Asymmetric Synthesis of （-）-（4R, 5R）-4-[5-（Benzo[1, 3]dioxol-5-yl）-4- hydroxyl- 1-（pyridin-2-yl）-4, 5-dihydro- 1H-pyrazol-3-yl]benzamide

For discovering novel small molecule inhibitors of transforming growth factor-β1(TGF-β1)type-I receptor(ALK5),we designed1,3,5-triaryl-4-hydroxyl-4,5-dihydro-1H-pyrazole(1)as target compound,mimic the structure of SB-431542which is a2-pyridyl substituted triarylimiazole inhibitor of ALK51.Racemic compound1showed moderate ALK5inhibitory activity in luciferase reporter assays[inhibition(%control):0.1umol/L8.79%;1umol/L19.05%].To investigate the influence of the absolute configuration of…     

Origin of chiral induction in radical reactions with the diastereoisomers (5R)- and (5S)-5-l-menthyloxyfuran-2[5H]-one

Acetalization of 5-hydroxyfuran-2[5H]-one with l-menthol yields (5R)- (1) and (5S)-5-l-menthyloxyfuran-2[5H]-one (2) in equal amounts. The diastereomer 1 crystallizes preferentially. For the first time, the isolation of pure diastereoisomer 2 is reported. Different diastereoselectivities were observed in the radical tandem reaction of 1 and 2 with N,N-dimethylaniline. The privileged conformations in solution of the substrates and the products of the radical reaction were then determined, and X-ray crystal structure analyses were carried out on the reaction products. The different stereoselectivities in both cases are explained by different orientations of the menthyloxy substituent.     

A synthetic entry to isoxazolo[5,4-d]pyrimidine-4(5H)thione and isothiazolo[4,3-d]isoxazole

4-Thiocarbamoyl-5-aminoisoxazole 4 was used as a convenient starting material for preparing both isoxazolo[5,4-d]pyrimidine-4(5H)thiones 5 and 4-aminoisothiazolo[4,3-d]isoxazole 6 . The structure of the latter compound was definitively assigned by X-ray analysis.     

Synthesis of (1R,4E,5S)-4-{[(E)-(azinyl)diazenyl]methylidene}-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones and (1R,4R,5R)-4-([1,2,4]triazolo[4,3-x]azin-3-yl)-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones

4-[(Heteroaryldiazenyl)methylidene] and 4-([1,2,4]triazolo[4,3-x]azin-3-yl) substituted (1R,5R)-4-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones 6/6′ and 7/7′ were obtained in a one-pot transformation of the enamino lactone 2 with hydrazinoazines 3a–g followed by oxidation of the intermediate mixture of isomeric enehydrazines 4/4′ and hydrazones 5/5′ with lead tetraacetate. The oxidation selectivity was dependent on the ratio of isomeric intermediates 4/4′ and 5/5′. Treatment of 7b with lead tetraacetate led to α-acetoxylated compound 11, while bromination of 9b afforded a 1:1 mixture of α-bromination products 12 and 12′, which were separated by medium pressure liquid chromatography (MPLC). The structures of intermediates and products were confirmed by NMR and X-ray diffraction.     

Concerted rearrangement versus heterolytic cleavage in anionic [2,3]- and [3,3]-sigmatropic shifts. A DFT study of relationships among anion stabilities,mechanisms, and rates

The anionic [2,3] sigmatropic Wittig rearrangements of deprotonated 4-hetera-1-pentenes and the anionic [3,3] sigmatropic Cope rearrangements of 3-substituted-1,5-hexadienes were explored by using density functional theory calculations. While the deprotonated anionic 3-hydroxy-1,5 hexadiene (2a), 3-thiohydroxy-1,5-hexadiene (2c), and 3-formamidyl-1,5-hexadiene (2d) Cope substrates undergo concerted rearrangements, the deprotonated anionic 3-amino-1,5-hexadiene (2b) and 3-methyl-1,5-hexadiene (2e) Cope substrates follow nonconcerted cleavage/recombination pathways. We have also found that the gas-phase Wittig (1a), aza-Wittig (1b), and carba-Wittig (1c) reactions proceed via nonconcerted cleavage/recombination pathways. These results are compared with previous results on the Cope rearrangements of deprotonated anionic 3-hydroxy-1,5-hexadiene and 3-amino-1,5-hexadiene anions. A previously established model that heterolytic and homolytic bond dissociation energies can be used to predict how anionic amino- and oxy-Cope substrates will react is generalized to account for the reactivity of other Cope substrates as well as for the Wittig rearrangements. There is also a relationship between the basicity of the anionic substituent in the Cope rearrangement and the reaction pathway: the more basic the substituent anion, the less stable it is, and the more likely it is that cleavage will occur. A first step toward studying these reactions in solution was also taken by calculating energetics for some of the rearrangements with a lithium counterion present.     

