C4-Alkylamination of C4-Halo-1 H-1-tritylpyrazoles Using Pd(dba)2 or CuI

Yoshihide Usami; Yuya Tatsui; Hiroki Yoneyama; Shinya Harusawa

doi:10.3390/molecules25204634

C4-Alkylamination of C4-Halo-1 H-1-tritylpyrazoles Using Pd(dba)₂ or CuI

Molecules. 2020 Oct 12;25(20):4634. doi: 10.3390/molecules25204634.

Authors

Yoshihide Usami¹, Yuya Tatsui¹, Hiroki Yoneyama¹, Shinya Harusawa¹

Affiliation

¹ Department of Pharmaceutical Organic Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.

Abstract

Alkylamino coupling reactions at the C4 positions of 4-halo-1H-1-tritylpyrazoles were investigated using palladium or copper catalysts. The Pd(dba)₂ catalyzed C-N coupling reaction of aryl- or alkylamines, lacking a β-hydrogen atom, proceeded smoothly using ^tBuDavePhos as a ligand. As a substrate, 4-Bromo-1-tritylpyrazole was more effective than 4-iodo or chloro-1-tritylpyrazoles. Meanwhile, the CuI mediated C-N coupling reactions of 4-iodo-1H-1-tritylpyrazole were effective for alkylamines possessing a β-hydrogen atom.

Keywords: 4-halopyrazole; Buchwald-Hartwig coupling; CuI mediated coupling; Pd(dba)2; aliphatic amine; amination.

MeSH terms

Catalysis
Copper / chemistry*
Palladium / chemistry*
Pyrazoles / chemistry*

Substances

Pyrazoles
Palladium
Copper