Microwave-assisted generation and reactivity of aza- and diazafulvenium methide...

• Author(s): Soares, Maria I. L. ; Melo, Teresa M. V. D. Pinho e
• Date: 2008
• Persistent ID: http://hdl.handle.net/10316/4999
• Origin: Estudo Geral - Universidade de Coimbra
• Subject(s): Azafulvenium methide; Diazafulvenium methide; Pyrrole; Pyrazole; Sigmatropic [1,8]H shifts; 1,7-Electrocyclization; [8[pi]+2[pi]] Cycloaddition
• Document Type: Article
• Language: English

Description

Azafulvenium methides and diazafulvenium methides have been generated under microwave irradiation from 2,2-dioxo-1H,3H-pyrrolo[1,2-c]thiazoles and 2,2-dioxo-1H,3H-pyrazolo[1,5-c]thiazoles, respectively. Pericyclic reactions of these 1,7-dipole intermediates, namely, sigmatropic [1,8]H shifts, 1,7-electrocyclization or [8[pi]+2[pi]] cycloaddition led to the synthesis of a range of pyrrole and pyrazole derivatives. The first evidence for the azafulvenium methides by intermolecular trapping via [8[pi]+2[pi]] cycloaddition is reported. http://www.sciencedirect.com/science/article/B6THS-4SP3SM3-6/1/d6303d9db78919cfe9cd796c1a17d442