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• 17371-59-4 2-methyl-3-((2-methyl-1H-indol-3-yl)(phenyl)methyl)-1H-indole 

Relevant academic research and scientific papers

Asymmetric Transfer Hydrogenation of N-Unprotected Indoles with Ammonia Borane

A metal-free asymmetric transfer hydrogenation of unprotected indoles was successfully realized using a catalyst derived from HB(C6F5)2 and (S)-tert-butylsulfinamide with ammonia borane as a hydrogen source. A variety of indolines were achieved in 40-78percent yields with up to 90percent ee.

Method for synthesizing chiral indoline from 2, 3-disubstituted indole generated in situ through asymmetric hydrogenation of palladium

The invention discloses a method for synthesizing chiral indoline from 2, 3-disubstituted indole generated in situ through palladium-catalyzed asymmetric hydrogenation. The method comprises the following steps: by using a 1-5mol% palladium catalyst, adding 1-2.0 equev. of an acid, and carrying out asymmetric hydrogenation on the in-situ generated 2, 3-disubstituted indole compound to obtain the corresponding chiral indoline compound of which the enantiomeric excess can be up to 97% at most. The method is simple and convenient to operate, practical, easy to implement, high in yield, environmentally friendly, available in catalyst business and mild in reaction condition, and has potential practical application value.

Enantioselective hydrogenation of N-heteroaromatics catalyzed by chiral diphosphine modified binaphthyl palladium nanoparticles

The first application of binaphthyl-stabilized palladium nanoparticles (Bin-PdNPs) with chiral modifiers in asymmetric hydrogenation of N-heteroaromatics is revealed. With an appropriate ratio of R-BINAP/Bin-PdNPs used, the pre-prepared chiral nanocatalyst achieves asymmetric hydrogenations of 2-substituted quinolines with good to excellent yields and moderate enantioselectivities, which showed superior catalytic properties to the R-BINAP/Pd complex. Moreover, this protocol is also applicable to 2-substituted indoles.

Homogenous Pd-catalyzed asymmetric hydrogenation of unprotected indoles: Scope and mechanistic studies

An efficient palladium-catalyzed asymmetric hydrogenation of a variety of unprotected indoles has been developed that gives up to 98% ee using a strong Br?nsted acid as the activator. This methodology was applied in the facile synthesis of biologically active products containing a chiral indoline skeleton. The mechanism of Pd-catalyzed asymmetric hydrogenation was investigated as well. Isotope-labeling reactions and ESI-HRMS proved that an iminium salt formed by protonation of the C=C bond of indoles was the significant intermediate in this reaction. The important proposed active catalytic Pd-H species was observed with 1H NMR spectroscopy. It was found that proton exchange between the Pd-H active species and solvent trifluoroethanol (TFE) did not occur, although this proton exchange had been previously observed between metal hydrides and alcoholic solvents. Density functional theory calculations were also carried out to give further insight into the mechanism of Pd-catalyzed asymmetric hydrogenation of indoles. This combination of experimental and theoretical studies suggests that Pd-catalyzed hydrogenation goes through a stepwise outer-sphere and ionic hydrogenation mechanism. The activation of hydrogen gas is a heterolytic process assisted by trifluoroacetate of Pd complex via a six-membered-ring transition state. The reaction proceeds well in polar solvent TFE owing to its ability to stabilize the ionic intermediates in the Pd-H generation step. The strong Br?nsted acid activator can remarkably decrease the energy barrier for both Pd-H generation and hydrogenation. The high enantioselectivity arises from a hydrogen-bonding interaction between N-H of the iminium salt and oxygen of the coordinated trifluoroacetate in the eight-membered-ring transition state for hydride transfer, while the active chiral Pd complex is a typical bifunctional catalyst, effecting both the hydrogenation and hydrogen-bonding interaction between the iminium salt and the coordinated trifluoroacetate of Pd complex. Notably, the Pd-catalyzed asymmetric hydrogenation is relatively tolerant to oxygen, acid, and water.

Chiral 2,3-disubstituted indolines from indoles and aldehydes by organocatalyzed tandem synthesis involving reduction by trichlorosilane

The organocatalytic trichlorosilane reduction system has been successfully utilized to develop a multi-step tandem approach for the easy preparation of chiral 2-methyl-3-alkylindolines starting from simple 2-methylindoles and aldehydes. A broad range of c

Pd-Catalyzed asymmetric hydrogenation of 3-(toluenesulfonamidoalkyl)indoles

A series of 2-substituted 3-(toluenesulfonamidoalkyl)indoles was synthesized by application of (EtO)2POH or iodine as the catalyst, and was hydrogenated using chiral Pd catalyst, giving the 2,3-disubstituted indolines with up to 97% ee. The Royal Society of Chemistry 2012.

An enantioselective approach to 2,3-disubstituted indolines through consecutive Bronsted acid/Pd-complex-promoted tandem reactions

In tandem: A divergent and enantioselective approach to 2,3-disubstituted indolines was developed through consecutive Bronsted acid/Pd-complex- promoted tandem reactions from simple 2-substituted indoles and aldehydes in one operation to give up to 98 % ee (see scheme; R1=H, F, or Me; R 2=alkyl; R3=aryl or alkyl). Three Bronsted acid promoted steps and two Pd-catalyzed hydrogenation steps were involved in this process. Copyright

Direct asymmetric hydrosilylation of indoles: Combined Lewis base and bronsted acid activation

Quite a pair: The first organocatalytic direct asymmetric reduction of unprotected 1H-indoles to chiral indolines has been developed. The reaction proceeds through the generation of electrophilic indolenium ions by a Bronsted acid, and then chiral Lewis base (1) mediated enantioselective hydride transfer with HSiCl3. A variety of chiral indolines were obtained with moderate to excellent enantioselectivity. MOM=methoxymethyl. Copyright