Iridium-Catalyzed Enantioselective Hydroarylation of Alkenes through C-H bond Activation: Experiment and Computation.

A new catalytic enantioselective hydroarylation of unactivated olefins is developed that provides rapid access to functionalized chiral dihydrobenzofurans with good yields and excellent enantioselectivities. Simple aromatic ketones or amides act as a directing group allowing the regioselective reaction at the more hindered ortho position. Tertiary benzylic stereocenters are obtained directly under mild reaction conditions and with complete atom economy from readily available starting materials.

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions.

The direct exploitation of 'electrons' as reagents in synthetic organic transformations is on the verge of a renaissance by virtue of its greenness, sustainability, atom economy, step economy and inherent safety. Achieving stereocontrol in such organic electrochemical reactions remains a major synthetic challenge and hence demands great expertise. This review provides a comprehensive discussion of the details of stereoselective organic electrochemical reactions along with the synthetic accomplishments achieved with these methods.

Robustness screen in enantioselective catalysis enabled generation of enantioenriched heterocyclic scaffolds in one pot.

Enantioselective catalysis has emerged as a powerful synthetic paradigm and has accelerated the development of new methods to make diverse chiral molecules. Generally, these reactions are very sensitive to the steric and electronic environment present in the catalyst as well as the substrates. With this scenario, the presence of an additional component in the reaction mixture is expected to add complexity in achieving the enantioselective variants. Herein, we report that various enantioenriched molecules could be obtained from multiple starting materials in one pot. The reaction of aminoaromatics A with alkynols B1, B2, B3…︁Bn with a Au(I)/chiral Brønsted acid catalyst afforded AB1*, AB2*, AB3*…ABn*; while, the reaction of alkynols B with aminoaromatics A1, A2, A3…An under the same reaction conditions gave A1B*, A2B*, A3B*…AnB*.

Gold(I)/chiral Brønsted acid catalyzed enantioselective hydroamination-hydroarylation of alkynes: the effect of a remote hydroxyl group on the reactivity and enantioselectivity.

The catalytic enantioselective hydroamination-hydroarylation of alkynes under the catalysis of (R3P)AuMe/(S)-3,3'-bis(2,4,6-triisopropylphenyl)-1,1'-binaphthyl-2,2'-diyl hydrogenphosphate ((S)-TRIP) is reported. The alkyne was reacted with a range of pyrrole-based aromatic amines to give pyrrole-embedded aza-heterocyclic scaffolds bearing a quaternary carbon center. The presence of a hydroxyl group in the alkyne tether turned out to be very crucial for obtaining products in high yields and enantioselectivities. The mechanism of enantioinduction was established by carefully performing experimental and computational studies.

Enantioselective cooperative catalysis.

In recent years, enantioselective cooperative catalytic reactions, wherein two catalysts work simultaneously to form products which cannot be obtained by the use of a single catalyst alone, have attracted considerable attention. This review focuses on this emerging field, with particular emphasis on mechanistic aspects, which will help readers to understand the role of each catalyst.

Electrochemical low valent cobalt-catalyzed addition of aryl and vinyl chlorides to α-ketoamides via C-Cl bond activation.

The development of an electrochemical cobalt catalyzed C-Cl bond activation at room temperature for the nucleophilic addition of aryl and vinyl chlorides to α-ketoamides is described. The overall method operates through an electrochemically induced low valent cobalt catalyst that oxidatively adds to aryl or vinyl chlorides affording medicinally important 3-hydroxy oxindole and 3-hydroxypyrrolidinone scaffolds. The development of an enantioselective version using a chiral pyrox ligand is also demonstrated.

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.

A one-pot catalysis: the strategic classification with some recent examples.

In this "Emerging Area", the strategic classification of one-pot catalysis, i.e. cooperative, relay and sequential catalysis, is described. In order to illustrate this classification, we take the readers through a series of recent examples which utilize either metal-metal, metal-organo and organo-organo catalysts. The compilation clearly demonstrates the explosive growth and power of this field, which has become, in the last few years, an important technique particularly in the case of enantioselective catalysis.

Pt(IV)-catalyzed hydroamination triggered cyclization: a strategy to fused pyrrolo[1,2-a]quinoxalines, indolo[1,2-a]quinoxalines, and indolo[3,2-c]quinolines.

A PtCl(4)-catalyzed hydroamination-triggered cyclization strategy to access biologically interesting N-containing heterocycles such as pyrrolo[1,2-a]quinoxalines, indolo[1,2-a]quinoxalines, and indolo[3,2-c]quinolines is described. The reaction makes use of aminoaromatics such as 1-(2-aminophenyl)pyrroles, N-(2-aminophenyl)indoles, 2-(2-aminophenyl)indoles, and alkynes having a tethered hydroxyl group. Mechanistically, the reaction is very appealing since it involves multiple catalytic cycles catalyzed by a single metal catalyst PtCl(4). We observed a remarkable enhancement of the rate when reactions were run under microwave-assisted conditions.

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.

Exploiting the higher alkynophilicity of Au-species: development of a highly selective fluorescent probe for gold ions.

A new approach, involving the anchoring-unanchoring of a fluorophore, has been developed for the detection of Au-species. The fluorescent probe was found to be highly selective for sensing gold species in the presence of several other metal ions. A successful application to bioimaging has also been demonstrated with A549 lung cancer cells.