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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 that it allows direct and rapid access to unprecedented diverse fused THIQ skeletons, is metal/catalyst free, has a cleaner reaction profile, provides good to excellent yields, and is a convenient approach. This catalyst-free domino process facilitates the double annulation with a variety of scaffold building agents via two C–N and one C–X (X = C, N, O) bond formation in a single step under uniform reaction conditions. Furthermore, we reveal an unusual dual BDAC sequence leading to N–N-linked isoquinoline dimer.

An efficient 1,6-conjugate addition of 3-substituted indoles to para-quinone methides (p-QMs) using catalytic amount of Bi(OTf)3 is described. This mild and atom-economical protocol allowed us to access unsymmetrical diaryl(2-indolyl)methanes in moderate to excellent yields under solvent-free grinding conditions.

The first example of hydrogenation of amides homogeneously catalyzed by an earth-abundant metal complex is reported. The reaction is catalyzed by iron PNP pincer complexes. A wide range of secondary and tertiary N-substituted 2,2,2-trifluoroacetamides were hydrogenated to form amines and trifluoroethanol.

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(sp2)–N bonds utilizing cheaply available NaN3 as the N-atom source. N-Aryl vinylogous carbamates in this study undergo azidation at enamino C(sp2)–H selectively. The robustness of this strategy is further demonstrated by the synthesis of a valuable 1,4,5,8-tetraazaphenanthrene derivative using a mild and convenient approach.

Polysaccharides are ideal candidates for drug delivery and biomedical applications as they are easily obtained from natural sources. Furthermore, they can be subjected to a wide range of chemical and enzymatic reactions, they have biocompatible and biodegradable properties and have inherently low immunogenicity. Polysaccharides are potentially the materials of choice for the development of "smart" delivery systems, which are capable of releasing, at the appropriate time and site of action, an encapsulated drug. This Review examines various aspects of the crosslinking of polysaccharides, either for a single polysaccharide or mixtures, and also natural-synthetic hybrids. The Review focuses on the strategies for using these biodegradable polymers for controlled drug delivery, and examines in particular polysaccharide-drug conjugates, the encapsulation of drugs in hydrogels and aerogels, and the self-assembly of polysaccharide drug-loaded nanoparticles.

A one-pot three component reaction has been developed for the synthesis of substituted cyclopropanes employing 4-bromomethyl-2H-chromen-2-one/quinolin-2(1H)-ones, aromatic aldehydes and activated nitriles. The room temperature reaction in aqueous medium has been found to be diastereoselective and high yielding.

The mild, metal-free [3 + 2] dipolar cycloaddition reaction of allenoates with ylides deriving from pyridine, quinoline or isoquinoline derivatives provides a diverse range of the title products in high yields.

A covalently anchored phosphine free Pd(II) based 2,2′-dihydroxybenzophenone (DHBP) complex over organofunctionalized SBA-15 is synthesized by the reaction of aminofunctionalized SBA-15 (NH2SBA-15) and a DHBP ligand, and further complexation with PdCl2 to get Pd(II)—DHBP@SBA-15.

Ethyl bromofluoroacetate has been developed as a precursor for the convenient synthesis of unsymmetrical α,α-diarylacetates featuring indoles, anilines, and other electron-rich aromatics. In conjunction with a mild Lewis acid catalyzed C-N → C-C exchange, intermediate arylglycines can be synthesized and transformed into α,α-diarylacetates in a one-pot protocol, resulting in a net diarylation reaction exhibiting a wide scope. In the context of diarylacetates, the synthetic equivalence of the fluorinated reagent with α-nitro-α-diazo carbonyls was established.

