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An efficient one-pot synthesis of a series of diversely functionalized trisubstituted 4(5)het(aroyl)-2,5(4)-het(aryl)/alkylimidazoles from readily available 1,3-bishet(aryl)monothio-1,3-diketones has been reported. This novel sequential one-pot, three step protocol, wherein three new carbon nitrogen bonds are formed in contiguous fashion, involves in situ generation of enaminones by reaction of monothio-1,3-diketones with α-substituted methylamines, followed by their α-nitrosation with sodium nitrite and subsequent base mediated intramolecular heterocyclization of the resulting α-hydroxyiminoimines to trisubstituted imidazoles in high yields under mild conditions. These newly prepared 4(5)-het(aroyl)-5(4)-het(aryl)/alkylimidazoles are shown to exist as tautomeric mixture, however, their subsequent alkylation with methyl iodide in the presence of potassium carbonate affords 1-N-methy-2,5-bishet(aryl)-4-het(aroyl)imidazoles in highly regioselective fashion in most of the cases. Synthesis of few 4(5)-(2-hydr...

An efficient route to multisubstituted indoles has been developed through intramolecular oxidative C–H activation-amination of readily available 2-(het)aryl-3-(het)aryl/alkyl-3-(het)aryl/acylaminoacrylonitrile/enaminone precursors in the presence of either palladium acetate/cupric acetate catalytic system under oxygen atmosphere or palladium acetate/silver carbonate in the presence of pivalic acid as additive. The method is compatible with a diverse range of substituents on the aryl ring as well as at the 2- and 3-positions of the indole ring. The versatility of this method was further demonstrated by elaborating it for the synthesis of heterofused pyrroles such as thieno[2,3-b]pyrroles, thieno[3,2-b]pyrroles, pyrrolo[2,3-b]indoles, and pyrrolo[2,3-b]pyridines in good yields. Probable mechanisms for the formation of these indoles have been suggested.

Both enantiomers of cis- and trans-fused 3,4,4a,8a-tetrahydro-2H,5H-pyrano[2,3-b]pyran-7-carboxylates have been obtained in high diastereoselectivities and enantioselectivities from the same starting materials using a tandem inverse-electron-demand hetero-Diels-Alder/oxa-Michael reaction catalyzed by modularly designed organocatalysts (MDOs). Diastereodivergence was achieved in these reactions through the direct control of the stereochemistry of the bridgehead atoms of the fused ring using new MDOs self-assembled from both enantiomers of proline and cinchona alkaloid thiourea derivatives.

Quinidine-derived thiourea derivative (Ia) is an efficient catalyst for the asymmetric aldol reaction of β,γ-unsaturated α-ketoesters (II) with acetophenones (III), whilst similar catalyst (Ib) is successfully applied for the synthesis of 2-hydroxy-1,4-diones (VII) via aldol reaction of arylglyoxal hydrates (V) with cycloalkanones (VI).

The use of a bifunctional quinidine thiourea catalyst (QUI) allows the synthesis of Michael addition products in excellent yields with high enantioselectivities up to 99% ee.

A convenient and practical approach for the total synthesis of naturally occurring lactone synargentolide-B has been accomplished in 14 steps from the commercially available l-ascorbic acid and d-ribose involving Bestmann–Ohira reaction, zinc mediated allylation, ring closing-metathesis, and cross-metathesis reactions. The highlight of our strategy describes a one-pot reaction involving stereoselective addition of allylzinc reagent and selective reduction of terminal alkyne to obtain the key advanced intermediates.

A series of N-heterocyclic carbene (NHC) supported gold(I) complexes were synthesized, characterized in solution as well as in the solid state, and examined as precatalysts for 1,6-enyne cycloisomerization reactions. The product mixtures obtained for a variety of 1,6-enyne isomerizations were governed primarily by the electronic properties of the aforementioned precatalysts. In particular, precatalysts containing electronic-rich NHC ligands showed increased selectivity for bicyclic products, whereas analogous precatalysts supported by electron-deficient NHCs preferentially afforded olefinic products.

