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
[GRAPHICS]Highly chemo-, diastereo-, and enantioselective borohydride reduction of 2-substituted-1,3-diketones was achieved in the presence of the optically active beta -ketoiminato cobalt complex catalysts to afford the optically active 2-substituted-3-hydroxyketones. The present catalytic and enantioselective reduction could provide an alternative potential for preparation of optically active ant aldol-type compounds.
A New Method For the Construction of .alpha.-Diazo ketones
作者:Douglass F. Taber、D. Mark Gleave、R. Jason Herr、Kimberly Moody、Michael J. Hennessy
DOI:10.1021/jo00112a064
日期:1995.4
Taber Douglass F., Gleave D. Mark, Herr R. Jason, Moody Kimberly, Henness+, J. Org. Chem, 60 (1995) N 7, S 2283-2285
作者:Taber Douglass F., Gleave D. Mark, Herr R. Jason, Moody Kimberly, Henness+
DOI:——
日期:——
Enantioselective Borohydride Reduction Catalyzed by Optically Active Cobalt Complexes
作者:Tohru Yamada、Takushi Nagata、Kiyoaki D. Sugi、Kiyotaka Yorozu、Taketo Ikeno、Yuhki Ohtsuka、Daichi Miyazaki、Teruaki Mukaiyama
DOI:10.1002/chem.200304794
日期:2003.9.22
enantioselective borohydride reduction of aromatic ketones or imines to the corresponding alcohols was developed in the presence of a catalytic amount of an opticallyactive cobalt(II) complex catalyst. This enantioselective reduction is carried out using a precisely premodified borohydride with alcohols such as tetrahydrofurfuryl alcohol, ethanol and methanol. High optical yields are obtained by choosing