Synthesis of (S)-γ-Lactones with a Combination of Lipase-Catalyzed Resolution and Mitsunobu Reaction

Six kinds of (S)-γ-lactones [e.g., (S)-γ-decalactone, (S)-γ-undecalactone, and (S)-γ-jasmolactone] were synthesized with 71–88% yields and >97% optical purities by combining lipase-catalyzed resolution with the Mitsunobu reaction.     

Stereoselective Synthesis of (1Z,3E)-2-Ethoxycarbonyl-Substituted 1,3-Dienes via Stille Coupling of (E)-α-Stannyl-α,β-Unsaturated Esters with Alkenyl Halides

Palladium-catalyzed hydrostannylation of alkynyl esters in benzene at room temperature gives stereoselectively (E)-α-stannyl-α,β-unsaturated esters 1 in good yields. (E)-α-Stannyl-α,β-unsaturated esters 1 are difunctional group reagents that undergo Stille coupling reactions with alkenyl halides 2 in the presence of Pd(PPh₃)₄ and CuI co-catalyst to afford stereoselectively (1Z,3E)-2-ethoxycarbonyl-substituted 1,3-dienes 3 in good yields.     

Study of Aqueous Biomolecules with Magnetic Flux Using Density,Viscosity, and Surface Tension Probe at 304.15 K

Doses of 0.0150 weber m^?2 magnetic flux for 30 minutes are given to four series of biomolecules in aqueous medium, densities (ρ), viscosities (η), and surface tension (γ) were measured at 304.15 K. The vitamins and carbohydrates decrease densities and viscosities and the difference of density from magnet to aqueous solution in order of dextrose (? 0.00025 kg m^?3) > fructose (? 0.00021 kg m^?3) = B6 (? 0.00021 kg m^?3) > starch (? 0.00018 kg m^?3) > B1 (? 0.0018 kg m^?3), while viscosity in order of starch (? 0.0044 kg m^?1s^?1) > fructose (? 0.0037 kg m^?1s^?1) > B1(? 0.0018 kg m^?1s^?1) > dextrose (? 0.0016 kg m^?1s^?1) > B6 (? 0.0012 kg m^?1s^?1). The surface tension also decreases in vitamin and carbohydrate. The proteins show increase in ρ, η, and γ value hence casein decrease the density and viscosity. The glutamine show increase in density and surface tension while decrease in viscosity and vice versa to alanine. These orders of the data indicate the intermolecular force between water and bimolecules in magnetic flux.     

SmI3-Catalyzed Addition of Amines to α,β-Unsaturated N-Acylbenzotriazoles

The addition of amines to α,β-unsaturated N-acylbenzotriazoles could be catalyzed by samarium triiodide (SmI₃) at ambient temperature. α,β-Unsaturated aliphatic N-acylbenzotriazoles afforded bis-addition products (β-amino amides), whereas N-cinnamoylbenzotriazoles gave acylated products (cinnamoylamides) exclusively.     

Interactions of γ-Cyclodextrin with the Mixed Micelles of Anionic Surfactants and Their Inclusion Complexes Formation

Interactions of γ-cyclodextrin (γ-CD) with the single and mixed micelles of sodium dodecyl sulfate (SDS) and sodium lauroyl sarcosine (SLAS) have been studied at different concentrations of γ-CD by using conductivity measurements. From conductivity data, the pure and mixed critical micellar concentration (cmc), the equivalent ionic conductivities of the monomeric species (Λ _m), the associated species (Λ _assc) and the micelle (Λ _mic), the degree of counterion dissociation (χ) in the presence of γ-CD have been evaluated from the slope of the conductivity versus concentration plots for the pure and binary mixture of surfactants. From the dependence of cmc of the surfactantson γ-CD concentration, we have deduced the association constant (K) of surfactant-γ-CD inclusion complexes assuming 2:1 stoichiometry. Theories of Clint, regular solution, and Motomura's have been used for the evaluation of ideality or nonideality of the mixed system. Mixed micelles were found to be rich in SDS content in the presence and the absence of γ-CD. The cmc values have been used to evaluate the transfer of standard free energy of micelles (ΔG⁰ _M,tr) from the aqueous medium to additive medium.     

