Low catalyst loading enabled organocatalytic synthesis of chiral bis-heterocyclic frameworks containing pyrazole and isoxazole.

The organocatalytic asymmetric synthesis of enantiopure bis-heterocyclic molecules containing pyrazole and isoxazole under mild reaction conditions has been reported a low-catalyst loading Michael addition reaction of pyrazolyl nitroalkenes with 1,3-dicarbonyl derivatives. 4-Substituted pyrazole derivatives were obtained in 60-87% yields and with 82-97% ee. These pyrazolyl derivatives are further transformed into chiral bis-heterocyclic derivatives in up to 82% yields and up to 99% ee.

Toxic effects of purified phenolic compounds from Acacia nilotica against common cutworm.

Phenolics are the most abundant secondary metabolites of plants that are widely distributed in the plant kingdom. In the last few years, the development and identification of phenolic compounds from various plants have become a major area of the environment and health-related research. In the present study, different phenolic compounds were purified from the bark of the medicinally important plant Acacia nilotica which is rich in polyphenols and were evaluated for their insecticidal potential against a polyphagous pest, Spodoptera litura (Fab.

Arenesulfonyl indole: new precursor for diversification of C-3 functionalized indoles.

Arenesulfonyl indoles, bearing a good leaving group, are effective precursors for vinylogous imine intermediates which are generated under basic conditions. This intermediate can readily react with other nucleophilic reagents to obtain C-3 substituted indole derivatives. In the last few years, a plethora of exciting synthetic applications of this substrate have been exploited.

Recent advances in the catalytic synthesis of 3-aminooxindoles: an update.

3-Substituted-3-aminooxindoles are versatile scaffolds and they are common core structural motifs found in many natural products and biologically active compounds. In the last few years, a variety of synthetic methodologies have been developed for the synthesis of this moiety. In this review, we are presenting the recent advances in the catalytic synthesis of 3-aminooxindole derivatives.

Organocatalytic enantioselective conjugate addition of pyrazolin-5-ones to arylomethylidene malonates.

An efficient asymmetric organocatalytic conjugate addition reaction of pyrazolin-5-ones with arylomethylidene malonates has been successfully developed by employing bifunctional Cinchona derived thiourea organocatalysts. The protocol provides straightforward access to pyrazole substituted scaffolds in good yields with high stereocontrol.

Phenanthridine-Fused Tetracyclic Ring System: Metal-Free Diastereoselective Modular Construction of Highly Constrained Polyheterocycles via Post-Ugi Tandem Modifications.

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 reactions in a single operation. The transformation is mild and operationally simple, which provides architecturally complex polycyclic heterocycles with high diastereoselectivity.

Enantioselective 1,4-Michael addition reaction of pyrazolin-5-one derivatives with 2-enoylpyridines catalyzed by Cinchona derived squaramides.

The bifunctional nature of the cinchonidine squaramides has been successfully employed to catalyze the enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones with 2-enoylpyridines under mild reaction conditions. Through this methodology, a broad range of optically active heterocyclic derivatives bearing both pyrazole and pyridine motifs have been synthesized in yields up to 88% and enantiomeric excess up to 96%.

Catalytic synthesis of 3-aminooxindoles via addition to isatin imine: an update.

3-Substituted-3-aminooxindoles have attracted the attention of organic chemists since they have a common core structural motif found in many natural products and biologically active compounds. During the past six years, the new synthetic methodologies for the synthesis of this moiety have shown rapid growth. Thus, an update of our previous review has become necessary and this review includes the literature on this topic, covering the reactions of isatin imine explored in various organic transformations catalyzed by metals and organocatalysts.

Catalyst-Controlled Structural Divergence: Selective Intramolecular 7-endo-dig and 6-exo-dig Post-Ugi Cyclization for the Synthesis of Benzoxazepinones and Benzoxazinones.

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 afford family of six-membered benzoxazinones.

Journey Heading towards Enantioselective Synthesis Assisted by Organocatalysis.

This personal account summarizes the design of various organocatalysts derived from amino acids and Cinchona alkaloids and their applications in enantioselective carbon-carbon and carbon-nitrogen bond formation reactions. This account begins with the short description of the background of asymmetric organocatalysis. Various types of reactions like aldol reaction, Michael reaction, aza-Henry reaction, Morita-Baylis-Hillman reaction are described in this account.

Bioresolution of racemic phenyl glycidyl ether by a putative recombinant epoxide hydrolase from Streptomyces griseus NBRC 13350.

In order to produce enantiomerically pure epoxides for the synthesis of value-added chemicals, a novel putative epoxide hydrolase (EH) sgeh was cloned and overexpressed in pET28a/Escherichia coli BL21(DE3). The 1047 bp sgeh gene was mined from Streptomyces griseus NBRC 13350 genome sequence. The recombinant hexahistidyl-tagged SGEH was purified (16.

α,α-Dicyanoolefins: versatile substrates in organocatalytic asymmetric transformations.

α,α-Dicyanoolefins have emerged as versatile reactants, finding use as vinylogous nucleophiles, Michael acceptors and dienophiles in a variety of organic reactions. In the last few years, the reactivity of α,α-dicyanoolefins has been explored in various asymmetric transformations catalyzed by organocatalysts. In this review, we are presenting the recent advances in asymmetric organocatalytic transformations involving α,α-dicyanoolefins.

Maleimide as an efficient nucleophilic partner in the aza-Morita-Baylis-Hillman reaction: synthesis of chiral 3-substituted-3-aminooxindoles.

