Separation of 4C-Substituted Pyrrolidin-2-One Derivatives on Amylose-Based Chiral Stationary Phases

Chromatographia - Our previous studies concerning the enantioseparation of 4C-substituted pyrrolidin-2-one derivatives on coated polysaccharide-based chiral stationary phases have shown that...     

Enantioseparation of 4C-Substituted Pyrrolidin-2-One Derivatives on Polysaccharide and Macrocyclic Glycopeptide Chiral Stationary Phases

Chromatographia - To extend our previous studies concerning the enantioseparation of 4C-substituted pyrrolidin-2-one derivatives on polysaccharide-based chiral stationary phases with...     

New isosteres of (R)-2-methylhomoserine and (R)-2-methylaspartic acid by alkylation of a chiral imine leading stereoselectively to a quaternary stereogenic center

Imines obtained from either chiral 3-amino-4-silyloxymethylpyrrolidin-2-one 5a or 5b underwent alkylation to give, in good yield and total stereoselection, the corresponding 3,3,4-trisubstituted pyrrolidin-2-ones 8a–d where both the amino and the silyloxymethyl groups lie cis to each other, as shown by ¹H NMR spectroscopic data and NOE experiments. By removal of both the imino group and the chiral inducer from 8b, the pyrrolidin-2-one 12, an isostere of (R)-2-methylhomoserine 2 and the pyrrolidin-2-one 14, an isostere of (R)-2-methylaspartic acid 4 were obtained straightforwardly.     

A novel conformationally restricted analogue of 3-methylaspartic acid via stereoselective methylation of chiral pyrrolidin-2-ones

Conformationally restricted analogues of β-methylaspartic acid were easily prepared starting from chiral N-protected trans-3-amino-4-methoxycarbonyl pyrrolidin-2-ones. The key step of the synthesis was the methylation reaction at C-4, proceeding with high diastereoselection syn to the protected amino group lying at C-3 of the pyrrolidin-2-one ring.     

Synthesis and Crystal Structure of Trans-4-[ （5-（ 2,4-Dichlorophenoxy）-3-methyl-1-phenyl-1H-pyrazol-4-yl）methyleneamino]-1,5-dimethyl-2-phenyl-l,2-dihydropyrazol-3-one

The title compound trans-4-[（5-（2,4-dichlorophenoxy）-3-methyl- 1-phenyl-1H-pyrazol-4-yl）methyleneamino]- 1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one 3 （C28H23Cl2N5O2, Mr = 532.41） has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P1- with a = 8.9438（4）, b = 11.6065（5）, c = 14.2215（6）A, α = 112.566（1）, β = 92.324（2）, γ = 102.91（1）°, V= 1315.65（10） A^3, Z = 2, Dc = 1.344 g/cm^3,μ（MoKa） = 0.282 mm^-1, λ = 0.71073 A, F（000） = 552, the final R = 0.0587 and wR = 0.1578 for 5071 observed reflections （I 〉 2σ（I））. X-ray analysis reveals that the product is a thermodynamically stable trans isomer. Intra- and intermolecular C（ 12）-H（12）…O（1） and C（28）-H（28）...O（1）# 1 hydrogen bonds were observed in the title compound.     

Synthesis and Crystal Structure of 3,3 ＇-（2,2 ＇-（E thane- 1,2-diylbis（oxy） ） bis（ethane- 2,1- diyl））bis（2-（4-chlorophenylamino）quinazolin-4（3H）-one）

The title compound 3,3＇-（2,2＇-（ethane-1,2-diylbis（oxy））bis（ethane-2,1-diyl））bis（2- （4-chlorophenylamino）quinazolin-4（3H）-one） 3 （C34H30CI2N604, Mr = 657.54） has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction analysis. It crystallizes in space group P1 with a = 9.9185（8）, b = 10.6124（9）, c = 15.4064（13） A, α = 92.896（2）,β = 103.813（2）, γ= 94.635（2）°, V= 1565.5（2） A3, Z = 2, Dc = 1.395 g/cm^3,μ = 0.257 mm^-1, F（000） = 684, the final R = 0.0580 and wR = 0.1284 for 3400 observed reflections （I〉 2σ（I）. It remains triclinic in the crystal. Intra- and intermolecular N（3）-H（3A）…O（2）, N（6）-H（6A）…O（3） and C（19）-H（19A）…O（4） #1 （#1： 1-x, 1-y, -z） hydrogen bonds are observed in the title compound. A two-dimensional chain network is formed from the dimmers and intermolecular π-π interactions in the crystal structure. This open network has solvent-accessible voids （10A3）.     

Synthesis of novel pyrrolidin-2-ones: γ-aminobutyric acid cyclic analogues

Some new N-substituted pyrrolidin-2-ones, cyclic analogues of baclofen and of 3-(5-methoxybenzo-[b]furan-2-yl)-γ-aminobutyric acid, have been prepared and characterized, starting from 4-(4-chlorophenyl)-pyrrolidin-2-one and 4-(5-methoxybenzo[b]furan-2-yl)pyrrolidin-2-one.     

