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Synfacts 2006(3): 0277-0277  
DOI: 10.1055/s-2006-931985
Bioorganic Chemistry and Organocatalysis
© Georg Thieme Verlag Stuttgart · New York

Organocatalytic Mukaiyama Aldehyde Cross-Aldol Reactions

Contributor(s): Benjamin List, Daniela Kampen
M. B. Boxer, H. Yamamoto*
The University of Chicago, USA
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Publication History

Publication Date:
21 February 2006 (online)

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Significance

Organocatalytic Mukaiyama aldehyde cross-aldol reactions have been reported. Addition of tris(trimethylsilyl)silyl (TTMSS) enol ethers 1 to aldehydes in the presence of 0.05 mol% of triflimide or TTMSSNTf2 provides products of type 2 in high yields. Chiral aldehydes afford­ Felkin adducts for nonchelating α-substituents, chelation products for chelating α-substitu­ents, and syn products for β-substituents. Silyl enol ether 1 derived from propionaldehyde gives good syn:anti ratios. In addition, the first cascade Mukaiyama aldol synthesis has been developed. The use of 2.2 equivalents of acetaldehyde silyl enol ether 3 provides 2:1 adducts 4 in good yields and high syn diastereoselectivities.