Synthesis of triphenylpyridines via an oxidative cyclization reaction using Sr-doped LaCoO3 perovskite as a recyclable heterogeneous catalyst.

Thu N M Le,Phuc H Pham,Tung T Nguyen,Tien V Huynh,Tien T T Tran,Khang H Trinh,Nam T S Phan,Minh-Vien Le,Son H Doan

doi:10.1039/c9ra04096j

Thu N M Le, Phuc H Pham + Show 7 more

Open Access

https://doi.org/10.1039/c9ra04096j

Copy DOI

Abstract

An La0.6Sr0.4CoO3 strontium-doped lanthanum cobaltite perovskite was prepared via a gelation and calcination approach and used as a heterogeneous catalyst for the synthesis of triphenylpyridines via the cyclization reaction between ketoximes and phenylacetic acids. The transformation proceeded via the oxidative functionalization of the sp3 C–H bond in phenylacetic acid. The La0.6Sr0.4CoO3 catalyst demonstrated a superior performance to that of the pristine LaCoCO3 as well as a series of homogeneous and heterogeneous catalysts. Furthermore, the La0.6Sr0.4CoO3 catalyst was facilely recovered and reused without considerable decline in its catalytic efficiency. To the best of our knowledge, the combination of ketoximes with easily available phenylacetic acids is novel.

Highlights

Functionalized pyridines have emerged as a precious class of privileged N-heterocyclic compounds, existing in a wide range of biologically active natural products, medicinal chemicals, agricultural chemicals, and functional organic materials.[1,2,3,4] Among the numerous pyridines, 2,4,6-triphenylpyridines offer important applications, and the development of effective synthetic approaches for these structures has been considered as a hot topic
We report the utilization of a strontium-doped lanthanum cobaltite perovskite as a recyclable heterogeneous catalyst for the synthesis of triphenylpyridines via oxidative cyclization reaction between ketoximes and phenylacetic acids (Scheme 1b)
The strontium-doped lanthanum cobaltite perovskite was used as a heterogeneous catalyst for the synthesis of 2,4,6-triphenylpyridine via the oxidative cyclization reaction between acetophenone oxime acetate and phenylacetic acid (Scheme 1b)

Summary

Introduction

Functionalized pyridines have emerged as a precious class of privileged N-heterocyclic compounds, existing in a wide range of biologically active natural products, medicinal chemicals, agricultural chemicals, and functional organic materials.[1,2,3,4] Among the numerous pyridines, 2,4,6-triphenylpyridines offer important applications, and the development of effective synthetic approaches for these structures has been considered as a hot topic. The utilization of available phenylacetic acids as green starting materials for organic synthesis via the oxidative functionalization of sp[3] C–H bonds has gained considerable attention.[37,38,39] In this work, we report the utilization of a strontium-doped lanthanum cobaltite perovskite as a recyclable heterogeneous catalyst for the synthesis of triphenylpyridines via oxidative cyclization reaction between ketoximes and phenylacetic acids (Scheme 1b). To the best of our knowledge, the oxidative cyclization between ketoximes and phenylacetic acids has not been previously mentioned in any literature

Experimental

Results and discussion

Conclusions