Access to 3‐Methyl‐4‐methylene‐N‐tosylpyrrolidine and 3,4‐DimethylN‐tosylpyrroline by Ruthenium‐Catalyzed Cascade Cycloisomerization/Isomerization Reactions

Abstract

New RuCl2(benzimidazole)(arene) complexes have been prepared. Upon reaction with 1,1‐diphenylprop‐2‐ynol they generate catalyst precursors which perform the cycloisomerization of diallyltosylamide into 3‐methyl‐4‐methylene‐N‐tosylpyrrolidine. The presence of N‐(2,4,6‐trimethylbenzyl)benzimidazole as ligand leads to a subsequent isomerization and gives the 3,4‐dimethyl‐N‐tosylpyrroline. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Metal Vinylidenes and Allenylidenes in Catalysis: Applications in Anti‐Markovnikov Additions to Terminal Alkynes and Alkene Metathesis

“…The nature of the substrate and the solvent influence both activity and selectivity, but the activity is always lower than that with nonchelating arene complexes. However, the allenylidene complexes generated in situ from benzimidazole-ruthenium(ii) precursors and propargylic alcohol in the presence of AgOTf selectively lead to cycloisomerization of 1,6-dienes (Scheme 71); [280] formation of the a-methylene pyrrolidine or the pyrroline derivative is very strongly dependent on the nature of the benzimidazole ligand. Thus, complexes XVIII a, b selectively afford the …”

Ruthenium(II) half-sandwich complexes containing thioamides: Synthesis, structures and catalytic transfer hydrogenation of ketones

“…Several viable methodologies have been established for this purpose, and most of them make use of a metal, in either stoichiometric or catalytic amounts, to promote the reaction between the reducing agent and the substrate. Transfer hydrogenation is arguably one of the most researched areas in homogeneous catalysis [29,30]. Catalytic transfer hydrogenation of ketones is a fundamental and key process for the production of a wide range of alcohols including chiral compounds, which are valuable final products and precursors for the pharmaceutical, agrochemical, flavor, fragrance, materials, and fine chemical industries [31e37].…”

New palladium(II)–N‐heterocyclic carbene complexes containing benzimidazole‐2‐ylidene ligand derived from menthol: synthesis, characterization and catalytic activities

“…The synthetic route for the menthol‐based 5,6‐(dimethyl)benzimidazolium salts is shown in . The chiral salts 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h are classic NHC precursors and were synthesized in approximately quantitative yield by quaternization of 1‐alkylbenzimidazole in PhMe with (+)‐chloromethylisomenthyl ether, starting from a commercially available chiral alkyl chloride at room temperature . The salts 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h were characterized from their spectroscopic data and elemental analyses.…”

“…The acetate‐bridged palladium dimer [Pd(μ‐OAc)(ppy)] 2 (ppy = 2‐phenylpyridine) was prepared according to the literature . 2,4,6‐Trimethyl bromide, 2,3,5,6‐tetramethylbenzyl bromide, 2,3,4,5,6‐pentamethylbenzyl bromide and 1‐substituted 5,6‐(dimethyl)benzimidazoles were prepared according to a slightly modified procedure from the literature . Other general experimental conditions and spectral data can be found in the supporting information.…”