Synlett 2008(7): 1053-1057  
DOI: 10.1055/s-2008-1072583
LETTER
© Georg Thieme Verlag Stuttgart · New York

Intramolecular Palladium-Catalyzed Oxidative Coupling on Thiophene and Furan Rings: Determinant Role of the Electronic Availability of the Heterocycle

Egle M. Beccallia, Elena Borsinib, Gianluigi Broggini*b, Micol Rigamontib, Silvia Sottocornolab
a Istituto di Chimica Organica ‘A. Marchesini’, Facoltà di Farmacia, Università di Milano, via Venezian 21, 20133 Milano, Italy
b Dipartimento di Scienze Chimiche e Ambientali, Università dell’Insubria, via Valleggio 11, 22100 Como, Italy
Fax: +39(031)2386449; e-Mail: gianluigi.broggini@uninsubria.it;
Further Information

Publication History

Received 20 December 2007
Publication Date:
31 March 2008 (online)

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Abstract

The cyclization of N-allyl-N-carbetoxy-substituted aminothiophenes and furans was performed by intramolecular Pd(II)-catalyzed oxidative coupling. The process involves a nucleophilic attack of a heteroaromatic carbon to the internal carbon of the π-olefin complex through a 5-exo-trig ring-formation. Better conditions required PdCl2(MeCN)2 as catalyst, CuCl2 as co-catalyst and an environmentally friendly reoxidant such as O2 to promote the catalytic cycle.