Microwave-Assisted Paal-Knorr Reaction - Three-Step Regiocontrolled Synthesis of Polysubstituted Furans, Pyrroles and Thiophenes
Giacomo Minetto, Luca F. Raveglia, Alessandro Sega, Maurizio Taddei*
*Dipartimento Farmaco Chimico Tecnologico, UniversitÓ degli Studi di Siena, Via A. Moro, 53100 Siena, Italy, Email: taddei.munisi.it
G. Minetto, L. F. Raveglia, A. Sega, M. Taddei, Eur. J. Org. Chem., 2005, 5277-5288.
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An efficient and highly versatile microwave-assisted Paal-Knorr condensation of various 1,4-diketones gave furans, pyrroles and thiophenes in good yields. In addition, transformations of the methoxycarbonyl moiety, such as Curtius rearrangement, hydrolysis to carboxylic acid, or the conversion into amine by reaction with a primary amine in the presence of Me3Al, are described.
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