Clark JS, * Boyer A, Aimon A, García PE, Lindsay DM, Symington AD. F, Danoy Y. University of Glasgow, UK
Organocatalytic Synthesis of Highly Substituted Furfuryl Alcohols and Amines.
Angew. Chem. Int. Ed. 2012;
51: 12128-12131
Key words
thiophene - highly substituted furans - nucleophilic activation
Significance
The authors present an organocatalytic approach for the synthesis of highly substituted furfuryl alcohols and amines in good to excellent yield. The reaction is catalyzed by tetrahydrothiophene (2), using a Lewis base for the activation of the alkynylcarbonyl derivatives 1. In contrast to 2, other Lewis bases such as DABCO or Bu3P led to decomposition.
Comment
While electrophilic metal-catalyzed furan syntheses are common, organocatalytic approaches are rare. Inspired by the work of Krische (J. Am. Soc. Chem. 2004, 4118) and Kuroda (Tetrahedron 2004, 1913), Clark and co-workers applied a Lewis base activation concept for their reaction. By using tetrahydrothiophene (2) as a catalyst, an enolate is formed that cyclizes to a sulfur ylide containing furan which can react with different nucleophiles. This method can also be used for a multi-component domino synthesis of substituted furans.
