Synlett 2011(11): 1618-1622  
DOI: 10.1055/s-0030-1260785
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Further Developments of an Enantioselective Palladium-Catalyzed Polyene Cyclization: Surprising Solvent and Ligand Effects

Daniela Lucciola, Brian A. Keay*
Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
Fax: +1(403)2899488; e-Mail: keay@ucalgary.ca;
Further Information

Publication History

Received 29 March 2011
Publication Date:
10 June 2011 (online)

Abstract

The enantioselectivity of a Pd-catalyzed domino Heck-Mizoroki cyclization is dramatically enhanced by ligand and solvent choice. Electron-deficient ligands such as (R)-DIFLUORPHOS gave 5 in %ee values ranging from 94% ee to >99% ee. EtOH was found to be superior to other solvents traditionally used in Heck-Mizoroki reactions, generally showing increases in enantioselecti­vity when compared to toluene. It is also shown that microwave heating accelerates the reaction in either solvent and allows for a longer catalyst lifetime without eroding the %ee.

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