The Reaction of Electron-Deficient Cyclopropane Derivatives with Aromatic Amines

Abstract

N-Aryl-trans,trans-α-carboxyl-β-benzoyl-γ-aryl-γ-butyrolactams were synthesized in high yields with high stereoselectivity by the reaction of electron-deficient cyclopropane derivatives, cis-1-benzoyl-2-aryl-6,6-dimethyl-5,7-dioxo-spiro-[2 (a) Zhang , J. ; Blazecka , P. G. ; Davidson , J. G. First direct reductive amination of mucochloric acid: A simple and efficient method for preparing highly functionalized α,β-unsaturated γ-butyrolactams . Org. Lett. 2003 , 5 , 553 – 556 ; (b) Sarma, K. D.; Zhang, J.; Curran, T. T. Novel synthons from mucochloric acid: The first use of α,β-dichloro-γ-butenolides and γ-butyrolactams for direct vinylogous aldol addition. J. Org. Chem. 2007, 72, 3311–3318 . [Google Scholar] 5 (a) Chen , Y. L. ; Ding , W. Y. A simple approach to highly stereoselective synthesis of β γ-trans-γ-butyrolactones . Chem. J. Chin. Univ. 1998 , 19 , 1614 – 1616 ; (b) Chen, Y. L.; Ding, W. Y.; Cao, W. G.; Lu, C. Stereoselective synthesis of N-aryl-trans,trans-α-carboxyl-β-methoxycarbonyl-γ-aryl-γ-butyrolactones. Synth. Commun. 2002, 32, 1953–1960.  [Google Scholar]]-4,8-octadiones, with aromatic amines. The reaction mechanism was proposed.     

One-Pot,Fluoride-Promoted Wittig Reaction

A one-pot, fluoride-promoted Wittig reaction was developed. The reactions of ethyl α-bromoacetate with aliphatic, aromatic, and heteroaromatic aldehydes in the presence of tri-n-butylphosphine and tetrabutylammonium fluoride produced α,β-unsaturated esters in good to excellent yields and E-stereoselectivity. Under the same conditions, reactions of ethyl α-bromopropionate, α-bromo acetonitrile, and α-bromoacetophenone with aliphatic and aromatic aldehydes in the presence of tri-n-butylphosphine and tetrabutylammonium fluoride produced the expected α,β-unsaturated derivatives in good E-stereoselectivity. The protocol was extended to semistabilized ylides and applied to the synthesis of some combretastatin analogs.     

N-Aryl Modification in γ-Lactam: Design and Synthesis of Novel Monocyclic γ-Lactam Derivatives as Inhibitor for Bacterial Propagation

In search of novel γ-lactam antibacterial agents as non-β-lactam mimics of some γ-lactam antibiotics, N-aryl modification in the γ-lactam ring has been made to synthesize compounds 4–8 in two to six steps. Compound 4 was synthesized using the intermolecular Michael addition of diethyl N-(6-coumarinyl)-2-aminomalonate and 3-aryl/(2-heteroaryl)acryloyl chloride followed by intramolecular amidification. Hydrolysis and stereoselective decarboxylation of 4 resulted in the formation of trans- γ-lactam carboxylic acids (5), which on side chain homologation followed by saponification of the intermediate γ-lactam monoester (7) afforded γ-lactam carboxylic derivatives 8. Moderate to good bacterial growth inhibition was observed for some of the synthesized compounds against E. coli and S. aureus.     

Kinetic energy density in terms of electron density for closed-shell atoms in a bare Coulomb field

A long-term aim in density functional theory is to obtain the kinetic energy density t(r) in terms of the ground-state electron density ρ(r). Here, t(r) is written explicitly in terms of ρ(r) for an arbitrary number 𝒩 of closed shells in a bare Coulomb field. In the limit as 𝒩→∞, closed results for t(r) follow from the earlier analysis of ρ(r) by Heilmann and Lieb. [Phys. Rev. A 52 , 3628 (1995)]. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66 : 281–283, 1998     

Selective Bromination of Dehydroacetic Acid with N-Bromosuccinimide

Bromination of dehydroacetic acid has been carried out with N-bromosuccinimide under various conditions. The reactions led to selective bromination, thereby offering efficient synthesis of 3β-bromodehydroacetic acid (3), 3β,5-dibromodehydroacetic acid (4), 3β,3β-dibromodehydroacetic acid (5), and 3β,3β,5-tribromodehydroacetic acid (6).     

