Mono and di -C-H acetoxylation of 2-aryloxyquinoline-3-carbaldehydes.

2-Aryloxyquinolines are well known for various biological activities. In this report, we have developed a novel protocol for introducing an acetoxy functional group on the aryl sp carbon of 2-aryloxyquinoline-3-carbaldehyde using a palladium catalyst for the first time. Interestingly, this C-H acetoxylation reaction is highly chemo- and site-selective.

Distal -C-H functionalization of α-substituted cinnamates.

Development of a novel strategy for the palladium-catalyzed selective -C-H activation of α-substituted cinnamates and their heterocyclic analogues with various alkenes using nitrile as a directing group (DG) has been described. Importantly, we introduced naphthoquinone, benzoquinones, maleimides and sulfolene as coupling partners in the -C-H activation reaction for the first time. Notably, allylation, acetoxylation and cyanation were also achieved through distal -C-H functionalization.

Palladium-catalyzed remote -C-H olefination of cinnamates.

The palladium-catalyzed remote -C-H olefination of geometrically challenging substituted cinnamates using a nitrile directing group derived from 2-cyanobenzoic acid has been described. This new protocol is applicable to various olefin coupling partners and provides the corresponding -olefinated products in very good yields and with high selectivity. In addition, using this methodology, a variety of acrylates with tethered bioactive molecules, such as naphthoquinone, methyl salicylate, paracetamol, thymol, sesamol, chalcone, naproxen, cholesterol and estrone, have been coupled to produce the desired -olefinated products.

Azomethine ylide cycloaddition of 1,3-dienyl esters: highly regio- and diastereoselective synthesis of functionalized pyrrolidinochromenes.

An efficient protocol for the synthesis of tricyclic pyrrolidinochromenes has been developed an intramolecular 1,3-dipolar cycloaddition of azomethine ylides generated from 1,3-dienyl ester tethered -hydroxyarylaldehyde and glycine esters. The reaction is highly regio- and diastereoselective in nature and provided the potentially bioactive pyrrolidine fused tricyclic cycloadducts in excellent yields with wide substrate scope. Interestingly this reaction constructs two rings and four contiguous stereogenic centers in which one of them is an all carbon quaternary center in a unique fashion.

Ester-directed orthogonal dual C-H activation and aryl C-H alkenylation distal weak coordination.

An unprecedented orthogonal cross-coupling between aromatic C(sp) and aliphatic olefinic C(sp) carbons of two same molecules dual C-H bond activation in an intermolecular fashion has been developed using a distal ester-directing group. This new coupling reaction led to the synthesis of the highly functionalized 1,3-diaryl molecular architecture in very good yields and with high chemo- and regioselectivities. In addition, using ester as the distal directing group, C-H olefination of α-methyl aryl acrylates and cinnamic esters with various alkenes has been achieved in very good yields and with a wide range of substrate scope.

Photocatalytic Visible-Light-Induced Nitrogen Insertion via Dual C(sp)-H and C(sp)-H Bond Functionalization: Access to Privileged Imidazole-based Scaffolds.

Here we have demonstrated a visible-light-mediated metal-free organic-dye-catalyzed dehydrogenative N-insertion leading to highly substituted imidazoles and privileged dihydroisoquinoline-based imidazole derivatives via C(sp)-H and C(sp)-H bond functionalization. A sustainable, convenient, metal-free azidation/C-H aminative cyclization approach in the absence of stoichiometric oxidants is presented. This protocol involves a rare photoinduced iminyl radical as a key intermediate for the "N" insertion.

Intramolecular [3 + 2] nitrone cycloaddition reaction: highly regio and diastereoselective synthesis of bicyclo[3.2.1]octane scaffolds.

A regio and diastereoselective strategy has been developed for the synthesis of complex bicyclo[3.2.1]octane scaffolds from the reaction of readily accessible vinylogous carbonates with N-substituted hydroxylamine hydrochlorides via intramolecular 1,3-dipolar nitrone cycloaddition reaction.

Rhodium-Catalyzed Diastereoselective [3 + 2] Cycloaddition of Carbonyl Ylide: An Access to the Core Ring System of Cordigol and Lophirone H.

This paper describes a new synthetic strategy for the construction of tricyclic chromeno/quinolino furan frameworks via creation of two new rings and three contiguous stereogenic centers with high diastereoselectivity through a rhodium-catalyzed intramolecular carbonyl ylide cycloaddition reaction for the first time. This protocol allows the synthesis of the core ring system of natural products such as cordigol and lophirone H.

