RESUMEN
An unprecedented enantioselective synthesis of spiro-γ-lactams via a sequential C-H olefination/asymmetric [4+1] spirocyclization under a simple CoII /chiral spiro phosphoric acid (SPA) binary system is reported. A range of biologically important spiro-γ-lactams are obtained with high levels of enantioselectivity (up to 98 % ee). The concise, asymmetric synthesis of an aldose reductase inhibitor was successfully achieved. Notably, contrast to previous reports that relied on the use of cyclopentadienyl or its derivatives (achiral Cp*, CptBu , or chiral Cpx ) ligated CoIII complexes requiring tedious steps to prepare, cheap and commercially available cobalt(II) acetate tetrahydrate was used as an efficient precatalyst.
RESUMEN
An unprecedented synthesis of valuable benzofuran-3(2 H)-one scaffolds with a quaternary center was developed via Rh/Co relay catalyzed C-H functionalization/annulation of N-aryloxyacetamides with propiolic acids in moderate to good yields. The reaction features the simultaneous construction of the benzofuran motif containing a C2 quaternary center and a C3 carbonyl group. The preliminary mechanism study verified that the O atom of C3 carbonyl group originates from molecular oxygen.
RESUMEN
An efficient synthesis of thiazolidine-2,4,5-triimine derivatives was developed via Ni-catalyzed oxidative double isocyanide insertion to thioureas under air conditions, in which thioureas play three roles as a substrate, a ligand, and overcoming isocyanide polymerization. The reaction is featured by employing a low-cost and low loading Ni(acac)2 catalyst, without any additives, and high atom economy. This is the first example to directly apply a Ni(II) catalyst in oxidative double isocyanide insertion reactions.
RESUMEN
A new CuI/1,10-phen-catalyzed reaction for the synthesis of 3-ylideneoxindoles from readily available isatins and ethyl isocyanoacetate, in which ethyl isocyanoacetate acts as a latent two-carbon donor like the Wittig reagent, is reported. A tandem procedure including 1,3-dipolar cycloaddition/inverse 1,3-dipolar ring opening/olefination allows the preparation of 3-ylideneoxindoles with broad functional group tolerance.
RESUMEN
A concise and direct synthetic strategy for the construction of 2-aryliminochromene skeleton by cascade three-component coupling reaction of arynes, N,S-keteneacetals, and DMF in good yields has been disclosed. The process demonstrates the first example of aryne chemistry combined with N,S-keteneacetals. Using this strategy, an expeditious synthesis of biologically important arylimino-2H-chromene-3- carboxamides was achieved.
RESUMEN
A facile and efficient method for the chemoselective synthesis of benzo[e]pyrazolo[1,5-c][1,3]thiazine derivatives has been developed by tandem Ullmann coupling reactions of ß-oxodithioesters (ODEs) with 3-(2-bromoaryl)-1H-pyrazoles in C-S bond formation manner, in which ODEs play dual roles as both a substrate and a ligand. A series of benzo[e]pyrazolo[1,5-c][1,3]thiazine derivatives were provided in good to excellent yields with CuI as the copper source in the presence of NaOH in CH3CN at 80 °C under a N2 atmosphere.
Asunto(s)
Cobre/química , Pirazoles/síntesis química , Compuestos de Sulfhidrilo/química , Tiazinas/síntesis química , Catálisis , Estructura Molecular , Pirazoles/química , Tiazinas/químicaRESUMEN
Highly substituted cyclopentenes can be accessed rapidly from isocyanides, aldehydes and malononitrile or ethyl cyanoacetate (AB2C2) using DABCO as a catalyst under solvent-free conditions at 40 °C within 30 min.