3-[N-(4-甲基苯基)氨基羰基]-5-[4-(4-甲酸基苯甲氧基)苯亚甲基]-2,4-噻唑烷二酮的合成

以对甲苯胺和对甲基苯甲酸甲酯为起始原料,经NBS溴化、亲核取代、酸水解和Knoevenagel缩合等6步反应合成了抗细菌生物膜化合物—3-[N-(4-甲基苯基)氨基羰基]-5-[4-(4-甲酸基苯甲氧基)苯亚甲基]-2,4-噻唑烷二酮,总收率57.3％,其结构经1H NMR,ESI-MS和元素分析确证.     

Asymmetric salt effects on anion/cation reactions: A comparative study of the [Fe(CN)6]4− + [Co(NH3)5pz]3+ and [Ru(NH3)5pz]2+ + [Co(C2O4)3]3− reactions

The kinetics of electron transfer reactions between [Fe(CN)₆]^4? and [Co(NH₃)₅pz]³⁺ and between [Ru(NH₃)₅pz]²⁺ and [Co(C₂O₄)₃]^3? was studied in concentrated salt solutions (Na₂SO₄, LiNO₃, and Ca(NO₃)₂). An analysis of the experimental kinetic data, k_obs, permits us to obtain the true (unimolecular) electron transfer rate constants corresponding to the true electron transfer process (precursor complex → successor complex), k_et. The variations of both, k_obs and k_et, with salt concentrations are opposite for these reactions. These opposite tendencies can be rationalized by using the Marcus–Hush treatment for electron transfer reactions. The conclusion is that the negative salt effect found for the first reaction ([Fe(CN)₆]^4? + [Co(NH₃)₅pz]³⁺) is due to the increase of the reaction and reorganization free energies when the concentration of salt increases. In the case of the second reaction ([Ru(NH₃)₅pz]²⁺ + [Co(C₂O₄)₃]^3?), the positive salt effect observed is caused by the fact that the driving force becomes more favorable when the concentration of salt increases. Thus, it is shown that for anion/cation electron transfer reactions the kinetic salt effect depends on the charge sign of the oxidant (and the reductant). © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 37: 81–89, 2005     

Syntheses of (R) [4-2H2] 2-Amino-3-Butenoic Acid (Vinylglycine) and (R) [4-2H2, 5-2H3] Methionine

Treatment of (R) methionine sulfoxide with NaOD led to exchange of the C-4 methylene and C-5 methyl protons; exchange of the chiral C-2 proton did not occur. Reducation with mercaptoacetic acid gave (R)-[4-²H₂, 5-²H₃] methionine. The latter was converted into its carbobenzyloxy methyl ester sulfoxide, pyrolysis of which followed by deprotection yielded (R)-[4-²H₂] vinylglcine as the hydrochloride.     

Synthesis of (−)-(4R,5R)- and (+)-(4S,5S)-1-alkyl-4-(4′-nitrophenyl)-1-azonium-3,7-dioxabicyclo[3.3.0]octane halides

A preparative method has been proposed for the synthesis of bicyclic quaternary ammonium salts via sequential treatment of (–)-(1R,2R)- and (+)-(1S,2S)-1-(4-nitrophenyl)-2-amino-1,3-propanediol with paraform followed by an alkyl halide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1394–1395, October, 1990.     

Synthesis,spectral, DFT calculations and antibacterial studies of Fe(III) complexes of new fluorescent Schiff bases derived from imidazo[4',5':3,4]benzo[1,2‐c]isoxazole

New fluorescent heterocyclic ligands were synthesized by the reaction of 8‐(4‐chlorophenyl)‐3‐alkyl‐3H‐imidazo[4',5':3,4]benzo [1,2‐c]isoxazol‐5‐amine with p‐hydroxybenzaldehyde and p‐chlorobenzaldehyde in good yields. The coordination ability of the ligands with Fe³⁺ ion was examined in an aqueous metanolic solution. Schiff base ligands and their metal complexes were characterized by elemental analyses, IR, UV–vis, mass, and NMR spectra. The optical properties of the compounds were investigated and the results showed that the fluorescence of all compounds is intense and their obtained emission quantum yields are around 0.15 – 0.53. Optimized geometries and assignment of the IR bands and NMR chemical shifts of the new complexes were also computed by using density functional theory (DFT) methods. The DFT‐calculated vibrational wavenumbers and NMR chemical shifts are in good agreement with the experimental values, confirming suitability of the optimized geometries for Fe(III) complexes. Also, the 3D‐distribution map for HOMO and LUMO of the compounds were obtained. The new compounds showed potent antibacterial activity and their antibacterial activity (MIC) against Gram‐positive and Gram‐negative bacterial species were also determined. Results of antibacterial test revealed that coordination of ligands to Fe(III) leads to improvement in the antibacterial activity.     