Ruthenium-catalyzed, site-selective C-H activation: access to C5-substituted azaflavanone.

A site-selective ruthenium-catalyzed keto group assisted C-H bond activation of 2-aryl tetrahydroquinoline (azaflavanone) derivatives has been achieved with a variety of alkenes for the first time. A wide range of substrates was utilized for the synthesis of a wide variety of alkenylated azaflavanones. This simple and efficient protocol provides the C5-substituted azaflavanone derivatives in high yields with a broad range of functional group tolerance.

Domino ring opening and selective O/S-alkylation of cyclic ethers and thioethers.

Chemoselective domino ring opening and selective O/S-alkylation of ethers/thioethers over enol C/O alkylation has been observed. Various 2-aryl chromanones/thiochromanones with alkyl/allyl bromides were smoothly converted into the corresponding highly functionalized ethers and thioethers in excellent yields with high selectivity. An unusual, chemoselective domino ring opening and selective ether/thioether O/S-alkylation over.

Cascade annulation reaction (CAR): highly diastereoselective synthesis of pyranopyrazole scaffolds.

An unprecedented domino protocol for the novel synthesis of highly diverse and functionalized tetrahydro pyranopyrazole scaffolds using chalcone epoxide has been reported for the first time. This synthetic protocol generates three consecutive stereogenic centres in a highly diastereoselective manner with the formation of vicinal diol and a quaternary carbon centre. A wide range of substrates were utilized for the scope of this methodology and provided very good yields of pyranopyrazoles.

Construction of hybrid polycyclic quinolinobenzo[a]phenazinone architectures using solid-state melt reaction (SSMR).

An efficient and versatile protocol for the synthesis of hybrid polycyclic quinolinobenzo[a]phenazinones has been developed under SSMR condition via intramolecular domino Knoevenagel-hetero-Diels-Alder reaction involving the generation of two new six membered fused rings and three contiguous stereogenic centers.

Two step, one-pot sequential synthesis of functionalized hybrid polyheterocyclic scaffolds a solid state melt reaction (SSMR).

A new one pot assembly of highly functionalized benzo[]phenazinone fused chromene/bicyclic scaffolds a domino Knoevenagel intramolecular hetero-Diels-Alder (IMHDA) strategy using a solid state melt reaction (SSMR) of 2-hydroxynaphthalene 1,4-dione, -phenylenediamine, -allyl salicylaldehyde/-vinyl salicylaldehyde derivatives is reported. The formation of five new bonds (two C-C bonds and three C-O bonds), three six-membered rings, and three stereogenic centers in a one-pot manner is very attractive. Ease of reaction with short time, good yields with water as the only byproduct and work up free procedure are some of the excellent features of the present protocol.

Regioselective C3-H Trifluoromethylation of 2 H-Indazole under Transition-Metal-Free Photoredox Catalysis.

Trifluoromethyl-substituted heteroarenes are biologically active compounds and useful building blocks. In this sequence, we have developed a visible-light-promoted regioselective C3-H trifluoromethylation of 2 H-indazole under metal-free conditions, which proceeds via a radical mechanism. The combination of photocatalysis and hypervalent iodine reagent provides a practical approach to a library of trifluoromethylated indazoles in 35-83% yields.

A rearrangement involving a solid-state melt reaction for the synthesis of multifunctional tetrasubstituted olefins.

A catalyst- and solvent-free intramolecular rearrangement sequence leading towards benzimidazole-tethered tetrasubstituted olefins through a solid-state melt reaction (SSMR) involving imine formation, cyclization, N-allylation and isomerization has been realized for the first time. Interestingly, only water is the byproduct in this novel quadruple domino reaction. Furthermore, the reaction is highly stereoselective, atom economical and environmentally benign in nature.

Palladium catalyzed chemo- and site-selective C-H acetoxylation and hydroxylation of oxobenzoxazine derivatives.

An efficient protocol for the introduction of acetoxy and hydroxy functionalities on unactivated aryl sp2 carbons of oxobenzoxazine derivatives via an ortho-C-H activation reaction using a palladium catalyst has been developed for the first time. Interestingly, this intermolecular C-H functionalization reaction takes place in a facile and simple manner with high chemo- and site selectivity.

