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Synfacts 2010(11): 1263-1263  
DOI: 10.1055/s-0030-1258809
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Asymmetric Wacker-Type Cyclization Catalyzed by Pd-SPRIX

Contributor(s):Hisashi Yamamoto, Kimberly Griffin
K. Takenaka, S. C. Mohanta, M. L. Patil, C. V. L. Rao, S. Takizawa, T. Suzuki, H. Sasai*
Osaka University, Japan
Enantioselective Wacker-Type Cyclization of 2-Alkenyl-1,3-diketones Promoted by Pd-SPRIX Catalyst
Org. Lett.  2010,  12:  3480-3483  
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Publication History

Publication Date:
21 October 2010 (online)

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Key words

Wacker cyclization - diketones - palladium

Significance

Diketones have previously been shown to undergo Wacker-type cyclizations: 5-exo-trig cyclizations lead to furan rings, and pyran rings are formed through 6-endo-trig cyclizations. The first enantioselective 6-endo-trig Wacker-type cyclization is described here, catalyzed by a palladium spiro bis(isoxazoline) (SPRIX) complex.

Comment

This clever use of palladium cyclization generates quaternary stereocenters. Alkyl and aryl groups on the olefin as well as disubstituted alkenyl chains all underwent cyclization. Deuterium studies led the authors to propose a catalytic ­cycle for the process, which lead to product 3 over product 2 due to steric clash during β-hydride elimination.

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