A highly enantioselective Morita-Baylis-Hillman reaction of maleimides with isatin derived ketimines has been developed to obtain enantiomerically enriched 3-substituted-3-aminooxindoles using β-isocupreidine as an organocatalyst. Maleimide acting as a nucleophile provides products with up to 99% ee.

Trigger factor assisted folding of the recombinant epoxide hydrolases identified from C. pelagibacter and S. nassauensis.

Epoxide hydrolases (EHs), are enantioselective enzymes as they catalyze the kinetic resolution of racemic epoxides into the corresponding enantiopure vicinal diols, which are useful precursors in the synthesis of chiral pharmaceutical compounds. Here, we have identified and cloned two putative epoxide hydrolase genes (cpeh and sneh) from marine bacteria, Candidatus pelagibacter ubique and terrestrial bacteria, Stackebrandtia nassauensis, respectively and overexpressed them in pET28a vector in Escherichia coli BL21(DE3). The CPEH protein (42kDa) was found to be overexpressed as inactive inclusion bodies while SNEH protein (40kDa) was found to form soluble aggregates.

Primary-tertiary diamine-catalyzed Michael addition of ketones to isatylidenemalononitrile derivatives.

Simple primary-tertiary diamines easily derived from natural primary amino acids were used to catalyze the Michael addition of ketones with isatylidenemalononitrile derivatives. Diamine 1a in combination with D-CSA as an additive provided Michael adducts in high yield (up to 94%) and excellent enantioselectivity (up to 99%). The catalyst 1a was successfully used to catalyze the three-component version of the reaction by a domino Knoevenagel-Michael sequence.

Recent developments on thiourea based anticancer chemotherapeutics.

The recent emergence of anticancer activity of thiourea derivatives have inspired the medicinal chemist to design and synthesize new thiourea derivatives. These thiourea based anticancer chemotherapeutics inhibit cancer propagation by acting as inhibitors of topoisomerase, protein tyrosine kinase, somatostatin agonists, sirtuins, and carbonic anhydrase (CA). This review summarizes the recent developments on the thiourea based anticancer chemotherapeutics.

Organocatalytic asymmetric Friedel-Crafts reaction of sesamol with isatins: access to biologically relevant 3-aryl-3-hydroxy-2-oxindoles.

The Friedel-Crafts reaction of electron-rich phenols with isatins was developed by employing bifunctional thiourea-tertiary amine organocatalysts. Cinchona alkaloid derived thiourea epiCDT-3 a efficiently catalyzed the Friedel-Crafts-type addition of phenols to isatin derivatives to provide 3-aryl-3-hydroxy-2-oxindoles 7 and 9 in good yield (80-95 %) with good enantiomeric excess (83-94 %). Friedel-Crafts adduct 7 t was subjected to a copper(I)-catalyzed azide-alkyne cycloaddition to obtain biologically important 3-aryl-3-hydroxy-2-oxindole 11 in good enantiomeric excess and having a 1,2,3-triazole moiety.

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach.

Ball-milling and pestle and mortar grinding have emerged as powerful methods for the development of environmentally benign chemical transformations. Recently, the use of these mechanochemical techniques in asymmetric organocatalysis has increased. This review highlights the progress in asymmetric organocatalytic reactions assisted by mechanochemical techniques.

Asymmetric organocatalytic addition reactions of maleimides: a promising approach towards the synthesis of chiral succinimide derivatives.

Recent progress in asymmetric organocatalysis has led to the development of several asymmetric transformations that employ various substrates. Among these substrates, maleimides have emerged as excellent Michael acceptors, dienophiles, and dipolarophiles. In this Focus Review we highlight the advances in the asymmetric synthesis of succinimide derivatives through asymmetric organocatalytic addition reactions of maleimides.

Bioresolution of benzyl glycidyl ether using whole cells of Bacillus alcalophilus.

The incubation of whole Bacillus alcalophilus cells grown on a mineral supplemented medium (MSM) containing 1% (w/v) sucrose as carbon source, 1.2% (w/v) tryptone as nitrogen source at pH 6.5 and temperature 30 °C in 24 h kinetically resolved benzyl glycidyl ether (1 mg/ml) to provide (S)-benzyl glycidyl ether with 30% ee and (R)-3-benzyloxypropane-1,2-diol with 40% ee.

Asymmetric syn-selective direct aldol reaction of protected hydroxyacetone catalyzed by primary amino acid derived bifunctional organocatalyst in the presence of water.

A new series of water compatible primary-tertiary diamine catalysts derived from natural primary amino acids bearing a hydrophobic side chain have been synthesized. These new primary-tertiary diamine-Brønsted acid conjugates bifunctional organocatalysts efficiently catalyzes the asymmetric direct syn selective cross-aldol reaction of different protected hydroxyacetone with various aldehydes in high yield (94%) and high enantioselectivity (up to 97% ee of syn) and dr of 91 : 9 (syn/anti) under mild reaction conditions.

Enantiocomplementary reduction of 3-phenylthiopropan-2-one by Bacillus sp.: effect of medium components.

The enantioselectivity of the enzymes responsible for reduction of prochiral compound 3-phenylthiopropan-2-one was dependent on the concentration of yeast extract and glucose in the growth medium. Low concentrations of yeast extract (0.1-0.

Comparative studies on potential of consortium and constituent pure bacterial isolates to decolorize azo dyes.

The decolorization potential of the consortium HM-4 constituted by mixing four laboratory isolates identified as Bacillus cereus (BN-7), Pseudomonas putida (BN-4), Pseudomonas fluorescens (BN-5) and Stenotrophomonas acidaminiphila (BN-3) was compared with that of individual isolates. Six different azo dyes viz., C.