono(iminoacyl)Zr intermediates underwent intramolecular cyclization to afford tetrasubstituted 5‐azaindoles, whereas intramolecular cyclization of bis(iminoacyl)Zr intermediates led to the formation of dihydropyrrolo[3,2‐c]azepines. The structure of a bis(iminoacyl)Zr intermediate, formed through insertion of two molecules of CyNC into the ZrC bond, and structures of two dihydropyrrolo[3,2‐c]azepines were characterized by single‐crystal X‐ray structural analysis.