Siddharth Sharma

• PhD
• Assistant Professor at Mohanlal Sukhadia University

A grinding-induced catalyst- and solvent-free domino multicomponent reaction for the synthesis of 1,4-dihydropyridines has been developed using aldehydes, amines, DEAD (diethyl acetylenedicarboxylate), and malononitrile/ethyl cyanoacetate. The synthesized 1,4-dihydropyridines were efficiently converted into novel tacrine analogs 7a–7e using micelle...

Can't smell this: An integrated continuous-flow microfluidic setup enables in situ generation, extraction, separation, and reaction of foul-smelling isocyanides with little exposure to the surroundings. Isocyanides were generated by dehydration of the corresponding N-substituted formamides, and several representative isocyanide-based organic reacti...

Putting osmium in its place: The immobilization of hazardous OsO4 on polymer nanobrushes in a microreactor is a safe, effective, and green concept. The method allows reactions to be performed in a time- and chemical-saving manner, with little environmental impact, as compared to spill-over bulk processes.

We have successfully developed a single nucleotide (adenosine 5′-diphosphate)-catalyzed enantioselective direct reductive amination of aldehydes and ketones using a Hantzsch ester as reducing agent. The process is a simple, efficient and a real mimic of the NADH reduction approach for the synthesis of structurally diverse amines. This reaction is t...

We describe the novel electrochemical multicomponent reaction (e-MCR) of readily available isocyanides, thiols and carboxylic acids to form N-substituted S-thiocarbamate derivatives that are found in several biologically active compounds. The...

The combination of the Ugi reaction and electro-organic synthesis can aid in the creation of novel heterocycles that have not been previously explored. In this study, a new strategy utilizing bis-amides from the Ugi reaction has been developed, which can produce C-S, C-Se, and C-C═O functionalized five-membered spirolactams mediated by electricity...

A simple and efficient electrochemical method that utilizes modulation of the cell voltage to cause structural alterations in 2H-indazole is introduced. This method enables the C-3 acyloxylation of 2H-indazole and promotes the transfer of the acyl group from C-3 to N-1, allowing the N-acylation of 2H-indazoles. Additionally, the application of the...

Despite the appreciation for electro-organic synthesis, postmulticomponent reaction transformation chemistry rarely exploits this powerful technology. Herein, we explore post-Ugi cyclization reactions using N-centered radical-mediated intramolecular ipso cyclization to synthesize diverse spirocyclic variants of 4-imidazolidinones through the use of...

A novel electrochemical cross-dehydrogenative C-S bond coupling of aryl thiols with 2H-indazole is reported. Thiol-functionalized 2H-indazoles were synthesized under catalyst-, oxidant-, and metal-free conditions with innocuous hydrogen as the sole byproduct at ambient temperature. Furthermore, continuous electrochemical flow conditions using a gra...

The indolizines nucleus is an important element of many synthetic molecules with significant biological activity. An efficient methodology for the synthesis of a variety of indolizines from quinazolinone, pyridine, and chalcone via I2/FeCl3 has been described. The reaction was promoted through Zwitterion formation/cyclization/aromatization sequence...

An expeditious synthetic strategy to access functionalized S-thiocarbamates was developed in good to excellent yields and with high current efficiencies. Readily available isocyanides and thiols were used as the starting materials under simple metal- and oxidant-free reaction conditions avoiding an inert atmosphere. The practical application of the...

A new series of 1,2,4-trioxanes 9a1-a4, 9b1-b4, 10–13 and 9c1-c4 were synthesized and evaluated against multidrug-resistant Plasmodium yoelii nigeriensis in Swiss mice via oral and intramuscular (i.m.) routes. Adamantane-based trioxane 9b4, the most active compound of the series, provided 100% protection to the infected mice at the dose 48 mg/kg ×...

Malaria epidemics represent one of the life-threatening diseases to low-income lying countries which subsequently affect the economic and social condition of mankind. In continuation in the development of a novel series of 1,2,4-trioxanes 13a1-c1, 13a2-c2, and 13a3-c3 have been prepared and further converted into their hemisuccinate derivatives 14a...

An efficient and highly diastereoselective synthesis of schizocommunin analogues has been achieved through an iron-catalyzed C(sp³)-H/C(sp³)-H cross-dehydrogenative coupling reaction between 2-methyl quinazolinones and indolin-2-ones. This method requires air (molecular oxygen) as an oxidant instead of chemical equivalent oxidising agents and prefu...

Catalyst- and oxidant-free synthesis of 6-aryl phenanthridines and amides through electrochemical reaction is reported in this study. The coupling reaction proceeds by the cathodic reduction of in situ formed diazonium...

This work discloses an electrochemical oxidative cross-coupling of amines with aryl and aliphatic isocyanides. In an undivided cell, the reaction proceeds without involving any transition-metal catalyst, oxidant, or toxic reagents providing carbodiimides in good yields, thereby circumventing stoichiometric chemical oxidants, with H2 as the only byp...