A novel multicomponent quadruple/double quadruple domino reaction: highly efficient synthesis of polyheterocyclic architectures.

A novel multicomponent quadruple domino reaction (MCQDR) for the assembly of structurally complex molecular architectures via the formation of three rings and three contiguous stereogenic centers has been accomplished with high regio- and diastereoselectivity. Solvents, catalysts and work-up were not required to obtain the target molecules. In addition, this new protocol is also extended for the multicomponent double quadruple domino reaction (MCDQDR) to create novel polyheterocyclic architectures in an orthogonal manner.

Solvent and catalyst free ring expansion of indoles: a simple synthesis of highly functionalized benzazepines.

Highly functionalized benzazepines have been synthesized by using various substituted indoles and dialkylacetylene dicarboxylates under thermal and open air conditions. The reaction was carried out in a solvent and under catalyst free conditions and the products are formed in very good yields. The reaction proceeds in a concerted fashion thus providing potentially bioactive benzazepines by ring expansion of a five-membered indole ring.

A distal vinyl shift (DVS) through quadruple domino reaction: synthesis of -vinyl benzoheterocyclic scaffolds.

A conceptually novel Distal Vinyl Shift (DVS) through quadruple domino reaction involving imine formation, oxazole/thiazole/oxazine formation, aza-Michael addition and selective retro oxa/aza-Michael addition leading towards -vinyl benzoxazoles/benzothiazoles/-vinyl 1,3-benzoxazines has been developed for the first time. This reaction is highly stereoselective and was carried out efficiently without using any catalyst as well as column chromatography purification with wide substrate scope in very good to excellent yields.

A Direct Cycloaminative Approach to Imidazole Derivatives via Dual C-H Functionalization.

Organoiodine(III)-promoted C(sp)-H azidation was a key step for the cycloaminative process. An unprecedented method for metal-free dehydrogenative N-incorporation into C(sp)-H and C(sp)-H bonds for the synthesis of diverse imidazoles has been disclosed. The overall transformation involves the construction of four C-N bonds through hydroamination-azidation-cyclization sequence.

One-Pot Synthesis of Benzothiazole-Tethered Chromanones/Coumarins via Claisen Rearrangement Using the Solid State Melt Reaction.

A novel protocol has been successfully established for the efficient synthesis of benzothiazole-tethered chromanone/coumarin scaffolds via Claisen rearrangement using a solid state melt reaction in a one-pot manner. Benzothiazole formation and Claisen rearrangement involve the cleavage of S-S and C-O bonds and formation of C-S, C═N, and C-C bonds in a single operation without using a catalyst or solvent.

Crystal structure of methyl (2Z)-2-{[N-(2-formyl-phen-yl)-4-methyl-benzene-sulfonamido]-meth-yl}-3-(4-meth-oxy-phen-yl)prop-2-enoate.

In the title compound, C26H25NO6S, the S atom shows a distorted tetra-hedral geometry, with O-S-O [119.46 (9)°] and N-S-C [107.16 (7)°] angles deviating from ideal tetra-hedral values, a fact attributed to the Thorpe-Ingold effect.

A novel protocol for the facile construction of tetrahydroquinoline fused tricyclic frameworks via an intramolecular 1,3-dipolar nitrile oxide cycloaddition reaction.

An efficient method towards the synthesis of quinoline fused tricyclic compounds involving an intramolecular 1,3-dipolar nitrile oxide cycloaddition reaction utilizing Baylis-Hillman derivatives in good yields has been described for the first time. A highly functionalized tricyclic framework was created by forming two rings and two adjacent stereocentres through the formation of two N-C bonds, one C-C bond and one O-C bond in a highly regio and diastereoselective manner.

Stereoselective construction of functionalized tetracyclic and pentacyclic coumarinopyranpyrazole/pyrimidinedione/coumarin scaffolds using a solid-state melt reaction.

An assembly of tetra / pentacyclic hybrid scaffolds have been synthesized for the first time using a solid-state melt reaction in a stereoselective fashion with excellent yields.

Methyl 3'-(2,5-di-methyl-benz-yl)-1'-methyl-2-oxo-4'-phenyl-spiro-[indoline-3,2'-pyrrolidine]-3'-carboxyl-ate chloro-form monosolvate.

In the title solvate, C29H30N2O3·CHCl3, the dihedral angle between the indole ring system (r.m.s.