Chemoenzymatic synthesis of boron-containing chiral amines and amides

The first application of lipases as catalysts to obtain optically active boron-containing amines and amides is described. We studied several reaction conditions to achieve the kinetic resolution of boron-containing amines via enantioselective acylation mediated by Candida antarctica lipase B (CAL-B). Excellent enantioselectivity (E >200) and high enantiomeric excess (up to >99%) of both the remaining amines and amides were obtained.     

1H NMR study of chiral recognition of amines by chiral Kemp's acid diamide

Chiral recognition by homochiral Kemp's acid diamide was studied by a ¹H NMR titration method. The diamide monoacid, prepared by amidation with enantiomerically pure (S)-α-methylbenzylamine, gave a large chemical shift change for five amines studied and showed good enantioselectivity toward cis-N-benzyl-2-aminocyclohexanemethanol.     

Synthesis and bioactivity evaluation of some novel sulfonamide derivatives

A simple and convenient method for the synthesis of biologically active sulfonamide derivatives was achieved. All the title compounds were characterized by spectral and elemental analysis. They were further screened in vitro for their abilities towards antibacterial, antifungal and antioxidant activities. The compound N,N'-(3,3′-dimethoxybiphenyl-4,4′-diyl)bis(4-fluorobenzenesulfonamide) (5b) and N-(3-(9H-carbazol-4-yloxy)-2-hydroxypropyl)-4-fluoro-N-isopropylbenzenesulfonamide (5e) exhibited good activity when compared to the standard bactericide, Chloramphenicol and fungicide, Ketoconazole respectively. The compounds (2S)-N-((2S,4S)-5-(4-Chloro-phenylsulfonamido)-4-hydroxy-1, 6-diphenylhexan-2-yl)-3-methyl-2-(2-oxotetrahydropyrim-idin-1(2H)-yl)butan-amide (4f) and (2S)-N-((2S,4S)-5-(4-fluorophenylsulfonamido)-4-hydroxy-1,6-diphenyl-hexan-2-yl)-3-methyl-2-(2-oxotetrahydropyrimidin-1(2H)-yl)bu-tana-mide (5f) exhibited good antioxidant activity when compared with standard antioxidant, Ascorbic acid.     

Synthesis and antifungal activities of some thiolane-triazole derivatives

As part of our search for active agents against systemic fungal infections, a new series of triazole compounds with a thiolane ring was synthesized. Their antifungal activities were investigated in vitro and in vivo. Some of these thiolanetriazoles showed promising activity, comparable to that of ketoconazole, against a mouse systemic Candida albicans infection, after oral or parenteral dosing.     

Synthesis and antifungal activity of some allylamine derivatives

Benzo- and mesitonitrile oxides react with allylamine to yield 5-aminomethyl-2-isoxazolines and open-chain N-substituted amidoximes. The allylamine derivatives were evaluated as potential antifungal and antibacterial agents. The N-allylbenzamidoxime 2a was found to be only moderately active against dermatophytes.     

Synthesis and study of some derivatives of cinchoninic acid

2-(4-Phenylquinolin-2-yl)cinchoninic and 2-(quinoxalin-2-yl)-5,6-benzocinchoninic acids have been synthesized. They have been subjected to decarboxylation and their chlorides and esters, amides, and anilides have been prepared. The spectral characteristics of the Cu(I) complexes of the derivatives synthesized have been obtained.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1536–1537, November, 1973.     