CuFe2O4 is used as inexpensive, non-toxic, and magnetically separable catalyst for the reaction of arylsulfinic acid salts with organohalides or boronic acids to yield sulfones with a wide range of functional group tolerance.

A convenient and practical InCl 3 catalyzed three-component reaction of 4-hydroxy coumarin/1,3 diones, aromatic aldehyde, and secondary amine for the synthesis of α-benzylamino coumarins and diketones in good yields has been reported.

A new protocol for the dehydrogenation of dihydropyridazin-3(2H)-one has been carried out by catalytic amount of iodine in dimethyl sulphoxide in good yield with easy workup.

A simple and selective deallylation of aryl/alkyl ether and esters, which includes an easy work-up and a readily available and inexpensive catalyst, is presented.

The compounds (IV), (V), and (VII) are synthesized by using facile, simple and well-versed synthetic methodologies.

Condensation of o-phenylenediamine with chalcones (II) provides the target compounds (12 examples) which are evaluated for antifungal and antibacterial activity.

A new class of sulfone-linked bis(heterocycles) having two different heterocyclic rings is synthesized.

Exploiting lanthanide chemistry and 1,3-dipolar cycloaddition technology, title compounds (V) are prepared as a new class of substituted pyrroles.

4-Dimethylaminopyridine-catalyzed reaction of mixed carbonates 3 with N-protected amino acids 4 gave the corresponding active esters 5-9, from which dipeptides 11-18 were synthesized by aminolysis with amino acids 10

A new convenient route for asymmetric synthesis of the epoxy fragment of azinomycin B by Sharpless asymmetric epoxidation of secondary allylic alcohol is described.

The absolute configuration of bruceine H was determined to be 1S, 5S, 7R, 8R, 9R, 10S, 11R, 12S, 13R, 14R, 15R by means of X-ray analysis of 15-O-acetylbruceine H 22-p-bromobenzoate

Allyl isopropenyl dicarbonate (1) reacts with carboxylic acids in the presence of 4-dimethylaminopyridine(DMAP) catalyst to give allyl esters in high yields under mild conditions such as in a near-neutral medium at room temperature.

Reactions of the title compounds with several nucelophiles suggested that the ring oxygen atom (O-5) accelerated the reactivity of the nitro alkene moiety, but scarcely affected the stereoselectivity of the nucleophilic attack.

Neohancoside C (1) is a new phenol glycoside isolated from Cynanchum hancockianum, which is a Chinese folk medicine having antitumor activity. The synthesis of 1, 2-acetylphenyl β-D-xylopyranosyl-(1→6)-β-D-glucopyranoside, was achieved by phase-transfer-catalyzed glycosidation using glycosyl bromide.

The first total synthesis of Mer-N5075A (1), a new potential HIV-I protease inhibitor produced from Streptomyces Chromofuscus, was achieved. The synthetic method is available for Mer-N5075A analogues such as α-MAPI (2), GE20372 A (4) and other chemcally modified compounds.

Neohancosides A (1) and B (2) are monoterpene diglycosides isolated from Cynanchum hancockianum , which is a Chinese folk medicine having antitumor activity. First total synthesis of 1 and 2 , (3 R )-linaloyl and (3 R )-8-hydroxylinaloyl 3- O - β -d-xylopyranosyl-(1 → 6)-β-d-glucopyranosides were achieved stereoselectively using fluoride 12b as a glycosyl donor. The asymmetry of C-3 in 1 and 2 was introduced efficiently by separating diasteremers of (3 R ), (3 S )-linaloyl and (3 R ), (3 S )-8-benzoyloxylinaloyl 3- O -2,3,4-tri- O -benzoyl-β-d-glucopyranoside, 19 and 21 and 20 and 22 , respectively. Absolute configurations of 1 and 2 were determined by enzymatic degradation of synthetic intermediates 33 and 34 .