A phenyliodine(III) diacetate (PIDA)-mediated, highly efficient and tandem approach for the synthesis of aryldiazenylisoxazolo(isothiazolo)arenes from simple 2-amino-N′-arylbenzohydrazides has been developed. The reaction proceeds via formation of (E)-(2-aminoaryl)(aryldiazenyl)methanone as the key intermediate, followed by intramolecular oxidative O–N/S–N bond formation in one pot at room temperature. The quiet different reactivity of the substrate is due to the formation of a diazo intermediate which encounters a nucleophilic attack by carbonyl oxygen on the electrophilic amine to produce isoxazole products, as compared to the previous reportsa,b,4 in which an N-acylnitrenium ion intermediate is intramolecularly trapped by an amine group.

The tetracyclic indoloindol-3-one core has been forged from easily accessible 2,2′-bis-bromochalcones employing a reaction cascade comprising Cu-catalyzed SNAr with azide; nitrene C–H insertion and intramolecular Ullmann reaction with all three C–N bond formations in one-go.

Various multisubstituted benzothiophenes are obtained by an one-pot, two-step method involving the palladium-catalyzed intramolecular C—H functionalization-arylthiolation of in situ generated enethiolate salts.

The activation of title compound (II) employing a visible light mediated photoredox transformation is reported.

A transition metal-free, vinylic bromide displacement reaction of bromoallyl sulfones (II) with phenolate nucleophiles is reported.

A bis(amino)cyclopropenylidene-catalyzed direct method for the synthesis of α,α′-diarylated ketones from aromatic as well as heteroaromatic aldehydes has been developed. This unprecedented organocatalytic protocol offers access to a wide range of α,α′-diarylated ketones in moderate to excellent yields under mild conditions through umpolung of aldehydes followed by 1,6-conjugate addition with para-quinone methides.

A palladium-catalyzed domino process to access unsymmetrical diarylindolylmethanes has been developed through the annulation of o-alkynylanilines followed by 1,6-conjugate addition with p-quinone methides (p-QMs) under relatively mild conditions. The broad substrate scope of this methodology was demonstrated through the use of a wide range of substituted o-alkynylanilines and p-quinone methides, and in most cases, the unsymmetrical diarylindolylmethanes could be prepared in moderate to excellent yields. Notably, this method does not require any amino group protection. Moreover, 100% atom economy makes this transformation attractive from a green chemistry perspective.

An environmentally benign protocol for the synthesis of N-(pyridine-2-yl)amides from aldehydes and 2-aminopyridines has been developed under mild reaction conditions. This approach requires Cu(OTf)2 as a catalyst, and inexpensive molecular iodine as an oxidant under anionic micellar catalysis in aqueous medium at room temperature.

A series of 2-((arylamino)methyl)-5-(3-methoxyphenyl)-1-phenyl-1H-1,2,4-triazole-3-thione derivatives have been synthesized and characterized by FT-IR, NMR, mass spectral and elemental analysis. Compounds (MM4a-m) have been evaluated for their in vitro antibacterial activity against selected gram-positive and gram-negative bacteria and in vitro antifungal activity against fungal pathogens by using broth dilution method. The compounds have been screened for antitubercular activity against Mycobacterium tuberculosis H37Rv strain by using L J Slope method. Of all the compounds, MM4d, MM4e, MM4j and MM4k show good antibacterial activity and MM4a, MM4d, MM4e and MM4j compounds have been found to possess good antitubercular activity.

3-Hydroxyindanones, prepared through aldolization of ortho-diacylbenzenes (I) and (III), undergo SOCl2 mediated dehydroxylation to afford indenone derivatives.

A new and operationally and user-simple domino protocol for the efficient synthesis of 2-alkylidene-1,3-dithiolanes has been developed via molecular iodine mediated iodocyclization of S-allylated α-enolic dithioesters at room temperature. The attractive features of this strategy include mild reaction conditions, short reaction time (5 min), high atom economy, high selectivity, easy purification, excellent yields, and wide substrate scope. Notably, many examples gave the exocyclic double bond of the 1,3-dithiolane with Z-configuration, while others gave E/Z mixtures; interconversion of the E- and Z-isomers was observed under acidic and thermal conditions.

The use of non-toxic and inexpensive Fe(III) nitrate as an oxidant allows the rapid conversion of 1,2-diols of various steric and electronic nature.

