24070-10-8

Reactions of (2-(pyren-1-ylmethylene)hydrazinyl)benzothiazole (L) with ruthenium(II) prefabricated precursors [RuHCl(CO)(EPh3)3] and [RuH2(CO)(EPh3)3] (E = P or As) afforded new Ru(II) complexes [RuCl(CO)(EPh3)2(L)] and [RuH(CO)(EPh3)2(L)] (E = P or As) (1–4). All the Ru(II) complexes (1–4) were characterized by IR, NMR spectroscopies, ESI-mass spectrometry and elemental analyses. The solid-state structures of Ru(II) complexes (2 and 3) were established by single crystal X-ray analyses and revealed distorted octahedral geometries around the ruthenium(II) ion and mono anionic bidentate N^N coordination mode for hydrazine ligand. The Ru(II) complexes 2 and 3 were also analyzed using Hirshfeld surface analysis and DFT calculations. Moreover, all the complexes (1–4) were utilized in the N-alkylation reactions of amines using alcohol. Complex 3 was found to be highly active towards N-alkylation of different aromatic amines with alcohol.

We have established a method for the highly regio- and enantioselective functionalization of tert-butyl groups via intramolecular amide carbene insertion into C-H bonds, yielding γ-lactams with 91% ee in up to 99% yield. This reaction uses a ruthenium(II) phenyl oxazoline (Ru(II)-Pheox) complex. The catalytic intramolecular carbene transfer reaction to the primary C-H bond proceeds rapidly and selectively compared to that with secondary C-H, benzylic secondary C-H, tert-C-H, or sp2C-H bonds in the presence of 1 mol % Ru(II)-Pheox catalyst. This is the first example of a catalytic carbenoid insertion into an unactivated tert-butyl group with enantiocontrol at the carbenoid carbon.

A Smiles-type radical rearrangement induced by visible-light-mediated decarboxylation of w-aryl-N-(acyloxy)phthalimides was developed, giving rise to pharmacologically important substance classes: phenylethylamine derivatives, dihydroisoquinolinones, and

The first general protocol for the direct reductive N-functionalization of aliphatic nitro compounds is presented. The nitro group is partially reduced to a nitrenoid, with a mild and readily available combination of B2pin2 and zinc organyls. Thereby, the formation of an unstable nitroso intermediate is avoided, which has so far severely limited reductive transformations of aliphatic nitro compounds. The reaction is concluded by an electrophilic amination of zinc organyls.

An atom economical and catalytic route for the synthesis of aryl- and alkyl-substituted secondary amines has been developed. Using a bis(amidate)bis(amido)titanium(IV) precatalyst, the hydroamination of terminal alkynes with a range of amines results in the selective formation of the anti-Markovnikov product. The crude enamine/imine mixtures are effectively hydrogenated using palladium on carbon (Pd/C) and H2 to afford the corresponding secondary amine in excellent yields. Simple work-up procedures allow for the isolation of pure compounds while avoiding purification via column chromatography.

Carbene intermediates are very useful species for a range of reactions including C-H insertions and cycloadditions. They are most commonly generated by metal-catalyzed release of nitrogen gas from diazo precursors. Herein, we present a novel C-H insertion

A range of ruthenium-arene compounds with chloride, bromide or iodide ligands were prepared and tested as catalysts for the homogeneous redox neutral alkylation of tert-butylamine with phenethyl alcohol, and compared to the previously reported catalyst [R

A range of ruthenium-arene compounds with chloride, bromide or iodide ligands were prepared and tested as catalysts for the homogeneous redox neutral alkylation of tert-butylamine with phenethyl alcohol, and compared to the previously reported catalyst [R

The heavier group 2 complexes [M{N(SiMe3)2} 2]2(1, M = Ca; 2, M = Sr) and [M{CH(SiMe3) 2}2(THF)2] (3, M = Ca; 4, M = Sr) are shown to be effective precatalysts for the intermolecular hydroamination of vinyl arenes and dienes under mild conditions. Initial studies revealed that the amide precatalysts, 1 and 2, while compromised in terms of absolute activity by a tendency toward transaminative behavior, offer greater stability toward polymerization/oligomerization side reactions. In every case the strontium species, 2 and 4, were found to outperform their calcium congeners. Reactions of piperidine with para-substituted styrenes are indicative of rate-determining alkene insertion in the catalytic cycle while the ease of addition of secondary cyclic amines was found to be dependent on ring size and reasoned to be a consequence of varying amine nucleophilicity. Hydroamination of conjugated dienes yielded isomeric products via η3-allyl intermediates and their relative distributions were explained through stereoelectronic considerations. The ability to carry out the hydroamination of internal alkynes was found to be dramatically dependent upon the identity of the alkyne substituents while reactions employing terminal alkynes resulted in the precipitation of insoluble and unreactive group 2 acetylides. The rate law for styrene hydroamination with piperidine catalyzed by [Sr{N(SiMe3) 2}2]2 was deduced to be first order in [amine] and [alkene] and second order in [catalyst], while large kinetic isotope effects and group 2 element-dependent ΔS? values implicated the formation of an amine-assisted rate-determining alkene insertion transition state in which there is a considerable entropic advantage associated with use of the larger strontium center.

The alkylation of amines by alcohols has been achieved using 0.5 mol percent [Ru(p-cymene)CI2]2 with the bidentate phosphines dppf or DPEphos as the catalyst. Primary amines have been converted into secondary amines, and secondary amines into tertiary amines, including the syntheses of Piribedil, Tripelennamine, and Chlorpheniramine. A/-Heterocyclization reactions of primary amines are reported, as well as alkylation reactions of primary sulfonamides. Secondary alcohols requiremore forcing conditions than primary alcohols but are still effective a lkylating agents in the presence of this catalyst.

The conversion of primary amines into secondary amines has been achieved using alcohols as the alkylating agent, catalysed by [Ru(p-cymene)Cl 2]2 and a bidentate phosphine ligand. The Royal Society of Chemistry.

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Carboxylate and carboxamide ligands of dirhodium(II) catalysts control chemoselectivity in competitive metal carbene transformations of diazo compounds. For competitive intramolecular cyclopropanation versus intramolecular aromatic substitution with 1-diazo-3-aryl-5-hexen-2-ones, use of Rh2(OAc)4 results in the products from both transformations in nearly equal amounts, but dirhodium(II) perfluorobutyrate (Rh2(pfb)4) provides only the aromatic substitution product while dirhodium(II) caprolactamate (Rh2(cap)4) gives only the cyclopropanation product. Similar results are obtained from dirhodium(II) catalysts in competitive intramolecular cyclopropanation versus tertiary C-H insertion, aromatic cycloaddition versus C-H insertion, cyclopropanation versus aromatic cycloaddition, and C-H insertion versus aromatic substitution. The order of reactivity for metal carbenes generated from Rh2(pfb)4 is aromatic substitution > tertiary C-H insertion > cyclopropanation ～ aromatic cycloaddition > secondary C-H insertion, and the rate differences between them are as much as 100-fold. For Rh2(cap)4 the order of reactivity is cyclopropanation > tertiary C-H insertion > secondary C-H insertion > aromatic cycloaddition with aromatic substitution not observed as a competing process for the diazo compounds examined. Control of chemoselectivity through charge and/or frontier molecular orbital properties of the intermediate metal carbene has been evaluated. Competitive product formation from dirhodium(II) caprolactamate catalyzed reactions of N-tert-butyl-N-benzyldiazoacetoacetamide is temperature dependent over a narrow 15-deg range. The effect of carbene substituents other than the ligated dirhodium(II) on chemoselectivity is described and discussed.