Synthesis of 1-(2-Methyl-1,2,3,4-tetrahydroquinolin-4-yl) pyrrolidin-2-ones from Anilines and N-Vinyl Pyrrolidin-2-one Through Imino Diels–Alder Reaction Using 4-Nitro Phthalic Acid as Catalyst

Aryl amines react smoothly and efficiently with N-vinyl pyrrolidin-2-one in the presence of 4-nitro phthalic acid in acetonitrile to afford the corresponding 1-(2-methyl-1,2,3,4-tetrahydroquinolin-4-yl)pyrrolidin-2-ones in good yields.     

Asymmetric synthesis of 5-(1-hydroxyalkyl)-5-methyl-5H-furan-2-ones

The reactivity of 5-methyl-4-(pyrrolidin-1-yl)-5H-furan-2-one with aldehydes and with acyl chlorides followed by reduction was studied. The aldol condensation gave predominantly the anti aldol product when the acylation-reduction sequence led exclusively to the syn product. The use of a chiral pyrrolidine, (S)-2-methoxymethylpyrrolidine (SMP), allowed the synthesis of enantio-enriched compounds, the acylation-reduction leading to the (R,R) addition product.     

Ferroelectric liquid crystals with fluoro- and aza-fluorenone cores: the effect of stereo-polar coupling

The chiral fluorenone mesogens (R)-1-fluoro-2-(2-octyloxy)-7-(4-undecyloxybenzoyloxy)fluoren-9-one (2) and (R)-2-(2-octyloxy)-7-(4-undecyloxybenzoyloxy)-3-azafluoren-9-one (3) were synthesized using a combined ortho-directed and remote metalation strategy, which also incorporates a Suzuki-Miyaura crosscoupling step. These compounds form chiral SmC* liquid crystal phases with reduced polarizations (P _o) of +475 and +332 nC cm^-2 at 10 K below the Curie point, respectively. These values are considerably larger than that previously reported for the unsubstituted fluorenone (R)-2-(2-octyloxy)-7-(4-undecyloxybenzoyloxy)fluoren-9-one (1), which is +111 nC cm^-2 at 10 K below the Curie point. Molecular modelling based on the Boulder model suggests that the larger polarizations result from a conformational bias of the fluorenone core dipole moment along the polar axis of the SmC* phase caused by stereo-polar coupling with the chiral 2-octyloxy side chain.     

Synthesis of N-acyl-2-pyrrolidinones from the corresponding N-acyl-GABA derivatives

In this work, the synthesis of 1-(pyridine-3-carbonyl)pyrrolidin-2-one ( 1a ) and 1-(2-propyl-1-pentanoyl)pyrrolidin-2-one ( 1b ) by cyclization of the corresponding GABA derivatives, is reported. Two different methods are developed. For the synthesis of 1a , the parent molecule 4-[(pyridine-3-carbonyl)-amino]butanoic acid ( 2a ) is treated first with thionyl chloride and then with triethylamine. The second derivative, 1b , is produced by an intramolecular dehydration of 4-(2-propylpentanoylamino)butanoic acid ( 2b ) using an acid catalyst.     

Asymmetric radical additions using chiral 1,3-dioxolane-4-ones

Moderate facial selectivities are observed in additions of alkyl radicals to the chiral (c,d) olefin (2S)-2-tert-butyl-5-ethoxycarbonylmethylene-1,3-dioxolane-4-one 1. The following hydrogen abstraction from tributylstannane proceeds with excellent asymmetric stereocontrol, leading to two of four possible diastereoisomers with high diastereomeric excesses. Additions of chiral radicals obtained from (2R,5R)-5-alkyl-5-bromo-1,3-dioxolane-4-ones to ethyl acrylate show high asymmetric 1,3-induction.     

Synthesis,Bioactivity and Crystal Structure Analysis of 2-（Benzo [d]isothiazol-3-yloxy）-N-（3-cyano-l-（4- fluorophenyl）-lH-pyrazol-5-yl） Acetamide

A novel benzisothiazolin-3-one derivative, 2-（benzo[d]isothiazol-3-yloxy）-N-（3- cyano-l-（4-fluorophenyl）-lH-pyrazol-5-yl） acetamide （8）, was synthesized from the initial compound benzo[d]isothiazol-3（2H）-one （BIT） 1 and 4-fluoroaniline 3. The structure of the target compound 8 was determined by elemental analyses, IR and 1H NMR. The single crystals of intermediate compound 6 and the target compound 8 were obtained and determined by X-ray diffraction analysis. The preliminary biological activity was also evaluated and the results showed tile target compound exhibited a good anti-microbial activity.     

