Synthesis of C4-alkynylisoxazoles via a Pd-catalyzed Sonogashira cross-coupling reaction

Wen Yang; Yongqi Yao; Xin Yang; Yingying Deng; Qifu Lin; Dingqiao Yang

doi:10.1039/c9ra00577c

Synthesis of C4-alkynylisoxazoles via a Pd-catalyzed Sonogashira cross-coupling reaction

RSC Adv. 2019 Mar 18;9(16):8894-8904. doi: 10.1039/c9ra00577c. eCollection 2019 Mar 15.

Authors

Wen Yang¹, Yongqi Yao¹, Xin Yang¹, Yingying Deng¹, Qifu Lin¹, Dingqiao Yang¹

Affiliation

¹ Key Laboratory of Theoretical Chemistry of Environment, Ministry of Education, School of Chemistry and Environment, South China Normal University Guangzhou 510006 People's Republic of China yangdq@scnu.edu.cn.

Abstract

A Pd-catalyzed Sonogashira cross-coupling reaction for the synthesis of C4-alkynylisoxazoles from 3,5-disubsitituted-4-iodoisoxazoles and terminal alkynes was described, which could afford the corresponding products with high yield (up to 98%). The results indicated that the steric effect from the group at the C3 position of the isoxazole had greater influence on the cross-coupling reaction than that from the group at the C5 position. In addition, the group at the C3 position of the isoxazole showed negligible electronic effects on the cross-coupling reaction. Furthermore, a gram-scale reaction of the Sonogashira coupling reaction was also investigated. Finally, a plausible mechanism for the Sonogashira coupling reaction was proposed.