The potential of copper(I)-zeolite catalysis was evaluated in the three-component KA 2 -coupling mediated synthesis of α-tertiary propargylamines. Our archetypal copper(I)-doped zeolite Cu I -USY proved to be efficient under ligand-and solvent-free conditions at 80 °C. Usable up to four times, this catalytic material enables the coupling of diverse ketones, alkynes, and amines with a broad functional group tolerance. A decarboxylative and a desilylative version, respectively, involving an alkynoic acid and trimethylsilylacetylene as alkyne surrogates, was also set up to bypass selectivity issues and/or to access α-tertiary propargylamines that are unattainable under standard KA 2 conditions. Interestingly, the KA 2 -type coupling reactions were successfully linked to other Cu I -catalyzed reactions, thus resulting in sequential one-pot processes under full Cu I -USY catalysis.
Direct conversion of methane to methanol (MTM) over Cu-zeolites is a so-called “dream reaction” for the chemical industry. There is still a lot that can be done in order to optimize the reaction by e.g. achieving a deeper understanding of the reaction mechanism and the nature of the Cu-sites. In this study, we investigated a solid-state ion exchange method to incorporate CuI ions into zeolites (MOR, BEA, ZSM-5 and FAU), as a more scalable technique. The solid-state ion exchange led to a Cu/Al ration of about 0.8, however with a heterogeneous distribution of Cu. Regardless, Fourier transform-infrared spectroscopy still revealed that most Brønsted acid sites were exchanged in all four samples. Further, CH4-temperature programmed reaction experiments showed that some Cu-sites formed were reactive towards CH4, with CuI-MOR and CuI-FAU having the largest CH4 consumption. Ultimately, the CuI-zeolites were tested in the MTM reaction and proved capable of producing methanol, even without the presence of Brønsted sites. A MOR with lower Cu/Al ratio (0.30) was also tested for comparison, and as this sample obtained a much higher productivity than the CuI-MOR with high Cu-loading (0.10 vs. 0.03 molMeOH/molCu), it was demonstrated that some fine-tuning is necessary to obtain the active Cu sites for methane activation.
The copper-zeolite catalysed three-component coupling reaction between an aldehyde or a ketone, a terminal ynamide and an amine is reported. The method, dubbed AYA (i.e. Aldehyde-Ynamide-Amine) and KYA (i.e. Ketone-Ynamide-Amine),...
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