Enantioselective Syntheses of Furan Atropisomers by an Oxidative Central-to-Axial Chirality Conversion Strategy.

For the first time, enantiomerically enriched atropoisomeric furans have been accessed using a central-to-axial chirality conversion strategy. Hence, oxidation of the enantioenriched dihydrofuran precursors gave rise to axially chiral furans with high enantiopurities accounting from excellent conversion percentages (cp) in most cases.

Photocatalytic dehydrative etherification of alcohols with a nanoporous gold catalyst.

A simple and efficient photocatalytic approach for dehydrative etherification of alcohols has been developed by a nanoporous gold catalyst. This protocol features no requirement of addition of acids or bases, broad substrate generality, and excellent acid-sensitive functional group tolerance. The mechanistic studies demonstrate the heterogeneous nature of the catalytic system and the recyclability of the catalyst was demonstrated repeatedly.

Gold(I)-catalyzed unprecedented rearrangement reaction between 2-aminobenzaldehydes with propargyl amines: an expedient route to 3-aminoquinolines.

Access to aminoquinolines: a gold(I)-catalyzed unprecedented rearrangement reaction between 2-aminobenzaldehydes with propargyl amine was studied. The study provided, for the first time, direct access to 3-aminoquinolines in one step starting from readily available starting materials. Elegantly designed experiments were employed to unravel the mechanism of this unprecedented rearrangement, which are corroborated by DFT calculations.

Cooperative catalysis with metal and secondary amine: synthesis of 2-substituted quinolines via addition/cycloisomerization cascade.

A cooperative catalytic system, consisting of CuI and pyrrolidine, has been developed for an efficient synthesis of 2-substituted quinolines. A combination of both the catalysts is necessary; the use of either catalyst alone does not give the product.

Gold- and platinum-catalyzed formal Markownikoff's double hydroamination of alkynes: a rapid access to tetrahydroquinazolinones and angularly-fused analogues thereof.

A highly efficient gold(I)- and platinum(II)-catalyzed process for formal Markownikoff's double hydroamination of alkynes tethered with hydroxyl group has been developed. The method was shown to be applicable to a broad range of 2-aminobenzamides and alkynols leading to the formation of multiply substituted tetrahydroquinazolinones. Interestingly, when Pt(IV)Cl(4) catalyst was employed, cyclic angularly fused compound was obtained.

Platinum-catalyzed formal Markownikoff's hydroamination/hydroarylation cascade of terminal alkynes assisted by tethered hydroxyl groups.

An efficient method for Markownikoff's hydroamination-hydroarylation of alkynols using PtBr(2) as catalyst has been developed. The platinum-catalyzed reactions of alkynols with amino group containing aromatics were achieved in methanol over a reaction time of 6-24 h and temperature ranging from rt to 80 degrees C. This method works well for a variety of alkynols and aromatic amino compounds to give substituted pyrrolo[1,2-a]quinoxalines and indolo[3,2-c]quinolines in good to excellent yields.

The 5-HT3 receptor antagonist, ondansetron, blocks the development and expression of ethanol-induced locomotor sensitization in mice.

Manipulation of the serotonergic system has been shown to alter ethanol sensitization. Ondansetron is a 5-HT3 receptor antagonist, reported to attenuate cocaine and methamphetamine-induced behavioral sensitization, but no reports are available on its role in ethanol-induced behavioral sensitization. Therefore, an attempt has been made to assess this issue by using an earlier used animal model of ethanol-induced locomotor sensitization. Results indicated that ondansetron (0.25-1.0 mg/kg, subcutaneously) given before the challenge dose of ethanol (2.4 g/kg, intraperitoneally) injection, significantly and dose dependently attenuated the expression of sensitization. In addition, ondansetron (1.0 mg/kg, subcutaneously) given before ethanol injection on days 1, 4, 7, and 10 significantly blocked the development (days 1, 4, 7, and 10), and expression (day 15) of sensitization to the locomotor stimulant effect of ethanol injection. Ondansetron had no effect per se on locomotor activity and did not affect blood ethanol levels. Therefore, the results raise the possibility that ondansetron blocked the development and expression of ethanol-induced locomotor sensitization by acting on 5-HT3 receptors.

Enantioselective cooperative triple catalysis: unique roles of Au(I)/amine/chiral Brønsted acid catalysts in the addition/cycloisomerization/transfer hydrogenation cascade.

An enantioselective cooperative process involving the concerted/simultaneous action of three different catalysts i.e. Au(I)/amine/chiral Brønsted acid catalysts has been realized for the synthesis of 2-substituted tetrahydroquinolines from 2-aminobenzaldehydes and terminal alkynes.