Sharada Duddu

• Associate Professor
• Indian Institute of Technology Hyderabad

A first report on transition-metal-free aluminium chloride mediated isocyanide insertion between two amine nucleophiles have been presented. Also, an unusual C-N bond cleavage allow for the further development of copper mediated ring open-ing cyclization (SROC) strategy for the synthesis of azole fused benzimidazoquinazoline scaffolds. The key feat...

A first report on transition-metal-free aluminium chloride mediated isocyanide insertion between two amine nucleophiles have been presented. Also, an unusual C-N bond cleavage allow for the further development of copper mediated ring open-ing cyclization (SROC) strategy for the synthesis of azole fused benzimidazoquinazoline scaffolds. The key feat...

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(sp3)-H and C(sp2)-H bond functionalization. A sustainable, convenient, metal-free azidation/C-H aminative cyclization approach i...

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 th...

The direct oxidative cleavage of activated alkynes via hydroamination has been described using organic photocatalyst under visible-light irradiation at room temperature. In this reaction, the single electron oxidation of an in situ formed enamine followed by radical coupling with an oxidant finally delivers the oxamate. The key features of this pho...

An efficient, novel and general protocol towards construction of highly functionalized ortho- amido oxobenzoxazine frameworks via ruthenium mediated intermolecular C–H amidation using sulfonyl azides as amination component has been successfully demonstrated for the first time. This protocol is extended to carry out further late-stage functional gr...

An efficient, novel and general protocol towards the synthesis of highly functionalized ortho-amido oxobenzoxazine frameworks via ruthenium catalyzed intermolecular C–H amidation using sulfonyl azides as amidation component has been successfully...

A new one pot assembly of highly functionalized benzo[a]phenazinone fused chromene/bicyclic scaffolds via a domino Knoevenagel intramolecular hetero-Diels-Alder (IMHDA) strategy using a solid state melt reaction (SSMR) of 2-hydroxynaphthalene 1,4-dione, o-phenylenediamine, O-allyl salicylaldehyde/O-vinyl salicylaldehyde derivatives is reported. The...

A novel and convenient protocol for the three component, one‐pot synthesis of multifunctional quinolinopyranpyrazole frameworks via multicomponent reaction is disclosed. This reaction was performed under solvent, catalyst and column chromatography free condition. The reaction is highly diastereoselective and successfully provided the tetracyclic qu...

The trifluoromethylation-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 2H-indazole under metal-free conditions which proceed via a radical mechanism. The combination of photocatalysis and hypervalent iodi...

A concise, one-pot route to Oxazoles and Furocoumarins has been reported. The key step in this transformation involves insitu generation of N-acyliminium ion (NAI) precursor under catalyst and solvent-free conditions, and their further transformations promoted by superacid in the same pot. We have also presented the experimental evidence for the in...

A copper-catalyzed intramolecular α-C–H amination has been developed for the synthesis of quinazolin-4(3H)-one derivatives from commercially available isatoic anhydride and primary and secondary benzylamines via ring-opening cyclization (ROC). This method shows good functional group tolerance and allows access to a range of 2-aryl, 2-alkyl, and spi...

Here we report a visible-light-promoted metal-free regioselective C3-H trifluoromehtylation reaction that proceeds via radical mechanism and which supported by control experiments. The combination of photoredox catalysis and hypervalent iodine reagent provides a practical approach for the present trifluoromethylation reaction and synthesis of a lib...

A stereoselective aminoiodination of activated alkynes with PhI(OAc)2 and amines via multiple‐site functionalization to afford (Z)diethyl 2‐(diphenylamino)‐3‐iodomaleate derivatives with superior yields has been described. The key feature of this reaction is the incorporation of iodide and aryl group concurrently in the same molecule in a stereosel...

A novel and efficient multicomponent quadruple domino reaction (MCQDR) for the assembly of structurally complex molecular architectures via a formation of three rings and three contiguous stereogenic centers has been accomplished with high regio- and diastereoselectivity. Solvent, catalyst and work-up were not required to obtain the target molecule...

p>The direct oxidative cleavage of activated alkynes via hydroamination has been described using organic photocatalyst under visible-light irradiation at room temperature. In this reaction, the single electron oxidation of an insitu formed enamines undergo radical coupling with oxidant which finally delivers the oxamates. The key features of this p...

p>A stereoselective aminoiodination of activated alkynes with PhI(OAc)₂ and amines via multiple-site functionalization to afford ( Z )diethyl 2-(diphenylamino)-3-iodomaleate derivatives with superior yields has been described. The key feature of this reaction is the incorporation of iodide and aryl group concurrently in the same molecule...

Highly functionalized benzazepines have been synthesized by using various substituted Indoles and dialkyl acetylenedicarboxylates under thermal and open air condition. The reaction was carried out in a solvent and catalyst free condition and the products are formed in very good yields. The reaction proceeds in a concerted fashion thus providing pot...

PIDA/TBAB‐promoted complete oxidative geminal diazidofunctionalization of alkynes has been described for the first time. The transformation demonstrates a mechanistically distinctive approach to access geminal diazides, in which TBAB plays a crucial role as brominating agent and in insitu generation of tetrabutylammonium azide. Further, we have dem...

