2,3-Disubstituted and 2,3,5-Trisubstituted Benzofurans by Regioselective Pd-Catalyzed Cross-coupling Reactions; a Short Synthesis of Eupomatenoid-15
- 31 December 2001
- journal article
- letter
- Published by Georg Thieme Verlag KG in Synlett
- Vol. 2001 (08) , 1284-1286
- https://doi.org/10.1055/s-2001-16052
Abstract
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.Keywords
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