Terminal Alkynes Hydroamination Catalyzed by Copper Nanoparticles

Abstract

The copper-catalyzed regioselective intermolecular hydroamination of terminal alkynes with amines has been accomplished. The reaction was effectively catalyzed by copper nanoparticles supported on montmorillonite K10 (CuNPs/MK10), and afforded the intended imines in good conversions. Then, imines were transformed into the corresponding amines after treatment with NaBH3CN. The catalyst could be recovered and reused in several cycles.

Copper Nanoparticles on Montmorillonite K-10: A Versatile Catalyst for the One-Pot Synthesis of 3,5-Disubstituted Isoxazoles Using Various Methodologies

“…The preparation and characterization of this catalyst (see experimental and Supporting Information) have been previously reported by some of us elsewhere. 19 The CuNPs/MK-10 catalyst consists of spherical CuNPs with a diameter of ca. 2.5 ± 1.5 nm (TEM, Supporting Information), highly dispersed on the support, and with a copper content of 1.7 wt % as determined by AAS and ICP/MS.…”

“…Column chromatography was performed with Merck silica gel 60 (0.040-0.063 mm, 240-400 mesh) and hexane/EtOAc as eluent. NMR spectra were recorded on a Bruker ARX-300 spectrometer (300 MHz for 1 H NMR, 75 MHz for 13 C NMR and 282 MHz for 19 F NMR). Chemical shifts () are reported in parts per million from tetramethylsilane using the residual solvent resonance (CDCl 3 : 7.26 ppm for 1 H NMR, 77.16 ppm for 13 C NMR).…”

“…Light yellow solid; mp 72-74 °C; R f = 0.57 (EtOAc/hexane, 1:4). (19). 27 Method A (42 mg, 37%) and method B (70 mg, 61%).…”