Synthesis, antiviral and antifungal bioactivity of 2-cyano-acrylate derivatives containing phosphonyl moieties

Alkyl 2-cyano-3-methylthio-3-phosphonylacrylates were synthesized by the reaction of alkyl 2-cyano-3,3-dimethylthioacrylates with dialkyl phosphites. The structures of the new compounds were characterized by elemental analyses, IR, 1H-, 13C- and 31P-NMR spectral data. These compounds were tested in vitro against pathogenic fungi, namely, Fusarium graminearum, Cytospora mandshurica and Fusarium oxysporum. Amongst all compounds, 2d and 2t were found to be effective against the tested fungi at 50 microg/mL. A half-leaf method was used to determine the in vivo protective, inactivation and curative efficacies of the title products against tobacco mosaic virus (TMV). Title compounds 2a and 2b were found to possess good in vivo curative, protection and inactivation effects against TMV with inhibitory rates at 500 mg/L of 60.0, 89.4 and 56.5 and 64.2, 84.2 and 61.2 %, respectively. To the best of our knowledge, this is the first report on the antiviral and antifungal activity of alkyl 2-cyano-3-methylthio-3-phosphonylacrylates.     

Theoretical study of the corrosion inhibition of some bipyrazolic derivatives: a conceptual DFT investigation

Corrosion inhibition of copper through six bipyrazolic compounds has been elucidated by means of density functional theory (DFT)-derived reactivity indexes. The DFT calculated parameters and experimental corrosion inhibition efficiency (IE%) indicate that their inhibition effect is closely related to the frontier orbital energies, polarizability, electronic chemical potential and global nucleophilicity. The quantum chemistry calculations were performed at the B3LYP/6-31G (d) level. The theoretical results, predicted using DFT-based reactivity indexes, are in good agreement with experimental outcomes.     

Preparation of functionalized primary chiral amines and amides via an enantioselective three-component synthesis of propargylamines

A general preparation of functionalized primary chiral amines and amides from propargylamines has been developed. The chirality is established by an enantioselective three-component reaction of an aldehyde, a terminal alkyne and a secondary amine in the presence of copper(I) bromide/Quinap as the catalytic system leading to chiral propargylamines in high yields and enantioselectivities. Functionalization and reduction leads to various primary amines and amides.     

Reactions of some benzofuran derivatives with amides,nitriles and hydrazines

When 6-acetoacetyl-5-methoxy- ( 1b ) and 5-acetoacetyl-6-methoxy-2,3-diphenylbenzofuran ( 2b ) were treated with cyanoacetamide, the corresponding pyridinecarbonitriles were obtained. Compounds 1b and 2b reacted with ethyl cyanoacetate in the presence of ammonium acetate to give the benzofuranyl-pyrone derivatives. This reaction, when carried out in presence of diethylamine, led to the formation of furochromones. Hydrazine hydrate, phenylhydrazine and semicarbazide hydrochloride reacted with 1b and 2b with the formation of the corresponding pyrazoles. The corresponding isoxazole derivatives were formed by the reaction of 1b and 2b with hydroxylamine hydrochloride.     

Catalytic enantioselective conjugate addition of aromatic amines to fumarate derivatives: asymmetric synthesis of aspartic acid derivatives

The catalytic enantioselective conjugate addition of aromatic amines to fumarate derivatives promoted by chiral palladium complexes is described. Treatment of aniline derivatives with fumaryl pyrrolidinone as Michael acceptor under mild reaction conditions afforded the corresponding chiral aspartic acid derivatives with excellent enantiomeric excesses (83–96% ee).     

Synthesis,DFT study,molecular docking and insecticidal evaluation of some pyrazole-based tetrahydropyrimidine derivatives

Abstract

The building block synthon, 1-(4-(1,3-diphenyl-1H-pyrazol-4-yl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl)ethan-1-one was efficiently synthesized by Biginelli reaction of 1,3-diphenyl-1H-pyrazole-4-carbaldehdye, acetylacetone, and thiourea and submitted to react with ethyl chloroacetate and chloroacetyl chloride under different conditions to afford some N-heterocycles integrated with pyrazole scaffold. Hydrazinolysis of the pyrimidinethione was studied under different conditions. The insecticidal activity for these compounds, DFT calculations, and docking were run and discussed. Some of them exhibited 100% mortality against Nilaparvata lugens and Mythimna separata.     