A DFT study of the [4+2] cycloadditions of conjugated ketenes (vinylketene, imidoylketene and formylketene) with formaldimine. The pericyclic or pseudopericyclic character from magnetic properties

A comprehensive B3LYP/6-31+G^∗ study of the nature of the [4+2] cycloadditions of conjugated ketenes, vinylketene, imidoylketene and formylketene, with formaldimine was conducted. For each reaction, the complete pathway was determined and changes in different magnetic properties (magnetic susceptibility, χ, magnetic susceptibility anisotropy, χ_anis, and the nucleus-independent chemical shift, NICS) were monitored along the reaction profile with a view to estimate the aromatization associated to the process. We have also applied the ACID (anisotropy of the current-induced density) method with the same purpose. The deep analysis of the results indicates the existence of both disrotatory and conrotatory pericyclic paths for the cyclization step of the cycloaddition of vinylketene with formaldimine and the pseudopericyclic character of reactions with imidoylketene and formylketene.     

Synthesis of 3-cyano-4,6-dinitrobenzo[d]isoxazole and its reactions with anionic nucleophiles

The action of various anionic O-, N-, and S-nucleophiles on 3-cyano-4,6-dinitro-benzo[d]isoxazole mostly resulted in regiospecific nucleophilic substitution for the nitro group in position 4. With an excess of an nucleophilic reagent, the nitro group in position 6 was also replaced. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 523–528, March, 2006.     

Theoretical study on structures and aromaticities of P5(-) anion, [Ti (eta(5)-P5)]- and sandwich complex [Ti(eta(5)-P5)2]2-

The equilibrium geometries, energies, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICSs) of the ground state of P5(-) (D(5h)) anion, the [Ti (eta(5)-P5)]- fragment (C(5v)), and the sandwich complex [Ti(eta(5)-P5)2]2- (D(5h) and D(5d)) are calculated by the three-parameter fit of the exchange-correlation potential suggested by Becke in conjunction with the LYP exchange potential (B3LYP) with basis sets 6-311+G(2d) (for P) and 6-311+G(2df) (for Ti). In each of the three molecules, the P-P and Ti-P bond distances are perfectly equal: five P atoms in block P5(-) lie in the same plane; the P-P bond distance increases and the Ti-P bond distance decreases with the order P5(-), [Ti(eta(5)-P5)2]2-, and [Ti (eta(5)-P5)]-. The binding energy analysis, which is carried out according to the energy change of hypothetic reactions of the three species, predicts that the three species are all very stable, and [Ti (eta(5)-P5)]- (C(5v)), more stable than P5(-) and [Ti(eta(5)-P5)2]2- synthesized in the experiment, could be synthesized. NICS values, computed for the anion and moiety of the three species with GIAO-B3LYP, reveal that the three species all have a larger aromaticity, and NICS (0) of moiety, NICS (1) of moiety, and minimum NICS of the inner side of ring P5 plane in magnitude increase with the order P5(-), [Ti(eta(5)-P5)2]2-, and [Ti (eta(5)-P5)]-. By analysis of the binding energetic and the molecular orbital (MO) and qualitative MO correlation diagram, and the dissection of total NICS, dissected as NICS contributions of various bonds, it is the main reason for P5(-) (D(5h)) having the larger aromaticity that the P-P sigma bonds, and pi bonds have the larger diatropic ring currents in which NICS contribution are negative, especially the P-P sigma bond. However, in [Ti (eta(5)-P5)]- (C(5v)) and [Ti(eta(5)-P5)2]2- (D(5h), and D(5d)), the reason is the larger and more negative diatropic ring currents in which the NICS contributions of P-P pi bonds and P5-Ti bonds including pi, delta, and sigma bonds, especially P5-Ti bonds, are much more negative and canceled the NICS contributions of P and Ti core and lone pair electrons.     

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...     

(6R,7R)-7-氨基-3-[2-(4-甲基-5-噻唑)乙烯基]-8-氧代-5-硫-1-氮杂双环[4.2.0]辛-2-烯-2-羧酸的合成

以1-磺丁基-3-甲基咪唑硫酸氢盐离子液体(b)为反应介质,7-氨基头孢烷酸(7-ACA,2)为原料,与4-甲基-5-甲酰基噻唑经缩合反应制得(6R,7R)-7-氨基-3-[2-(4-甲基-5-噻唑)乙烯基]-8-氧代-5-硫-1-氮杂双环[4.2.0]辛-2-烯-2-羧酸(7-ATCA,1),其结构经1H NMR,13C NMR和IR表征。考察了离子液体及其用量,原料摩尔比r[n(4-甲基-5-甲酰基噻唑)∶n(2)],反应温度和反应时间对1收率的影响。在最佳反应条件[b为反应介质,b用量为20 m L,r=1.3,于65℃反应5 h]下,1收率可达90%以上。     

Reaction of 4-[2-(arylmethylidene)hydrazinylidene]cyclohexa-2,5-dienones with aromatic amines

4-[2-(Arylmethylidene)hydrazinylidene]cyclohexa-2,5-dienones react with aromatic amines according to the 1,8-addition pattern with formation of N-aryl-N′-(4-oxocyclohexa-2,5-dien-1-ylidene)arenecarbohydrazonamides. The reaction is favored by increase of electron-donating power of the substituent in aromatic amine and electron-withdrawing power of the benzylidene fragment of quinone imine. A probable reaction scheme has been proposed.