4747-13-1Relevant articles and documents
New Surprises with Fischer Carbene Complexes: Formal [3 + 2] Cycloadditions with and without Preceding Carbene-Ligand Metathesis
Hoffmann, Matthias,Buchert, Matthias,Reissig, Hans-Ulrich
, p. 283 - 285 (1997)
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Ketal derivative of drug and preparation method thereof, pharmaceutical composition and application
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Paragraph 0139-0141, (2021/02/10)
The invention relates to a ketal derivative of a drug, and a preparation method thereof, a pharmaceutical composition and application. The ketal derivative comprises a compound as shown in a formula (I) (See the specification), a racemate, a stereoisomer, a tautomer or pharmaceutically acceptable salts thereof. The ketal derivative provided by the invention can significantly improve the physical,chemical and/or pharmaceutical properties of an original starting drug.
Coupling Reaction of Enol Derivatives with Silyl Ketene Acetals Catalyzed by Gallium Trihalides
Nishimoto, Yoshihiro,Kita, Yuji,Ueda, Hiroki,Imaoka, Hiroto,Chiba, Kouji,Yasuda, Makoto,Baba, Akio
supporting information, p. 11837 - 11845 (2016/08/05)
A cross-coupling reaction between enol derivatives and silyl ketene acetals catalyzed by GaBr3took place to give the corresponding α-alkenyl esters. GaBr3showed the most effective catalytic ability, whereas other metal salts such as BF3?OEt2, AlCl3, PdCl2, and lanthanide triflates were not effective. Various types of enol ethers and vinyl carboxylates as enol derivatives are amenable to this coupling. The scope of the reaction with silyl ketene acetals was also broad. We successfully observed an alkylgallium intermediate by using NMR spectroscopy, suggesting a mechanism involving anti-carbogallation among GaBr3, an enol derivative, and a silyl ketene acetal, followed by syn-β-alkoxy elimination from the alkylgallium. Based on kinetic studies, the turnover-limiting step of the reaction using a vinyl ether and a vinyl carboxylate involved syn-β-alkoxy elimination and anti-carbogallation, respectively. Therefore, the leaving group had a significant effect on the progress of the reaction. Theoretical calculations analysis suggest that the moderate Lewis acidity of gallium would contribute to a flexible conformational change of the alkylgallium intermediate and to the cleavage of the carbon?oxygen bond in the β-alkoxy elimination process, which is the turnover-limiting step in the reaction between a vinyl ether and a silyl ketene acetal.