Indium Tribromide Catalyzed Cross-Claisen Condensation between Carboxylic Acids and Ketene Silyl Acetals Using Alkoxyhydrosilanes
作者:Yoshihiro Nishimoto、Aya Okita、Makoto Yasuda、Akio Baba
DOI:10.1002/anie.201104140
日期:2011.9.5
Acylations achieved: The title reaction between carboxylic acids and ketene silyl acetals has been accomplished (see scheme). The additive, (MeO)3SiH, is believed to play an important role in the promotion of the condensation reaction. This reaction system was compatible with a diverse range of functional groups, including alkenes, alkynes, chlorides, alcohols, esters, and nitro groups.
Mild and Efficient Pentafluorophenylammonium Triflate (PFPAT)-Catalyzed C-Acylations of Enol Silyl Ethers or Ketene Silyl (Thio)Acetals with Acid Chlorides
A pentafluorophenylammonium triflate (PFPAT) catalyst (5 mol %) successfully promoted C-acylation of enol silyl ethers with acid chloride to produce various beta-diketones (12 examples; 62-92% yield). Similarly, C-acylation of ketenesilylacetals or ketenesilyl thioacetals (i.e., crossed Claisen condensation) proceeded smoothly to provide not only alpha-monoalkylated beta-keto (thio)esters but also
[Structure: see text] A powerful Ti-crossed Claisen condensation between ketene silyl acetals (KSAs) and acid chlorides was successfully performed to give alpha-monoalkylated esters and thermodynamically unfavorable (less accessible) alpha,alpha-dialkylated beta-keto esters in good yield (46 examples; 41-98% yield). A closely related reaction between ketene silyl thioacetals (KSTAs) and acid chlorides also