Phosphino-amine (PN) Ligands for Rapid Catalyst Discovery in Ruthenium-Catalyzed Hydrogen-Borrowing Alkylation of Anilines: A Proof of Principle

Role of ancillary ligands in selectivity towards acceptorless dehydrogenation versus dehydrogenative coupling of alcohols and amines catalyzed by cationic ruthenium(II)-CNC pincer complexes

An unexpected reversal in catalytic activity for acceptorless dehydrogenative coupling compared to acceptorless alcohol dehydrogenation has been observed using a series of cationic Ru(II)-CNC pincer complexes with different ancillary ligands. In continuation of our study of cationic Ru(II)-CNC pincer complexes 1a-6a, new complexes with bulky N-wingtips [Ru(CNCiPr)(CO)(PPh3)Br]PF6 (1b), [Ru(CNCCy)(CO)(PPh3)Cl]PF6 (1c), [Ru(CNCCy)(CO)(PPh3)H]PF6 (2c), [Ru(CNCiPr)(PPh3)2Cl]PF6 (3b), [Ru(CNCCy)(PPh3)2Cl]PF6 (3c), [Ru(CNCiPr)(PPh3)2H]PF6 (4b), [Ru(CNCCy)(PPh3)2H]PF6 (4c), [Ru(CNCiPr)(DMSO)2Cl]PF6 (6b), and [Ru(CNCCy)(DMSO)2Cl]PF6 (6c) [CNCR = 2,6-bis(1-alkylimidazol-2-ylidene)-pyridine] have been synthesized and the catalytic activities of the new complexes have been compared with their N-methyl analogues for transfer hydrogenation of cyclohexanone and acceptorless dehydrogenation of benzyl alcohol. Furthermore, all complexes have been utilized as catalysts in the dehydrogenative coupling reaction of benzyl alcohol with amines. While the catalytic activities of the new complexes for transfer hydrogenation and acceptorless alcohol dehydrogenation were found to be in line with the previously observed trend based on the ancillary ligands (CO > COD > DMSO > PPh3), for the acceptorless dehydrogenative coupling reaction, complexes containing PPh3 and DMSO ligands performed better compared to complexes containing CO and COD ligands. Based on NMR and mass investigation of catalytic reactions, a plausible mechanism has been suggested to explain the difference in catalytic activity and its reversal during the dehydrogenative coupling reaction. Furthermore, the substrate scope for the dehydrogenative coupling reaction of benzyl alcohol with a wide range of amines has been explored, including synthesizing some pharmaceutically important imines. All new complexes have been characterized by various spectroscopic techniques, and the structures of 4b and 6b have been confirmed by the single-crystal X-ray diffraction technique.

Electrochemical Oxidative N-H/P-H Cross-Coupling with H2 Evolution towards the Synthesis of Tertiary Phosphines

Tertiary phosphines(iii) find widespread use in many aspects of synthetic organic chemistry. Herein, we developed a facile and novel electrochemical oxidative N–H/P–H cross-coupling method, leading to a series of expected tertiary phosphines(iii) under mild conditions with excellent yields. It is worth noting that this electrochemical protocol features very good reaction selectivity, where only a 1 : 1 ratio of amine and phosphine was required in the reaction. Moreover, this electrochemical protocol proved to be practical and scalable. Mechanistic insights suggested that the P radical was involved in this reaction.

A facile and novel electrochemical oxidative N–H/P–H cross-coupling method for obtaining tertiary phosphines(iii) was developed.

Half-sandwich Ru(ii) arene complexes bearing benzimidazole ligands for the N-alkylation reaction of aniline with alcohols in a solvent-free medium

In this article, the direct N-alkylation reactions of amines with alcohol derivatives using the borrowing hydrogen methodology have been investigated.

Scalable Synthesis of Functionalized Ferrocenyl Azides and Amines Enabled by Flow Chemistry

A scalable access to functionalized ferrocenyl azides has been realized in flow. By halogen-lithium exchange of ferrocenyl halides and trapping with tosyl azide, a variety of functionalized ferrocenyl azides were obtained in high yields. To allow a scalable preparation of these potentially explosive compounds, a flow protocol was developed accelerating the reaction time to minutes and circumventing accumulation of potentially hazardous intermediates. The corresponding ferrocenyl amines were then prepared by a reliable reduction process.

Ruthenium-catalyzed synthesis of N-substituted lactams by acceptorless dehydrogenative coupling of diols with primary amines

Herein, we report the first example of synthesis of N-substituted lactams via an acceptorless dehydrogenative coupling of diols with primary amines in one step, which was enabled by combining Ru3(CO)12 with a hybrid N-heterocyclic carbene-phosphine-phosphine ligand as the catalyst.

Reaction of an arsinoamide with chloro tetrylenes: substitution and As-N bond insertion

Reaction of the arsinoamide [(Mes₂AsNPh){Li(OEt₂)₂}] with the low-valent group 14 compounds, [{PhC(^tBuN)₂}ECl] (E = Si, Ge) and GeCl₂·dioxane, resulted in two different reaction pathways: simple substitution or substitution accompanied by an insertion step. As a result, either insertion products with an As-Si[double bond, length as m-dash]N unit and an As-Ge bond, or substitution products, in which the intact arsinoamide binds to the group 14 elements via the N atom, were obtained.

A pincer ligand enabled ruthenium catalyzed highly selective N-monomethylation of nitroarenes with methanol as the C1 source

A straightforward and highly selective N-monomethylation of nitroarenes with methanol as the C1 source was developed.

Synthesis, characterization, and application of palladium complexes containing bis(aminophosphine) ligands

Two palladium complexes containing bis(aminophosphine) ligands have been prepared and characterized. Their solid structures were determined by X-ray single crystal diffraction studies. They were successfully employed in the Suzuki coupling reactions of phenylboronic acid and various aryl chlorides.

Aminophosphine ligands as a privileged platform for development of antitumoral ruthenium(ii) arene complexes

The potential utility of aminophosphine ligands in both high-throughput testing and rational design of new anticancer metallodrugs.

Ruthenium-catalyzed synthesis of tri-substituted 1,3,5-triazines from alcohols and biguanides

An efficient method for the synthesis of tri-substituted 1,3,5-triazine derivatives based on Ru-catalyzed reaction of alcohols with biguanides is presented.