Silver-Mediated Cycloaddition of Alkynes with CF<sub>3</sub>CHN<sub>2</sub>: Highly Regioselective Synthesis of 3-Trifluoromethylpyrazoles
作者:Feng Li、Jing Nie、Long Sun、Yan Zheng、Jun-An Ma
DOI:10.1002/anie.201301870
日期:2013.6.10
Silver screen: The title reaction provides a convenient and efficient method for the construction of 5‐substituted 3‐trifluoromethylpyrazoles under mild reaction conditions. By using this protocol, the marketed drug Celecoxib (antiarthritic) could be easily synthesized (see scheme; DMF=N,N‐dimethylformamide).
A Unified Continuous Flow Assembly-Line Synthesis of Highly Substituted Pyrazoles and Pyrazolines
作者:Joshua Britton、Timothy F. Jamison
DOI:10.1002/anie.201704529
日期:2017.7.17
molecular diversity in short order. Continuous flowsynthesis enables the safe handling of diazoalkanes at elevated temperatures, and the use of aryl alkyne dipolarphiles under catalyst-free conditions. This assembly-line synthesis provides a flexible approach for the synthesis of agrochemicals and pharmaceuticals, as demonstrated by a four-step, telescoped synthesis of measles therapeutic, AS-136A, in a total
Fluoroalkyl-Substituted Diazomethanes and Their Application in a General Synthesis of Pyrazoles and Pyrazolines
作者:Lucas Mertens、Katharina J. Hock、Rene M. Koenigs
DOI:10.1002/chem.201601707
日期:2016.7.4
A novel continuous‐flow approach for the synthesis of fluoroalkyl‐substituted diazomethanes has been developed. Utilizing a cheap, self‐made microreactor fluoroalkyl‐substituted amines were transformed into the corresponding diazomethanes using tert‐butyl nitrite and acetic acid as catalyst. These diazomethanes were employed in [2+3] cycloaddition reactions with olefins and alkynes, yielding valuable
Direct [3+2]-cycloaddition of electron-deficient alkynes with CF3CHN2: Regioselective one-pot synthesis of 3-trifluoromethylpyrazoles
作者:Feng Li、Jingjing Wang、Wenlong Pei、Hong Li、Huiling Zhang、Manman Song、Linyun Guo、Anan Zhang、Lantao Liu
DOI:10.1016/j.tetlet.2017.09.086
日期:2017.11
of electron-deficient terminal alkynes with 2,2,2-trifluorodiazoethane under mild conditions to afford a series of 5-substituted 3-trifluoromethylpyrazoles in highyields is described. The potential application of this cycloaddition reaction was demonstrated via the efficient synthesis of a key intermediate of the antiviral drug AS-136A and a fluorinated analog of Tebufenpyrad.