A metal-free diastereo-/regioselective modular synthetic approach for the synthesis of highly constrained tetrahydroquinoline-fused tetracyclic heterocycles from easily available substrates has been developed. This two-step strategy utilizes an Ugi four-component reaction, followed by the intramolecular spirocarbocyclization and iodination reaction...

An environmentally benign highly atom-economic protocol for the construction of the C–C bond has been developed under catalyst- and solvent-free conditions. This protocol involves the efficient coupling of 2-methyl quinazolinones with isatin for the highly diastereoselective access of schizocommunin derivatives in excellent yields (up to 97%). Furt...

A divergent regioselective palladium (II) catalyzed approach through post Ugi cyclization is described. The Ugi adduct underwent intramolecular ortho-hydroarylation via 6-endo-dig cyclization for the direct access to 4-aryl-2-quinolones. Incorporation of iodine at the C-3 position of 2-quinolone followed by Suzuki-Miyaura coupling results into the...

Metal catalyzed post-Ugi cyclization of bis-amides is reported in this study. Exposure of bis-amides to Pd(II) catalyst triggered the formation of seven-membered benzoxazepinones. This investigation established that changing the catalyst to a Echavarren’s gold(I) turned off cyclization to seven member ring and turned on 6-exo-dig annulations to aff...

We report here a novel IBX promoted oxidative coupling of primary amines and its utilization to Ugi reaction. Advantageously, the reaction could be carried out in choline chloride-urea as a natural deep eutectic solvent. A range of imines and bis-amides from pseudo-four component oxidative Ugi reaction could be synthesized under mild and metal-free...

A new and efficient method for the synthesis of thiourea derivatives by a sequential one-pot, three-component reaction between aromatic isocyanides, amines, and 1,2-di-tert-butyldisulfane (DTBS) was developed and 27 different examples were synthesized in good to excellent yields. DTBS was identified as an effective sulfur surrogate without the use...

A versatile Pd/Fe3O4 supported on N-doped reduced graphene oxide (N-rGO) catalyst was developed to carry out the synthesis of quinazolinones and phenanthridines under extremely mild conditions through isocyanide insertion cascades. The supported Pd/Fe3O4 nanoparticles could be easily recovered from the reaction mixture and reused several times with...

Gas and liquid streams are invariably separated either by a solid wall or by a membrane for heat or mass transfer between the gas and liquid streams. Without the separating wall, the gas phase is present as bubbles in liquid or, in a microsystem, as gas plugs between slugs of liquid. A continuous and direct contact between the two moving streams of...

Generation of hydrogen from renewable sources and its safe utilization for efficient one-pot upgrading of renewable biofuels are a challenge. Bimetallic PdAg catalyst supported on Fe3O4/nitrogen-doped reduced graphene oxide (N-rGO) were synthesized for hydrogen generation from formic acid with high TOF (497 h-1 at 50 °C), and the hydrogen was subse...

The sustainable green chemistry associated with lignocellulosic biomass is of current interest for producing various chemical feedstocks via multi-step transformation processes. Here we introduce a chemical platform system for the multicomponent cascade transformation of natural lignocellulosic biomass resources. We demonstrate the concept by devel...

The quest to reduce greenhouse gases has triggered the development of new chemical fixation of carbon dioxide. Given the importance of CO2 based transformation chemistry, we demonstrate fixation of CO2 for oxazolidinedione synthesis via a novel multicomponent synthesis. In the presence of a catalytic amount of Cu2O, various 2-bromo-3-phenylacrylic...

Palladium catalyzed cascade coupling of substituted urea derivatives and tert-butyl isocyanide for the efficient synthesis of phenylamino-substituted quinazolinones has been developed in moderate to good yields. This method provides a short and alternative approach for the synthesis of quinazolinones derivatives which are valuable compounds with bi...

Given the importance of homogeneous catalysts recycling in organic chemistry, we have developed a unique microfluidic loop system for automated continuous recirculation of a soluble polymer supported metal catalyst for novel isocyanide cross-coupling reactions under thermomorphic multicomponent solvent (TMS) conditions. Our system provides an innov...

Microreactors have been proven to be efficient tools for a variety of homogeneous organic transformations due to their mixing efficiency, which results in very fast reactions, better heat and mass transfer, and simple scale-up. However, in heterogeneous catalytic reactions each catalyst needs an individual substrate as support. Herein, a versatile...

Here, we demonstrate that graphene oxide (GO) can be converted to N-doped reduced GO (rGO) that could become a substitute for N-doped graphene. Simultaneous doping and reduction can be accomplished for the purpose by simply mixing GO with hydrazine and then continuously sonicating the solution at 65 oC. A high level of reduction is realized as evid...