An efficient C3–H functionalization of indazole has been demonstrated. Notably, this method involves chelation-free radical C–H nitration on 2 H -indazole. The radical mechanism was confirmed by control experiments and quantum chemical calculations. The synthetic utility has been proven by the synthesis of bio-relevant benzimidazoindazoles via redu...

We herein report the design and synthesis of three new indole and carbazole based dyes (D1, D2 and D3) with a donor-(π-spacer)-acceptor (D-π-A) configuration with N-methylindole and carbazole as donors, barbituric acid and N-acyloxindole as acceptors/anchoring groups. DFT calculations of three dyes D1, D2 and D3 by using the B3LYP/6-31+G(d) basis s...

Organoiodine(III)-promoted C(sp³)–H azidation was a key step for the cycloaminative process. An unprecedented method for metal-free dehydrogenative N-incorporation into C(sp³)–H and C(sp²)–H bonds for the synthesis of diverse imidazoles has been disclosed. The overall transformation involves the construction of four C–N bonds through hydroamination...

A metal-free regioselective approach to annulated indazoles is presented via dual C−H functionalization of indazole and benzylamine in a cascade fashion. The salient features of the present protocol are regioselective C3-functionalization, one-pot synthesis of annulated scaffolds, metal-free, peroxide-free, operationally simple and wide substrate s...

A facile and convenient approach has been developed for the synthesis of functionalized indazoles via solid state melt reaction using easily accessible starting materials under catalyst-free conditions. This transformation involves electrocyclization via a conjugated nitrene intermediate obtained under thermal conditions. Further anti-tubercular ac...

An efficient protocol for the synthesis of quinazoline derivatives through nickel-catalyzed ligand/base-free oxidative isocyanide insertion under aerobic conditions with intramolecular bis-amine nucleophiles has been developed. A one-pot sequential double annulation cascade (SDAC) strategy involving an opening of isatoic anhydride and annulation to...

A reactive cyclic iminium induced one-pot Groebke-Blackburn-Bienayme (GBB) double annulation cascade (DAC) for the synthesis of skeletally diverse DHIQ salts has been described. The key features of this protocol are transition-metal and solvent-free, mild reaction conditions, robust method, one-step construction of two privileged heterocyclic rings...

A branching double annulation cascade (BDAC) strategy for diverse and complex fused THIQ scaffolds via a highly reactive iminium induced one-pot double cyclization sequence involving Pictect-Spengler type cyclization has been developed for the first time. The salient features of this protocol are direct and rapid access to unprecedented diverse fus...

Bromo-N3-Boc-pyridine-2,3-diamine as well as 2-(N-Boc-aminomethyl)aniline as diamino substrates do not give the desired products.

No abstract is available for this article.

A novel oxidative N-incorporation strategy for synthesis of quinoxaline diesters under metal-free conditions is described for the first time. The mild reaction conditions allow for this transformation via the formation of two C(sp(2))-N bonds utilizing cheaply available NaN3 as the N-atom source. N-Aryl vinylogous carbamates in this study undergo a...

Herein, we have reported an efficient Pd-catalyzed C-H functionalization of 2H-indazole at C3-position via an isocyanide insertion strategy for the synthesis of unprecedented benzoxazinoindazoles, indazoloquinaoxalines and benzoxazinoindazolones for the first time. Our new method provides an operationally simple and versatile route for a selective...

A highly efficient and distinct BF3·OEt2 mediated metal-free SMAC protocol for the synthesis of complex and diverse hybrid molecules viz. indazole fused tetrahydroisoquinolinoquinoxalines, and tetrahydroisoquinolinodiazepine has been developed. The transformation is based on sequential cascade processes involving 2H-indazole formation and deprotect...

We have demonstrated for the first time the use of 2H-indazole as a diene partner in an aza hetero-Diels-Alder reaction leading to highly substituted 4-aminoquinolines via a heterocylic-heterocylic (H-H) strategy and have further developed a tandem one-pot method starting from 2-azidobenzaldehyde by the formation of 2C-N, 1N-N and 1C-C bonds. The k...

An efficient, ligand- and metal-oxidant-free, one-pot, cascade aerobic oxidative, palladium-catalyzed, multicomponent reaction has been developed through isocyanide insertion of less active secondary amide and aromatic amine, which leads to 2-amino-substituted-4(3H)-quinazolinones. This approach proves to be one of the simplest methods for the synt...

Environment-friendly three-component Ugi-type strategy (U-3CR) for the synthesis of a wide variety of α-amino amidines has been developed by using silica gel as promoter, and a novel access to amidino substituted indazoles in a regioselective manner is presented via iron(iii) catalyzed post Ugi cyclization strategy. This method allows an easy const...

A highly efficient and mild protocol for the synthesis of imidazo-fused polyheterocycles via Groebke-Blackburn-Bienayme reaction under the influence of catalytic amount of lanthanum chloride heptahydrate has been described. A wide range of nitrogen-enriched polyheterocycles are synthesized with high yields under neat conditions.

