ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Rhodium complexes catalyze oxidative coupling between salicylaldehyde and phenylacetylene via C–H bond activation

Hongge Jia, Yanan Tang, Yongqiang Shi, Liqun Ma, Zijian He, Weiwei Lai, Yi Yang, Yazhen Wang, Yu Zang, and Shuangping Xu

College of Materials Science and Engineering, Key Laboratory of Polymeric Composition and Modification, Qiqihar University, Qiqihar, China

E-mail: 1542151015@qq.com

Abstract: A coupling reaction between salicylaldehyde and phenylacetylene was catalyzed by well-defined rhodium complexes, Rh(cod)(l-amino acid) (cod is 1,5-cyclooctadiene; l-amino acid is l-proline, l-phenylalanine and l-valine), to give a flavonoid in 40–88% yield, providing a method for flavonoid synthesis. The coupling reactions catalyzed by Rh(cod)(l-amino acid)s gave higher yields than those by [Rh(cod)Cl]₂ without l-amino acid ligands. The reaction mechanism may be that l-amino acid ligands of the rhodium complexes can provide an empty track for phenylacetylene to form a ring structure that fractures to produce the aim flavonoid and Rh^IX species. Then, the active Rh^IX specie is oxidized to regenerate Rh^IIIX₃ by Cu(OAC)₂.

Keywords: Rhodium; Oxidation; Arene ligands; Carbonylation; Flavone

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-017-0153-4

Chemical Papers 71 (9) 1791–1795 (2017)