Synlett 2009(8): 1277-1280  
DOI: 10.1055/s-0028-1088132
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Palladium-Catalyzed Reaction of Arenediazonium Tetrafluoroborates with Methyl 4-Hydroxy-2-butenoate: An Approach to 4-Aryl Butenolides and an Expeditious Synthesis of Rubrolide E

Sandro Cacchi*, Giancarlo Fabrizi, Antonella Goggiamani, Alessio Sferrazza
Dipartimento di Chimica e Tecnologie del Farmaco, Università degli Studi ‘La Sapienza’, P. le A. Moro 5, 00185 Rome, Italy
Fax: +39(06)49912780; e-Mail: sandro.cacchi@uniroma1.it;
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Publication History

Received 10 February 2009
Publication Date:
08 April 2009 (online)

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Abstract

The palladium-catalyzed reaction of arenediazonium ­tetrafluoroborates with methyl 4-hydroxy-2-butenoate in MeOH under mild conditions gives 4-arylbutenolides usually in good to high yields through a domino vinylic substitution/cyclization process. The reaction tolerates a variety of useful substituents including the whole range of halogen substituents, nitro, ether, cyano, keto, and ester groups and can be performed as a one-pot process generating the arenediazonium salt in situ. By using this method, the marine antibiotic rubrolide E has been synthesized via an expeditious and efficient sequential protocol that omits the isolation of the butenolide intermediate (two operative steps, 52% overall yield).