Copper‐Catalyzed Synthesis of 5‐Aryl‐6‐(Trifluoromethyl)‐2, 3‐Dihydropyrazolo[1, 2‐a]Pyrazol‐1(5H)‐One. Issue 18 (10th August 2021)

• Record Type: Journal Article
• Authors: Zhang, Xinyu; Wang, Hui; Xie, Lili; You, Chenhui; Han, Xiaoyan; Weng, Zhiqiang
• Is Part Of: Chemistry, an Asian journal. Volume 16:Issue 18(2021)
• Page Start: 2669
• Page End: 2673
• Publication Date: 2021-08-10
• Subjects: [3+2]-cycloaddition -- azomethine imine -- trifluoromethylation -- pyrazole -- copper; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.202100693
• Languages: English
• ISSNs: 1861-4728

Abstract

Abstract: An efficient protocol for the synthesis of 5‐aryl‐6‐(trifluoromethyl)‐2, 3‐dihydropyrazolo[1, 2‐ a ]pyrazol‐1(5 H )‐one derivatives through a copper‐catalyzed [3+2]‐cycloaddition of azomethine imines with 3, 3, 3‐trifluoropropyne (generated in situ from dehydrobromination of 2‐bromo‐3, 3, 3‐trifluoropropene under base conditions) is developed. The advantages of this transformation are the broad substrate scope and the good functional group compatibility. The subsequent oxidation and nucleophilic substitution/aromatization provide a new approach to 4‐trifluoromethylated pyrazol‐1‐yl propanoic acids. Abstract : [3+2]‐Cycloaddition of azomethine imines with 3, 3, 3‐trifluoropropyne catalyzed by copper is achieved for the convenient access of 5‐aryl‐6‐(trifluoromethyl)‐2, 3‐dihydropyrazolo[1, 2‐ a ]pyrazol‐1(5 H )‐one. The consecutive oxidation and nucleophilic substitution/aromatization of these trifluoromethyl substituted N, N ‐bicyclic pyrazolidinones give 4‐trifluoromethylated pyrazol‐1‐yl propanoic acids.