Nitrogen ligand influence on the CO-assisted ruthenium-catalyzed reductive amination

A representative set of amines and N-heterocycles was applied as additives in the CO-assisted Ru-catalyzed reductive amination of p-anisaldehyde with p-anisidine. Among the tested ligands, pyridine caused a strong activation for low active aliphatic substrates while bidentate heterocyclic ligands possess significant inhibition of catalyst for the majority of substrates.     

Alkyl formates as reagents for reductive amination of carbonyl compounds

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Diastereoselective reductive amination of pyrazolidinyl alkyl ketones

Reductive amination of pyrazolidinyl alkyl ketones with sodium triacetoxyborohydride or sodium tripivaloyloxyborohydride takes place diastereoselectively with the formation of aminoalkylpyrazolidines of trans structure. The volume of the substituent in the borohydrides does not affect the ratio of stereoisomers. Dedicated to the memory of A. A. Potekhin, renowned teacher, scientist, and editor of journal “Chemistry of Heterocyclic Compounds” __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 691–698, May, 2008.     

Synthesis of hydroquinone-, biphenol-, and binaphthol-containing aza macroheterocycles via regioselective hydroformylation and reductive amination

Rhodium(I) catalyzed regioselective hydroformylation of diolefins and subsequent reductive amination of the dialdehydes in the presence of α,ω-diamines is applied to azamacroheterocyclic ring synthesis. Starting from aromatic diallyl ethers of hydroquinone, biphenol and binaphthol 20-28 membered macroheterocycles were obtained in up to 78% yield.     

Reductive Amination of Aldehydes and Ketones with Primary Amines by Using Lithium Amidoborane as Reducing Reagent

A variety of secondary amines were obtained in high isolated yields in the reductive amination of aldehydes and ketones by using lithium amidoborane as reducing agent. Compared to ammonia borane, lithium amidoborane has higher reducibility, and thus, exhibits faster reaction rate.     

Coadsorption of carbon monoxide and copper atoms on rhodium electroplates

The partial removal of copper atoms from a preliminarily formed Cu_ad layer and the adsorption of Cu²⁺ cations in the presence of a CO_ads monolayer were demonstrated for Rh/Pt electrodes by means of transients of current and potentiodynamic and analytical measurements. The electrooxidation of the mixed CO_ads + Cu_ad layer in the course of anodic potential scans is shown to be accompanied by simultaneous removal of both species in a wide potentials range.Translated from Elektrokhimiya, Vol. 41, No. 3, 2005, pp. 367–370.Original Russian Text Copyright © 2005 by Gladysheva, Podlovchenko.     

Palladium on activated carbon catalyzed reductive amination of aldehydes and ketones by triethylsilane

Various aldehydes and ketones were efficiently transformed into the corresponding amines using amine derivatives in the presence of triethylsilane and a catalytic amount of palladium on activated carbon in ethanol. The proposed method provides a one‐pot synthesis of various amines in excellent yields after short reaction times. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis of catalytically active diene and cyclopentadienyl rhodium halide complexes

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Selective hydrosilylation of 1-alkynes with alkylsilanes catalyzed by rhodium in a carbon monoxide atmosphere

Hydrosilylation of 1-alkynes with PhMeSiH₂ andPh₂SiH₂ catalyzed by a highly active rhodiumspecies, generated in situ from rhodium under an atmospheric ofcarbon monoxide gave only (E)-vinylsilanes in excellent yield(>90%). In the absence of carbon monoxide, no reaction wasobserved under the same reaction conditions. Our Rh/CO catalytic systemleads to the (E)-stereoselectivity exclusively, while theRh₄(CO)₁₂ complex system produces only isomericproducts.     

Effective reductive amination of carbonyl compounds with hydrogen catalyzed by iridium complex in organic solvent and in ionic liquid

The direct reductive amination (DRA) of carbonyl compounds with amines has been achieved using homogenous iridium catalyst and gaseous hydrogen. It appeared that the cationic iridium catalyst, [Ir(cod)₂]BF₄, without any other ligands was sufficient for the reaction. For the DRA of the ketone substrates, an ionic liquid, [Bmim]BF₄, was found to be superior to the other organic solvent used. Especially, the counter anion of the ionic liquid has a significant influence on the selectivity, and at the same time, a high reaction temperature was found to be crucial for the excellent selectivity.     

Asymmetric Reductive Amination in Organocatalysis and Biocatalysis

This review summarizes the recent progress of organocatalytic and biocatalytic asymmetric reductive amination (ARA), a challenging but important topic for drug discovery and the pharmaceutical industry. At present, ARA can be divided into three categories: metal catalysis, organic catalysis, and biocatalysis. In the past decade, transition metal-catalysed ARA has been well established. Organocatalytic ARA has emerged as a powerful alternative to metal-catalysed ARA, the hydrogen sources used in organocatalytic ARA are usually Hantzsch esters, benzothiazolines, boranes, and hydrosilanes, which require Lewis base or phosphoric acid catalysts to activate them to give secondary chiral amines. It is worth mentioning that biocatalytic ARA has made remarkable progress in the last decade, amino acid dehydrogenases, amine dehydrogenases, opine dehydrogenases and imine reductases have been successfully used in ARA.     

