Decarboxylative Aldol Reactions of Allyl β-Keto Esters via Heterobimetallic Catalysis
Sha Lou, John A. Westbrook and Scott E. Schaus*
*Department of Chemistry, Metcalf Center for Science and Engineering, Boston
University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, Email:
seschaus
bu.edu
S. Lou, J. A. Westbrook, S. E. Schaus, J. Am. Chem. Soc., 2004, 126, 11440-11441.
DOI: 10.1021/ja045981k
Abstract
Mild and selective heterobimetallic-catalyzed decarboxylative aldol reactions of allyl β-keto esters with aldehydes are promoted by Pd(0)- and Yb(III)-DIOP complexes at room temperature. The optimized reaction conditions require the addition of both metals.
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Details
The document discusses the development of a heterobimetallic catalyst system for decarboxylative aldol reactions of allyl β-keto esters and aldehydes. The research, conducted by Sha Lou, John A. Westbrook, and Scott E. Schaus at Boston University, focuses on overcoming challenges in direct aldol reactions, particularly the selective formation of enolates. Initial experiments using Pd(0) catalysts yielded low product due to competing reactions. However, the addition of metal chloride salts, particularly YbCl3, significantly improved yields. The optimized conditions involved 5 mol % Pd(0), 5 mol % YbCl3, and 10 mol % DIOP, achieving up to 93% yield. The reaction proved effective for various aldehydes, including aliphatic, olefin-containing, and benzyl ethers, with some requiring additional YbCl3 for higher conversion. The proposed catalytic cycle involves both Yb(III) and Pd(0) facilitating the formation of the aldol adduct. The study highlights the potential of heterobimetallic catalysis in organic synthesis, with future research aimed at expanding the reaction scope. The work was supported by Boston University, Amgen, and an NSF CAREER Grant. Experimental procedures and compound characterizations are available online.
Key Words
β-hydroxy ketones, decarboxylation
ID: J48-Y2004-1710
