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Powerful Ti-Crossed Claisen Condensation between Ketene Silyl Acetals or Thioacetals and Acid Chlorides or Acids

Akira Iida, Syogo Nakazawa, Tomohito Okabayashi, Atsushi Horii, Tomonori Misaki and Yoo Tanabe*

*Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan, Email:

A. Iida, S. Nakazawa, T. Okabayashi, A. Horii, T. Misaki, Y. Tanabe, Org. Lett., 2006, 8, 5215-5218.

DOI: 10.1021/ol0619361


A Ti-crossed Claisen condensation between ketene silyl (thio)acetals and acid chlorides gave α-monoalkylated (thio)esters and thermodynamically unfavorable α,α-dialkylated β-keto (thio)esters in good yield. Addition of N-methylimidazole enhances the reactivity of less reactive ketene silyl acetals. The protocol was extended to the direct condensation of ketene silyl acetals with carboxylic acids.

see article for more reactions

see article for more examples

Mild and Efficient Pentafluorophenylammonium Triflate (PFPAT)-Catalyzed C-Acylations of Enol Silyl Ethers or Ketene Silyl (Thio)Acetals with Acid Chlorides

A. Iida, J. Osada, R. Nagase, T. Misaki, Y. Tanabe, Org. Lett., 2007, 9, 1859-1862.

Key Words

Claisen Condensation. Ketocarboxylic Esters, Thioesters

ID: J54-Y2006-3580