A facile one-pot, four-component domino reaction between 2-(2-bromoethyl)benzaldehyde, isocyanide, amine, and azide for the synthesis of tetrazolyl-tetrahydroisoquinoline derivatives has been developed. The reaction sequence involves intramolecular replacement of halide by iminium nitrogen followed by Ugi-azide reaction. The reaction is catalyst/ad...

A facile and efficient method for the synthesis of α-ketoesters from alcohols and α-carbonyl aldehydes has been developed at room temperature under metal-free conditions for the first time. Various alcohols and α-carbonyl aldehydes could participate in this reaction to afford the desired products in excellent yields.

A one-pot catalyst, solvent, work-up and column free synthesis of 3-aminoimidazo-fused heterocycles by a three-component reaction of a 2-aminoheterocycle, aldehyde, and isocyanide is presented. This efficient and green protocol has the advantages of environmental friendliness, high yields and operational simplicity.

We have described a facile, microwave-assisted, catalyst-free and solvent-free approach to 2H-indazoles and further developed a robust tandem one-pot metal-free strategy for C–C bond formation at the C-3 position of 2H-indazoles leading to a unique class of aza-γ-carboline alkaloid analogues. This straightforward expedient synthesis constitutes an...

Aldehydes of type (I) and (IV), derived from Baylis—Hillman adducts, react with hydroxylamine hydrochlorides to yield nitrones.

Dipyrrins are valuable precursors to dyes [dipyrrinatoboron difluoride, bis(dipyrrinato)-zinc(II) complexes] and serve as ligands in a variety of self-assembled materials. Six new dipyrrin-containing architectures have been synthesized. The architectures include bis(dipyrrinato) complexes containing copper(II) or palladium(II), a dipyrrin bearing a...

A facile method for the simple synthesis of tetracyclic indoloisoxazolidine frameworks from Baylis-Hillman derivatives through formation of nitrones in situ followed by an intramolecular [3+2]-dipolar cycloaddition reaction sequence is described. High regio- and stereoselectivity, excellent yields, together with the creation of two rings and three...

A facile regio- and stereoselective synthesis of functionalized pyrrolidines, spiropyrrolidines, and spiropyrrolizidines using the Baylis-Hillman adducts derived from nitroolefins via intermolecular [3+2]-cycloaddition reaction is reported.

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The organo-base, 1,1,3,3-tetramethylguanidine, mediates the Cannizzaro reaction of reactive aromatic aldehydes in water thus providing the corresponding alcohols and acids. Application of formaldehyde as a sacrificial aldehyde for the cross-Cannizzaro reaction is also presented.

Porphyrins have been shown to be a viable medium for use in molecular-based information storage applications. The success of this application requires the construction of a stack of components ("electroactive surface/tether/charge-storage molecule/linker/electrolyte/top contact") that can withstand high-temperature conditions during fabrication (up...

Dipyrrins are valuable precursors to dyes [dipyrrinatoboron difluoride, bis(dipyrrinato)-zinc(II) complexes] and serve as ligands in a variety of self-assembled materials. Six new dipyrrin-containing architectures have been synthesized. The architectures include bis(dipyrrinato) complexes containing copper(II) or palladium(II), a dipyrrin bearing a...

[reaction: see text] Palladium porphyrins are valuable photosensitizers and luminescent agents in biology and materials chemistry. New methodology is described wherein a 1-acyldipyrromethane is converted into the palladium chelate of a trans-A(2)B(2) porphyrin via a one-flask reaction. The reaction entails self-condensation of the 1-acyldipyrrometh...

A facile and one-pot synthesis of 2-benzoxepines, from Baylis–Hillman adducts that is, alkyl 3-aryl-3-hydroxy-2-methylenepropanoates, via treatment with HCHO in the presence of concd H2SO4, involving tandem construction of C–O and C–C bonds via Prins-type and Friedel–Crafts reactions, is described.

The Baylis-Hillman coupling between activated alkenes and alkyl 2-(bromomethyl)prop-2-enoates in the presence of DABCO (or DBU) leading to the formation of 2,4-functionalized 1,4-pentadienes, has been described.

The Baylis-Hillman coupling between activated alkenes and alkyl 2-(bromomethyl)prop-2-enoates in the presence of DABCO (or DBU) leading to the formation of 2,4-functionalized 1,4-pentadienes, has been described.

A simple synthesis of functionalized (1H)-quinol-2-ones and quinolines from the Baylis–Hillman adducts, i.e. alkyl 3-hydroxy-2-methylene-3-arylpropanoates and β-hydroxy-α-methylene-β-arylalkanones, respectively, has been described.

Asymmetric synthesis of (−)-methyl 3-aryl-2-methylene-3-(prop-2-yn-1-yloxy)propanoates in 25–40% enantiomeric purities via the reaction of methyl (2Z)-3-aryl-2-(bromomethyl)prop-2-enoates with prop-2-yn-1-ol in the presence of quinidine is described.

A novel synthesis of functionalized 1,4-pentadienes via the reaction of acrylonitrile with allyl halides, derived from Baylis–Hillman adducts, in the presence of DABCO has been described, demonstrating for the first time the application of allyl halides as electrophiles in the Baylis–Hillman reaction.