18349-19-4Relevant academic research and scientific papers
Development and Mechanistic Studies of the Iridium-Catalyzed C?H Alkenylation of Enamides with Vinyl Acetates: A Versatile Approach for Ketone Functionalization
Dong, Guangbin,Liu, Peng,Qi, Xiaotian,Zhou, Bo
supporting information, p. 20926 - 20934 (2021/08/18)
Ketone functionalization is a cornerstone of organic synthesis. Herein, we describe the development of an intermolecular C?H alkenylation of enamides with the feedstock chemical vinyl acetate to access diverse functionalized ketones. Enamides derived from various cyclic and acyclic ketones reacted efficiently, and a number of sensitive functional groups were tolerated. In this iridium-catalyzed transformation, two structurally and electronically similar alkenes—enamide and vinyl acetate—underwent selective cross-coupling through C?H activation. No reaction partner was used in large excess. The reaction is also pH- and redox-neutral with HOAc as the only stoichiometric by-product. Detailed experimental and computational studies revealed a reaction mechanism involving 1,2-Ir-C migratory insertion followed by syn-β-acetoxy elimination, which is different from that of previous vinyl acetate mediated C?H activation reactions. Finally, the alkenylation product can serve as a versatile intermediate to deliver a variety of structurally modified ketones.
Ce(3+)-Exchanged Montmorillonite (Ce(3+)-Mont) as a Useful Substrate-Selective Acetalization Catalyst
Tateiwa, Jun-ichi,Horiuchi, Hiroki,Uemura, Sakae
, p. 4039 - 4043 (2007/10/02)
The acetalization of carbonyl compounds with methanol was investigated in the presence of a cation-exchanged montmorillonite (M(n+)-mont; M(n+) = Ce(3+), Zr(4+), Fe(3+), Al(3+), Zn(2+), H(+) and Na(1+).Ce(3+)-mont was found to be the most effective catalyst for substrate-selective acetalization.Cyclohexanones, benzaldehydes, and acid-sensitive 2-furancarboxaldehyde were converted nearly quantitatively to the corresponding acetals in methanol at 25 deg C in the presence of Ce(3+)-mont.The substrates were activated by a Lewis acidic Ce(3+) cation in the interlayer space on the order of 1 kJ mol-1 as measured by FT-IR.The turnover number was estimated to be up to 2.6E3 based on the number of active acid sites in Ce(3+)-mont.
