thiourea and indole

An efficient organocatalyzed enantioselective hydrophosphinylation of indole-derived vinylogous imines generated

Topics: Catalysis; Imines; Indoles; Oxides; Quinine; Stereoisomerism; Thiourea

Four 2-(1H-indol-3-yl)ethylthiourea derivatives were prepared by condensation of 2-(1H-indol-3-yl)ethanamine with the corresponding aryl/alkylisothiocyanates in a medium-polarity solvent. Their structures were confirmed by spectral techniques, and the molecular structure of 3 was determined by X-ray crystal analysis. For all derivatives, the binding affinities at the 5-HT

Topics: Amphetamine; Analgesics; Animals; Anti-Inflammatory Agents, Non-Steroidal; Binding Sites; Crystallography, X-Ray; Dose-Response Relationship, Drug; Hyperkinesis; Indoles; Male; Mice; Models, Molecular; Molecular Structure; Receptors, Dopamine D2; Receptors, Serotonin, 5-HT1; Receptors, Serotonin, 5-HT2; Structure-Activity Relationship; Thiourea

We describe enantioselective syntheses of strychnos and chelidonium alkaloids. In the first case, indole acetic acid esters were established as excellent partner nucleophiles for enantioselective cooperative isothiourea/Pd catalyzed α-alkylation. This provides products containing indole-bearing stereocenters in high yield and with excellent levels of enantioinduction in a manner that is notably independent of the N-substituent. This led to concise syntheses of (-)-akuammicine and (-)-strychnine. In the second case, the poor performance of ortho-substituted cinnamyl electrophiles in the enantioselective cooperative isothiourea/Ir catalyzed α-alkylation was overcome by appropriate substituent choice, leading to enantioselective syntheses of (+)-chelidonine, (+)-norchelidonine, and (+)-chelamine.

Topics: Alkaloids; Alkylation; Benzophenanthridines; Berberine Alkaloids; Catalysis; Chelidonium; Humans; Indoles; Iridium; Palladium; Sirtuin 1; Stereoisomerism; Strychnine; Strychnos; Thiourea

The enantioselective transformations of indoles preferentially take place in the more-reactive azole ring. However, the methods for the enantioselective functionalization of the indole benzene ring are scarce. In this paper, a series of bifunctional (thio)urea derivatives were used to organocatalyze the enantioselective Friedel-Crafts hydroxyalkylation of indoles with isatins. The resulting products were obtained in good yields (65-90%) with up to 94% enantiomer excess (ee). The catalyst type and the substrate scope were broadened in this methodology.

Topics: Alkylation; Catalysis; Hydroxylation; Indoles; Isatin; Models, Molecular; Stereoisomerism; Thiourea; Urea

Small organic and metal-containing molecules (molecular mass <1,000) can catalyse synthetically useful reactions with the high levels of stereoselectivity typically associated with macromolecular enzymatic catalysts. Whereas enzymes are generally understood to accelerate reactions and impart selectivity as they stabilize specific transition structures through networks of cooperative interactions, enantioselectivity with chiral, small-molecule catalysts is rationalized typically by the steric destabilization of all but one dominant pathway. However, it is increasingly apparent that stabilizing effects also play an important role in small-molecule catalysis, although the mechanistic characterization of such systems is rare. Here, we show that arylpyrrolidino amido thiourea catalysts catalyse the enantioselective nucleophilic ring opening of episulfonium ions by indoles. Evidence is provided for the selective transition-state stabilization of the major pathway by the thiourea catalyst in the rate- and selectivity-determining step. Enantioselectivity is achieved through a network of attractive anion binding, cation-π and hydrogen-bond interactions between the catalyst and the reacting components in the transition-structure assembly.

Topics: Catalysis; Hydrogen Bonding; Indoles; Ions; Stereoisomerism; Sulfonium Compounds; Thiourea