Rhodium-catalyzed highly selective thioformylation of acetylenes with thiols and carbon monoxide

Highly regioselective thioformylation of terminal acetylenes with thiols and carbon monoxide has been developed by the use of rhodium(I) complexes as the catalyst: formyl and thio groups are introduced into the terminal and inner positions of acetylenes, respectively. The thioformylation is performed in the presence of a catalytic amount of rhodium(I) complexes, such as RhH(CO)(PPh₃)₃, RhCl(PPh₃)₃, and RhCl(CO)(PPh₃)₂, under the pressure of CO (3 MPa) at 120°C in CH₃CN to provide β-thio-α,β-unsaturated aldehydes in good yields. This thioformylation can be applied to a variety of terminal acetylenes and aromatic thiols. A mechanistic proposal includes the formation of the rhodium sulfide complex as the key species.     

Enantioselective hydrogenation in the presence of the rhodium(i) complex with (+)-4S,5S-N4,N4,N5,N5,2,2-hexamethyl-1,3-dioxolane-4,5-dimethaneamine

Hydrogenation of -acetamidocinnamic and itaconic acids and their esters was carried out in the presence of the cationic Rh^I triflate complex with (+)-4S,5S-N ⁴,N ⁴,N ⁵,N ⁵,2,2-hexamethyl-1,3-dioxolane-4,5-dimethaneamine (DIODMA). The optical yields depended on the nature of the solvent and the hydrogen pressure and reached 30%. The catalytically active forms of the complexes and their transformations in the presence of phosphines, molecular hydrogen, and the substrate were studied by ¹H and ³¹P NMR spectroscopy.     

Asymmetric Pd-catalyzed allylic amination of 1,3-diphenylallyl acetate with dipropylamine in ionic and molecular solvents

Asymmetric catalytic allylic amination of 1,3-diphenylallyl acetate with dipropylamine in an ionic liquid, 1-butyl-2,3-dimethylimidazolium tetrafluoroborate, and in THF and CH₂Cl₂ in the presence of palladium complexes of P-monodentate phosphite and phosphoramidite derivatives of S-1,1′-bis-2-naphthol was carried out. This gave a product with ee of up to 65%. The level of asymmetric induction is retained after three catalyst cycles. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2478–2481, November, 2005.     

Alternating copolymerization of propylene oxide with carbon monoxide catalyzed by Co complex and Co/Ru complexes

Co₂(CO)₈ catalyzes the ring‐opening copolymerization of propylene oxide with CO to afford the polyester in the presence of various amine cocatalysts. The ¹H and ¹³C{¹H} NMR spectra of the polyester, obtained by the Co₂(CO)₈–3‐hydroxypyridine catalyst, show the following structure ? [CH₂? CH(CH₃)? O? CO]_n? . The Co₂(CO)₈–phenol catalyst gives the polyester, which contains the partial structural unit formed through the ring‐opening copolymerization of tetrahydrofuran with CO. The bidentate amines, such as bipyridine and N,N,N′,N′‐tetramethylethylenediamine, enhance the Co complex‐catalyzed copolymerization, which produces the polyester with a regulated structure. Acylcobalt complexes, (RCO)Co(CO)_n (R = Me or CH₂Ph), prepared in situ, do not catalyze the copolymerization even in the presence of pyridine. This suggests that the chain growth involves the intermolecular nucleophilic addition of the OH group of the intermediate complex to the acyl–cobalt bond, forming an ester bond rather than the insertion of propylene oxide into the acyl–cobalt bond. Co₂(CO)₈? Ru₃(CO)₁₂ mixtures also bring about the copolymerization of propylene oxide with CO. The molar ratio of Ru to Co affects the yield, molecular weight, and structure of the produced copolymer. The catalysis is ascribed to the Ru? Co mixed‐metal cluster formed in the reaction mixture. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4530–4537, 2002     

Electrochemical generation of a nickel–carbonyl complex, catalyst for the electroreductive coupling of organic halides and carbon monoxide into ketones

The nickel–carbonyl complex Ni(CO)bpy is involved in the nickel-catalysed electroreductive coupling of organic halides and carbon monoxide into ketones. The active species is obtained from a stoichiometric mixture of Ni⁰, 2,2′-bipyridine and CO. The electrochemical method used to generate this complex allows a good tuning of Ni⁰ production versus CO dissolution. We have shown that Ni(CO)bpy results from a CO equilibrium exchange between Ni(CO)₂bpy and Nibpy.     

Direct reductive amination and selective 1,2-reduction of α,β-unsaturated aldehydes and ketones by NaBH4 using H3PW12O40 as catalyst

A simple and convenient procedure for direct reductive amination of aldehydes and ketones with sodium borohydride is described. The reaction has been carried out in methanol in the presence of a catalytic amount of H₃PW₁₂O₄₀ (0.5 mol %). α,β-Unsaturated aldehydes and ketones can be easily converted into the corresponding allyl alcohols by reaction with H₃PW₁₂O₄₀ (0.5 mol %)/NaBH₄.