Silver-Mediated Mild Oxidation of Nitrogen-Containing Heteroaryl-2-methanols to Esters

Oxidation of nitrogen-containing heteroaryl-2-methanols to esters with Ag₂O and isopropyl iodide is reported. This methodology is very mild and can tolerate many functional groups.     

Promiscuous Candida antarctica lipase B-catalyzed synthesis of β-amino esters via aza-Michael addition of amines to acrylates

An efficient protocol for the regioselective aza-Michael addition of amines with acrylates using CaL B as a biocatalyst at 60 °C has been developed. The reaction is applicable to a wide variety of primary and secondary amines with different acrylates to synthesize the corresponding β-amino esters with good yields. An alternative route for the synthesis of higher β-amino esters through the additional transesterification step is also studied and was found effective.     

Microbial screening of novel synthesized formazans having amide linkagesΦ

Formazans 5(a‐j) have been prepared by the condensation between schiff base 3 and diazonium salt of substituted 2‐amino benzothiazole 4(a‐j) . The intermediate schiff base 3 was synthesized by the condensation of p‐nitrobenzolyhydrazide 1 with thiophene‐2‐aldehyde 2 . All the compounds have been screened for their antifungal activity against Candida albicans (ATCC‐64550), Candida krusei (ATCC‐14243) and Candida parapsilosis (ATCC‐22019) and antibacterial activity against Escherchia coli (ATCC‐6538), Staphylococcus aureus (ATCC‐6538), Pseudomonas aeruginosa (ATCC‐1539) and Bacillus substilis (ATCC‐6633). The structures of the synthesised compounds 5(a‐j) have been characterized on the basis of their elemental analysis and spectral data (UV, IR, ¹H NMR, ¹³C NMR and Mass).     

Photochemical reactions of 1-ferrocenyl-4-phenyl-1,3-butadiyne with Fe(CO)5 and CO

Photolysis of a hexane solution containing ironpentacarbonyl, 1-ferrocenyl-4-phenyl-1,3-butadiyne at low temperature yields six new products: [Fe(CO)₂{η²:η²-PhCCCC(Fc)C(CCPh)C(Fc)Fe(CO)₃}-μ-CO] (1), [Fe₂(CO)₆{μ-η¹:η¹:η²:η²-PhCCCC(Fc)-C(O)-C(Fc)CCCPh}] (2), [Fe₂(CO)₆{μ-η¹:η¹:η²:η²-FcCC(CC Ph)-C(O)-C(Fc)CCCPh}] (3), [Fe₂(CO)₆{μ-η¹:η¹:η²:η²-FcCCCC(Fc)-C(O)-C(Fc)CCCPh}] (4), [Fe(CO)₃{μ-η²: η²-[FcCC(CCPh)C(CCPh)C(Fc)}CO] (5) and [Fe(CO)₃{μ-η²: η²-[FcCC(CCPh)C(CCPh)C(Fc)}CO] (6) formed by coupling of acetylenic moieties with CO insertion on metal carbonyl support. In presence of CO, formation of another new product 2,5-bis(ferrocenyl)-3,6-bis(tetracarbonylphenylmaleoyliron)quinone (7) was observed which on further reaction with ferrocenylacetyene gave the quinone, 2,5-bis(ferrocenyl)-3,6-bis(ethynylphenyl)quinone (8). Structures of 1-5 and 8 were established crystallographically.     

A convenient,rapid microwave assisted synthesis of some novel 3-[(4-chloro-3-methylphenoxy)methyl]-6-aryl-5,6-dihydro-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles using acidic alumina

A facile synthesis of 3-[(4-chloro-3-methylphenoxy)methyl]-6-aryl-5,6-dihydro-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 3a–n has been achieved by microwave promoted condensation of 3-mercapto-4-amino-5-[(4-chloro-3-methylphenoxy)methyl]-4H-1,2,4-triazole 1 with various aromatic aldehydes 2a–n in presence of catalytic amount of p-TsOH (para-toluenesulphonic acid). The structures of 3a–n are supported by IR and ¹H and ¹³C NMR spectral data.     

Development of drug intermediates by using direct organocatalytic multi-component reactions

Novel, economic and environmentally friendly one-pot three-component Knoevenagel/hydrogenation (K/H) and four-component Knoevenagel/hydrogenation/alkylation (K/H/A) reactions of ketones, CH-acids, dihydropyridines and alkyl halides using proline and proline/metal carbonate catalysis, respectively, have been developed. Many of the products of these K/H and K/H/A reactions have direct applications in pharmaceutical chemistry.     

Characterization of the tryptophan residues of human placental ribonuclease inhibitor and its complex with bovine pancreatic ribonuclease A by steady-state and time-resolved emission spectroscopy

Human placental ribonuclease inhibitor (hRI) containing six tryptophan (Trp) residues located at positions 19, 261, 263, 318, 375, and 438 and its complex with RNase A have been studied using steady-state and time-resolved fluorescence (298 K) as well as low-temperature phosphorescence (77 K). Two Trp residues in wild-type hRI and also in the protein-protein complex with RNase A are resolved optically. The accessible surface area values of Trp residues in the wild-type hRI and its complex and consideration of inter-Trp energy transfer in the wild-type hRI reveal that one of the Trp residues is Trp19, which is located in a hydrophobic buried region. The other Trp residue is tentatively assigned as Trp375 based on experimental results on wild-type hRI and its complex. This residue in the wild-type hRI is more or less solvent exposed. Both the Trp residues are perturbed slightly on complex formation. Trp19 moves slightly toward a more hydrophobic region, and the environment of Trp375 becomes less solvent exposed. The complex formation also results in a more heterogeneous environment for both the optically resolved Trp residues.     

Hyaluronan-based glycoclusters as probes for chemical glycobiology

A strategy is described for the synthesis of β-(1,3)-GlcA-GlcNAc dimeric and tetrameric glycoclusters through the conjugation of disaccharide groups onto a diaminodiamide aromatic scaffold by reductive amination.     

Homogeneous Operators, Jet Construction and Similarity

In this paper we show, starting with the jet construction, how to construct all the irreducible homogeneous operators in the Cowen–Douglas class B_n(mathbb D){mathrm {B}_n(mathbb {D})} whose associated representations are multiplicity-free.     

High-performance thin-layer chromatography (HPTLC) method development and validation for the estimation of curcumin and cineole

JPC – Journal of Planar Chromatography – Modern TLC - Curcumin and cineole are phytochemicals which have shown synergistic effects in allergic rhinitis (AR). The aim of the current work...