Mannich Base Derivatives of 1,2-Benzisothiazolin-3-one: Syntheses,Crystal Structures and Bioactivities

Twelve Mannich base derivatives of 1,2-benzisothiazolin-3-one were synthesized by the reaction of 1,2-benzisothiazol-3(2H)-one(BIT) with different amines and formaldehyde. All the compounds were characterized by elemental analysis, IR spectroscopy, MS and 1H NMR. The crystal structure for 2,2'-methylenebis(benzo[d]isothiazol-3(2H)-one)(3) has been determined by X-ray single-crystal structure analysis. Compound 3(C15H10N2O2S2) crystallizes in the monoclinic system, space group C2/c with a = 25.052(8), b = 4.510(1), c = 11.948(4) , β = 100.992(4)o, V = 1325.2(7) 3, Mr = 314.37, Dc = 1.576 Mg·m-3, μ = 0.25 mm-1, F(000) = 648, Z = 4, R = 0.034 and wR = 0.087. The preliminary biological test indicated that the compounds(2b, 2c) showed growth inhibitory activity against the gram-positive and gram-negative bacteria.     

Theoretical Investigations into the Intermolecular Hydrogen-bonding Interactions between Azacyclopentane-2-one and N-Methylol Ethanone

The structures of the complexes formed between N-methylol ethanone(model molecule of ceramide) and azacyclopentane-2-one(the model molecule of azone) have been fully optimized at the B3LYP/6-311++G** level.The intermolecular hydrogen bonding interaction energies have been calculated by using the B3LYP/6-311++G**,B3LYP/6-311++G(2df,2p),MP2(full)/6-311++G** and MP2(full)/6-311++G(2df,2p) methods,respectively.The results show that strong O–H···O=C,N–H···O=C and C–H···O=C hydrogen bonds could exist between azacyclopentane-2-one and N-methylol ethanone.The formation of the complexes might change the conformation of ceramide molecule and thus cause better percutaneous permeation for the drugs.This is perhaps the origin of the permeation enhances the activity of azone for medicament,as is in accordance with the experimental results.The hydrogen-bonding interactions follow the order of(a) (c) (b) (d) (g) ≈(e) ≈(i) (h) (f).The analyses of frequency,NBO,AIM and electron density shift are used to further reveal the nature of the complex formation.In the range of 263.0~328.0 K,the complex is formed via an exothermic reaction,and the solvent with lower temperature and dielectric constant is favorable to this process.     

Synthesis and Biological Activity of New 2-{[6-Methyl-2-(pyrrolidin-1-yl)pyrimidin-4-yl]oxy}acetohydrazide Derivatives

Russian Journal of General Chemistry - The reaction of 6-methyl-2-(pyrrolidin-1-yl)pyrimidin-4(3H)-one with methyl chloroacetate, followed by hydrazinolysis, gave...     

Synthesis,Crystal Structure and Properties of Ethyl 3,9-Dimethyl-7-phenyl- 6H-dibenzo[b,d]pyran-6-one-8-carboxylate

Ethyl 3,9-dimethyl-7-phenyl-6H-dibenzo[b,d]pyran-6-one-8-carboxylate(C24H20O4, Mr = 372.40) has been synthesized and its structure was determined by 1H and 13C NMR, ESI-MS, elemental analysis, and X-ray single-crystal diffraction. The crystal belongs to the monoclinic system, space group P21/n, with a = 8.3674(11), b = 10.6683(14), c = 11.3817(15) , α = 95.596(2), β = 109.866(2), γ = 94.495(2)°, V = 944.2(2)3, Z = 2, Dc = 1.310 g/cm3, μ = 0.089 mm-1, F(000) = 392, R = 0.0482 and wR = 0.1281 for 2916 observed reflections with I 2σ(I). In the crystal structure, the fused tricyclic nucleus of the title compound is not fully coplanar. Analysis of the crystal packing indicates aromatic π-π stacking interactions occurring between the fused tricyclic aromatic rings of neighboring molecules in which a maximum overlap of the π-electron systems was achieved. Fluorescence and thermal studies indicate that compound 3 has good optical properties and thermal stability.     

SYNTHESIS,CRYSTAL STRUCTURE,AND DFT STUDY OF 1-(PYRROLIDIN-1- YL-METHYL)-4-(THIOPHEN-2-YL-METHYL)- [1,2,4]TRIAZOLO[4,3-a]QUINAZOLIN-5(4H)-ONE

Journal of Structural Chemistry - In this paper, the triazoloquinazolinone derivative 1-(pyrrolidin-1-yl-methyl)-4-(thiophen-2-yl-methyl)[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one is synthesized...     

Synthesis and aminomethylation of some heterocyclic α-nitroxyalkyl NH acids

The recently discovered synthetic route to quaternary ammonium salts of a new series via N-aminometylation of 4,4-bis(nitroxymethyl)oxazolidin-2-one was extended to other NH acids obtained for the first time by O-nitration of known a-hydroxyalkyl derivatives of 4-methyloxazolidin-2-one, pyrrolidin-2-one, and benzimidazole. In the aminomethylation of these NH acids, dimethylamine and morpholine were used as the amine components.     

Synthetic [FeFe]-H2ase models bearing phosphino thioether chelating ligands

Through the oxidation-reduction combination procedure, the neutral tri-substituted {2Fe3S} complex 2 was synthesized by replacing the CO ligand in 1 with phosphine. This substitution leads to the Fe-Fe bonds in 1 and 2 with large Lewis basicity difference, i.e. △pK_a^MeCN~10.