Wang Huamin, Meng Li-Qin, Niu Wenjing, Yang Wan-Qi, Ou Yu, Lin Ying-Wu
School of Chemistry and Chemical Engineering, University of South China, Hengyang, P. R. China.
Laboratory of Protein Structure and Function, University of South China Medical School, Hengyang, P. R. China.
Chem Commun (Camb). 2024 Oct 22;60(85):12425-12428. doi: 10.1039/d4cc03826f.
A general and practical KCO-promoted [3+2] annulation between trifluoroacetaldehyde -triftosylhydrazone (TFHZ-Tfs) and 4-nitroisoxazoles has been developed to access structurally diverse trifluoromethylpyrazolo[3,4-]isoxazoles. Mechanistically, CFCHN is formed by TFHZ-Tfs decomposition and involves a formal [3+2] dearomative cycloaddition with 4-nitroisoxazoles, followed by aromatization the elimination of the nitro group. Furthermore, this protocol is metal-free, scalable, mild, and operationally safe, with a broad substrate scope and high functional group compatibility.
已开发出一种通用且实用的碳酸钾促进的三氟乙醛三氟甲磺酰腙（TFHZ-Tfs）与4-硝基异恶唑之间的[3+2]环化反应，以合成结构多样的三氟甲基吡唑并[3,4-b]异恶唑。从机理上讲，CFCHN由TFHZ-Tfs分解形成，涉及与4-硝基异恶唑的形式上的[3+2]去芳构化环加成反应，随后进行芳构化并消除硝基。此外，该方案无金属、可扩展、温和且操作安全，具有广泛的底物范围和高官能团兼容性。