Synthesis of new α-hydroxyphosphonates and α-acetoxyphosphonates

A series of new α-hydroxyphosphonate (5–14) have been synthesized in high yields by reaction of β-chloro-α,β-unsaturated aldehydes (1–4) and trialkyl phosphite in the presence of chlorotrimethylsilane at room temperature under solvent-free conditions. In addition, compounds (5–14) were reacted with acetic anhydride in DBU to give the new α-acetoxyphosphonate derivatives (15–23). All these phosphonates (5–23) were obtained as mixtures of two (E and Z) isomers and fully characterized by multinuclear (¹H, ¹³C, and ³¹P) NMR, IR spectroscopy and HRMS.     

Synthesis,X-ray crystallographic studies,DFT calculations and nanostructural features of annulated imidazo[4,5-b]pyridine derivatives

Friedländer-type condensation of 5-amino-4-cyano-1-(phenyl/p-substitutedphenyl)imidazole with cycloalkanone was done by refluxing the mixture with a suspension of anhydrous aluminum chloride in dry 1,2-dichloroethane to produce 7-amino-3-aryl(5,6)cycloalkanoimidazolo[4,5-b]pyridine. Single X-ray crystallographic diffraction studies had shown that compounds had different types of heterodimeric, homodimeric π–π stacking, T-type stacking, and intermolecular hydrogen bonds which lead to nanostructure formation detected by scanning electron microscope. DFT calculation had also been performed to quantify heterodimeric π–π and T-stacking interactions.     

Nmp-based ionic liquids: Recyclable catalysts for both hetero-Michael addition and Knoevenagel condensation in water

A series of novel N-methyl piperidine (Nmp)-based ionic liquids with 1,2-propanediol group are synthesized and used as catalysts for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation at room temperature in water; and all the examined substrates could be transformed into corresponding products in good to excellent yields. Meanwhile IL-catalyzed hetero-Michael addition of α,β-unsaturated amides in water has not been reported in the previous literatures. Additionally, the catalyst is recyclable for the two reactions. This finding provides a green catalyst for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation in water.     

Efficient Synthesis of 3-R-Boc-amino-4-(2,4,5-trifluorophenyl)butyric Acid

3-R-Boc-amino-4-(2,4,5-trifluorophenyl)butyric acid (9) was obtained from L-methionine in six steps with a total yield of 32%. The α-amino acid segment of L-methionine was transferred to chiral aziridine by amino protection, reduction, hydroxyl derivation, and cyclization. After ring opening of 2,4,5-trifluoro-phenyl magnesium bromide, the methylthiomethyl group was then hydrolyzed to β-amino alcohol and oxidized to the target β-amino acid.     

Studies of 2-Substituted 1,3-Oxazolidin-5-ones and 1,3-Oxazinan-6-ones as Precursors for the Synthesis of N-Alkyl-β-Amino Acids

1,3-Oxazolidin-5-ones and 1,3-oxazinan-6-ones have been shown to be useful precursors for the synthesis of N-methyl α- and β-amino acids, respectively. The methodology has now been expanded to allow for the synthesis of N-alkyl-β-amino acids.     

Enantio- and Diastereoselective Oxidation of N-Alkylimines Using Chiral α-Bromonitriles and Hydrogen Peroxide System

Chiral α-bromonitriles were prepared with good chemical and optical yields starting from natural α-amino acids by dehydrating the corresponding α-bromoamides with thionyl chloride. The combined system α-bromonitriles/hydrogen peroxide was examined for the enantio- and diastereoselective oxidation of N-alkylimines in basic media at room temperature. The oxidation of N-tertiobutylarylimines leads to optically active oxaziridines with moderate enantiomeric excess. However, the oxidation of (S)-1-phenylethylarylimines affords the corresponding oxaziridines with good diasteromeric excess up to 97/3 as proved by gaseous-phase chromatography.