Synthesis and bioactivity of novel nitric oxide-releasing ursolic acid derivatives

A series of furoxan-based novel nitric oxide-donating ursolic acid(UA) derivatives(7a-f) were synthesized,and their cytotoxic activities against HepG2 cells in vitro were evaluated by MTT method.It was found that 7a-d and 7f showed more potent cytotoxic activities than control 5-fluorouracil and UA.     

Synthesis,characterization, POM analysis and antifungal activity of novel heterocyclic chalcone derivatives containing acylated pyrazole

Research on Chemical Intermediates - A series of heterocyclic chalcone derivatives (4a–h) were synthesized and characterized by IR, 1H and 13C NMR as well as MS. All the synthesized compounds...     

Cage-like amines in the synthesis and oxidation of camphor-10-sulfonic acid amides

Reactions of bicyclo[2.2.1]hept-5-en-exo- and -endo-2-ylmethanamines, exo-5,6-epoxybicyclo-[2.2.1]hept-exo-2-ylmethanamine, 1-(bicyclo[2.2.1]hept-2-yl)ethanamine, and 1-(1-adamantyl)ethanamine with camphor-10-sulfonyl chloride in chloroform in the presence of triethylamine gave the corresponding sulfonamides having two cage-like fragments. Stereoisomeric N-(bicyclo[2.2.1]hept-5-en-2-ylmethyl)camphor-10-sulfonamides were oxidized with peroxyphthalic acid generated in situ from phthalic anhydride and 50% hydrogen peroxide. The exo stereoisomer was thus converted into the corresponding 5,6-epoxy derivative, while the endo isomer gave rise to 4-(7,7-dimethyl-2-oxobicyclo[2.2.1]hept-1-ylmethyl)-4-azatricyclo[4.2.1.0^3,7]-nonan-exo-2-ol (substituted azabrendane). The structure of the synthesized camphor-10-sulfonamides was confirmed by IR and ¹H and ¹³C NMR spectra with the use of homo- (COSY) and heteronuclear ¹H-¹³C correlation techniques (HMQC, HMBC). Heterocyclization of sulfonamides of the norbornene series was also simulated by quantum-chemical calculations at the PM3 and BHandHLYP/6-31G(d) levels of theory.     

Zinc-catalyzed chemoselective reduction of tertiary and secondary amides to amines

General and convenient procedures for the catalytic hydrosilylation of secondary and tertiary amides under mild conditions have been developed. In the presence of inexpensive zinc catalysts, tertiary amides are easily reduced by applying monosilanes. Key to success for the reduction of the secondary amides is the use of zinc triflate and disilanes with dual Si-H moieties. The presented hydrosilylations proceed with excellent chemoselectivity in the presence of sensitive ester, nitro, azo, nitrile, olefins, and other functional groups, thus making the method attractive for organic synthesis.     

Diastereoselective electrochemical carboxylation of chiral alpha-bromocarboxylic acid derivatives: an easy access to unsymmetrical alkylmalonic ester derivatives

The diastereoselective electrochemical carboxylation of chiral N-(2-bromoacyl)oxazolidin-2-ones has been studied. This reaction was carried out by cathodic reduction of the C-Br bond, in the presence of carbon dioxide, followed by treatment with diazomethane. The yields and the diastereomeric ratio of the two epimeric alkylmalonic acid derivatives are strongly affected by various factors: solvent-supporting electrolyte system, temperature, electrode material, electrolysis conditions, oxazolidinone moiety. The higher yields (88%) were obtained starting from N-(2-bromopropionyl)-4R-phenyloxazolidin-2-one 1a, but with poor diastereoselectivity (61:39). The two epimers were easily separated by flash chromatography. The best results were achieved using a different chiral auxiliary: Oppolzer's camphor sultam. Starting from 1j a good yield in carboxylated product was obtained (80%) with excellent diastereoselectivity (98:2). These chiral alkylmalonic acid derivatives are valuable building blocks in the synthesis of molecules with biological activity and of chiral propane-1,3-diols derivatives.