Synthesis 2010(23): 4061-4067  
DOI: 10.1055/s-0030-1258279
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Diastereoselective Synthesis of trans-2,3,6,7-Tetrahydro-4(5H)-benzofuran­ones and trans-2,3-Dihydrofurocoumarins via Pyridinium Ylide Assisted Tandem Reactions

Ying Han, Hong Hou, Rong Yao, Qin Fu, Chao-Guo Yan*
College of Chemistry & Chemical Engineering, Yangzhou University, Yangzhou 225002, P. R. of China
Fax: +86(514)87975244; e-Mail: cgyan@yzu.edu.cn;
Further Information

Publication History

Received 5 July 2010
Publication Date:
30 September 2010 (online)

Abstract

An efficient, one-pot tandem reaction of pyridine, an α-haloacetate, an aromatic aldehyde and cyclohexane-1,3-dione, dimedone or 4-hydrocoumarin in acetonitrile using 1,4-diazabicyclo[2.2.2]octane as a basic catalyst is described. The products, 2,3,6,7-tetrahydro-4(5H)-benzofuranones and 2,3-dihydrofurocoumarins, are obtained in a diastereoselective manner via a mechanism involving in situ formation of a pyridinium ylide. ¹H NMR spectroscopy and single crystal X-ray analysis indicates that the products are formed exclusively as the trans isomers.

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Crystallographic data for compounds 4a (CCDC 764133), 4f (CCDC 764134), 4j (CCDC 764136) and 4m (CCDC 764135) have been deposited at the Cambridge Crystallographic Data Centre.