Reaction of benzylidenedihydroacridinones (I) with malononitrile using montmorillonite KSF as catalyst leads to the regiospecific formation of expected phenanthroline-3-carbonitriles (V) whilst the use of NaH as base results in the regiospecific formation of unexpected Michael addition products (IV).

A variety of target compounds can be successfully prepared and besides the thioester reactants, phenyl isothiocyanate (XII) is also efficient.

First organocatalytic intramolecular aldolization of ortho -diacylbenzenes to construct highly functionalized 3-hydroxyindanones is described. In this transformation a high trans -selectivity is achieved by the use of metal salt of amino acid. This method allows an easy access to the strained spirocyclic 3-hydroxyindanones related to a number of natural product frameworks. Synthesis of a new class of indole skeleton substituted by 3-hydroxyindanones added an extra essence to this new protocol.

α-Aminophosphonates are prepared by Kabachnik—Fields reaction of aldehydes, amines, and trimethylphosphite using graphene oxide as catalyst.

An efficient, one-pot three component synthesis of highly functionalized tri- and tetrasubstituted thiophenes has been reported involving (het)aryl dithioesters as thiocarbonyl precursors. Thus, sequential base mediated condensation of readily available (het)aryl active methylene ketones with (het)aryl dithioesters followed by S-alkylation of the resulting enethiolate salts with activated halomethylene compounds and concurrent intramolecular aldol-type condensation of S-alkylated compounds affords substituted thiophenes in excellent yields. The methodology has also been extended for the synthesis of highly fluorescent push–pull substituted thiophene-5-acrylates by using bromocrotonate as the activated methylene alkylating agent.

A highly chemoselective intermolecular crossed acyloin condensation between aromatic aldehydes and trifluoroacetaldehyde ethyl hemiacetal has been developed under mild reaction conditions using N-heterocyclic carbene as a catalyst. A wide range of aromatic aldehydes bearing electron-withdrawing and -donating substituents underwent a smooth transformation to their corresponding trifluoromethyl containing acyloin derivatives in moderate to good yields.

Metal-ligand cooperation (MLC) plays an impor- tant role in catalysis. Systems reported so far are generally based on a single mode of MLC. We report here a system with potential for MLC by both amine-amide and aromati- zation-dearomatization ligand transformations, based on a new class of phosphino-pyridyl ruthenium pincer com- plexes, bearing sec-amine coordination. These pincer com- plexes are effective catalysts under unprecedented mild conditions for acceptorless dehydrogenative coupling of alcohols to esters at 358C and hydrogenation of esters at room temperature and 5 atm H2. The likely actual catalyst, a novel, crystallographically characterized monoanionic de-aromatized enamido-Ru II complex, was obtained by deprotonation of both the NH and the methylene proton of the N-arm of the pincer ligand.

This potentially useful method for biology-oriented synthesis does not require any catalyst and proceeds fast under mild conditions.

A highly efficient and atom-economic dual reaction manifold has been developed to synthesize 4H-thiopyran and 4,5-dihydrothiophene frameworks via regioselective intramolecular C–S fusion of α-allyl-β′-oxodithioesters. The ring size of the sulfur-heterocycles has been efficiently tuned by the use of two different catalytic systems. Palladium activates the Cδ–H of the allyl termini and facilitates the intramolecular Cδ–S coupling to furnish six-membered thiopyran skeletons exclusively. Conversely, the allylic double bond of the same substrate has been activated by BF3·Et2O to promote the Cγ–S cyclization leading to the formation of a five-membered dihydrothiophene nucleus.

Medicinally and biologically relevant imidazo-fused polyheterocycles are prepared in a one-pot three component reaction.

Starting from a broad range of 3,5-disubstituted phenols and aryl or alkyl substituted acetic acids this operationally simple strategy offers an efficient access to substituted chromen-4-one and isoflavone frameworks.

High yields of the products (III), (V), (VII), low catalyst loading, less reaction time, and simple workup are the prominent features of the introduced methodology.