Pyrazolo[3,4-d]thiazolo[3,2-a]pyrimidin-4-one derivatives have been prepared by cyclocondensation of ethyl 2-cyano-3,3-bis(methylthio)prop-2-enoate with 2-amino-4-(substitutedphenyl)thiazole to give 3-cyano-2-methylthio-4-oxo-4H-6-(substitutedphenyl)thiazolo[3,2-a]pyrimidin (2a–j) and further reacting with hydrazine hydrate to yield the target compounds (3a–j). The chemical structure of the compounds was confirmed by IR and 1H NMR spectral data. All the compounds of the series have been screened for their antibacterial and antifungal activity studies. The result revealed that all compounds showed significant antimicrobial activity.

Methyl and tert -butyl ( E -)-(pyrrolidin-2-ylidene)glycinates 3a and 3b were efficiently and stereoselectively synthesized from 2, 3, 5-tri- O -benzylarabinose using Horner-Emmons olefination of arabinal 9 and phosphorylglycine ester and intramolecular 1, 3-dipolar cycloaddition reaction of azide and olefin as the key reactions.

Neat formic acid alone efficiently N-formylates carbazoles, 3-alkylindoles, diphenylamine and even moderately weak nucleophilic anilines to furnish the corresponding N-formyl derivatives in 72--87% yields.

A new class of bis heterocycles-sulfone linked pyrazolyl oxadiazoles and thiadiazoles were developed from Z-styrylsulfonylacetic acid. The pyrazolyl thiadiazoles exhibited excellent antimicrobial activity whereas pyrazolyl oxadiazoles displayed good antioxidant activity.

Several 1-(4-(4'-chlorophenyl)-2-thiazolyl)-3-aryl-5-(2-butyl-4-chloro-1H-imidazol-5yl)-2-pyrazoline derivatives were prepared by the base catalyzed treatment of appropriate chalcones with 4-(4'-chlorophenyl)-2-hydrazino-thiazole in poly (ethylene glycol) (PEG-400) as an alternative reaction solvent. All the synthesized compounds were tested for their antimicrobial activities against Escherichia coli (MTCC 2939), Salmonella typhi (MTCC 98), Staphylococcus aureus (MTCC 96), Bacillus subtilis (MTCC 441), Aspergillus niger (MTCC 281), Trichoderma viridae (MTCC 167), Penicillium chrysogenum (MTCC 160), Fusarium moniliforme (MTCC 156) and Candida albicans (MTCC 183). Most of the compounds showed potent antibacterial and antifungal activity.

A new class of sulfone-linked bis heterocycles, methyl-3-(4'-aryl-1'H-pyrazol-3'-ylsulfonyl)-4-aryl-3H-pyrrole-3-carboxylate (8), methyl-3-(1'-phenyl-3',5'-diaryl-1'H-pyrazol-4'-ylsulfonyl)-4-aryl-3H-pyrrole-3-carboxylate (9) and methyl-3-(3',5'-diarylisoxazol-4'-ylsulfonyl)-4-aryl-3H-pyrrole-3-carboxylate (10) were prepared by the regioselective reaction of methyl-3-aryl-2-(E-arylethenesulfonyl)acrylate (2) with tosylmethyl isocyanide followed by fuctionalization of olefin moiety with 1,3-dipolar reagents. The lead compounds were tested for their antimicrobial activity.

A new class of bis heterocycles, oxazolyl/thiazolyl selenadiazoles, thiadiazoles and diazaphospholes were prepared from phenacylsulfonylacetic acid methyl ester and tested for their antimicrobial and antioxidant properties.

The Michael acceptors, l-arylsulfonyl-2-styrylsulfonylethenes have been used as synthons to develop bis pyrroles, pyrrolyl pyrazolines and pyrrolyl isoxazolines by 1,3-dipolar cycloaddition of tosylmethyl isocyanide, nitrile imines and nitrile oxides.

A new class of 2-oxazolines and 2-thiazolines 9/10 and 13/14 are prepared by base promoted cyclization of 3-aryl-N-(2-hydroxyethyl)-4-(arylsulfonyl)butanamide/3-aryl-S-(2-aminoethyl)-4-(arylsulfonyl)butanethioates with NaH in THF. 9/10 and 13/14 are also obtained by one pot methodology using samarium(III) chloride.