2,3-Disubstituted and 2,3,5-Trisubstituted Benzofurans by Regioselective Pd-Catalyzed Cross-coupling Reactions; a Short Synthesis of Eupomatenoid-15

Thorsten Bach; Marc Bartels

doi:10.1055/s-2001-16052

Synlett 2001; 2001(8): 1284-1286
DOI: 10.1055/s-2001-16052

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2,3-Disubstituted and 2,3,5-Trisubstituted Benzofurans by Regioselective Pd-Catalyzed Cross-coupling Reactions; a Short Synthesis of Eupomatenoid-15

Thorsten Bach^* , Marc Bartels

^*Lehrstuhl für Organische Chemie I, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany; Fax + 49(0)89/28 91 33 15; E-mail: thorsten.bach@ch.tum.de

Abstract

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2,3-Dibromobenzofuran (1) and 2,3,5-tribromobenzofuran (2) undergo regioselective Sonogashira- and Negishi-type cross-coupling reactions at the 2-position. Subsequent substitution reactions at C-3 are possible for the cross-coupling products obtained from compound 1. A regioselective functionalization of the 3,5-dibromobenzofurans derived from substrate 2 was achieved by an halogen-metal exchange which occurred selectively at the 3-position. In a conclusive reaction step cross-coupling reactions at C-5 were used to build up 2,3,5-trisubstituted benzofurans. As an example, the synthesis of eupomatenoid-15 (8) is described.

catalysis - cross-coupling - heterocycles - palladium - regioselectivity

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