Two types of whole ceramic-like microreactors were fabricated from inorganic polymers, polysilsesquioxane (POSS) and polyvinylsilazane (PVSZ), that were embedded with either perfluoroalkoxy (PFA) tube or polystyrene (PS) film templates, and subsequently the templates were removed by physical removal (PFA tube) or thermal decomposition (PS). A POSS...

Despite the long history of isocyanide chemistry, the full utilization of these compounds has been hindered by their distressing odor. In their Communication on page 7564 ff., D.‐P. Kim et al. report the development of an automated continuous microfluidic system that produces products through the serial synthesis, purification, and in situ consumpt...

So kommt Osmium an seinen Platz: Die Immobilisierung von gefährlichem OsO4 an Polymernanobürsten in einem Mikroreaktor ist ein sicheres, effektives und ,,grünes“ Konzept. Auf diese Art lassen sich Reaktionen gegenüber großvolumigen Ansätzen zeit‐ und chemikaliensparend und mit wenig Einfluss auf die Umwelt durchführen.

Osmiumtetroxid eignet sich hervorragend für die katalytische Dihydroxylierung und oxidative Spaltung von Olefinen, ist aber hochtoxisch, gefährlich, teuer und flüchtig. In der Zuschrift auf S. 6867 ff. stellen D.‐P. Kim et al. einen sicheren und effizienten Nanobürsten‐Mikroreaktor vor, der die vollständige Verwendung von OsO4 ermöglicht und zudem...

Arylethanones of type (I) and (IV) are applied as Julia coupling partners for the reaction with aromatic aldehydes to give chalcones and flavanones, correspondingly.

The simple and efficient method using a Hantzsch ester as reducing agent and ADP as catalyst represents a real mimic of the NADH reduction approach.

A series of 2-arylbenzothiazoles and 2-arylbenzoxazoles were synthesized by the reactions of aldehydes and 2-aminothiophenol and 2-hydroxythiophenol, respectively, using glucose oxidase (GOX)–chloroperoxidase (CPO) catalytic system under oxygen atmosphere.

A new application of Julia–Kocienski olefination for the synthesis of chalcones and flavanones has been described. 2-(Benzo[d]thiazol-2-ylsulfonyl)-1-phenylethanones have been developed as new reagents for direct Julia–Kocienski olefination with aldehydes in the presence of a base, afforded chalcones in good to excellent yields. Whereas, 2-(benzo[d...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Libraries of benzoxanthenes, as well as of benzochromenes, were efficiently synthesized via one-pot, three-component reactions of 2-naphthol, aldehydes, and cyclic 1,3-diketones/malononitrile/ethyl cyanoacetate in the presence of catalytic amount of ceric ammonium nitrate (CAN) under solvent free conditions. The protocol offers rapid synthesis of s...

A series of pyranocoumarin derivatives were synthesized and evaluated in vivo for their anti-hypergly-cemic as well as anti-dyslipidemic activities. Compounds 7a, 7c, 8a, 8b, 8c, 8e and 8f have shown prom-ising anti-hyperglycemic activities in sucrose loaded model (SLM) as well as sucrose challenged streptozotocin induced diabetic rat model (STZ)....

A novel multi-component reaction of indoles, formaldehydes, and tertiary aromatic amines is described for the synthesis of dialkylaminoarylated indoles using silica-supported perchloric acid (HClO4–SiO2) as an inexpensive and highly efficient catalyst. The key features of this multi-component reactions are operational simplicity, mild reaction cond...

N-aryl-1,4-dihydropyridines 2a-n were synthesized via iodine catalyzed three-component reaction of cinnamaldehydes, anilines and 2-keto esters in methanol. The synthesized compounds were screened for their antidyslipidemic and antioxidant activity in vivo and in vitro. Compounds 2a, 2g, and 2l have exhibited promising lipid and TG lowering activity...

A series of pyranocoumarin derivatives were synthesized and evaluated in vivo for their anti-hyperglycemic as well as anti-dyslipidemic activities. Compounds 7a, 7c, 8a, 8b, 8c, 8e and 8f have shown promising anti-hyperglycemic activities in sucrose loaded model (SLM) as well as sucrose challenged streptozotocin induced diabetic rat model (STZ). Co...

Human hemoglobin (HbA) efficiently catalyses the oxidative aromatization of 1,4-dihydropyridines (1,4-DHPs) and pyrazolines with hydrogen peroxide in phosphate buffer. The results of the study reveal that the rates of oxidative aromatization of 1,4-DHPs are substituent dependent. Thus, the present study is very useful in understanding the metabolis...

We have designed 1,3-disubstituted-5-membered heteroaromatic ring system as a common core motif from known anti-hyperglycemic agents. Designed compounds were synthesized and screened for in vivo anti-hyperglycemic activity in sucrose loaded model (SLM), sucrose-challenged streptozotocin-induced diabetic rat model (STZ-S) as well as db/db mice model...