Cholesterol Binding to Simple Micelles in Aqueous Bile-Salt–Cholesterol Solutions

The true thermodynamic activity (A_T) of cholesterol (Ch) in aqueous solutions containing taurocholate (TC)–Ch was determined by employing a direct assay of a 1 × 2-cm silicone polymer film with 0.025 cm thickness. Using theA_Tdata, information on the nature of micellar species present in the TC–Ch system, and employing a binding-site model previously developed for tauroursodeoxycholate (TUDC)–Ch and taurochenodeoxycholate (TCDC)–Ch systems, it appeared that the Ch-binding affinity for simple bile-salt micelles corresponds precisely with the order of hydrophobicity, TUDC < TC < TCDC. Further, although simple TC micelles and simple TCDC micelles have similar binding capacities, the first Ch binding to a simple TC micelle may not significantly facilitate the second Ch binding, as occurs in simple TCDC micelles. For TUDC–Ch, TC–Ch, and TCDC–Ch systems, the concentration of bound simple micelles increased with increasingA_Tvalues, whereas the unbound simple micelle concentration decreased proportionally. These results provide insights into the possible influence of bile-salt species on Ch-binding to simple micelles in bile-salt–Ch solutions.     

Asymmetric anti‐Selective Michael Reaction of Imidazole‐Modified Ketones with trans‐β‐Nitroalkenes

The successful application of imidazole‐modified ketones in asymmetric anti‐selective Michael reactions with trans‐β‐nitroalkenes is presented by employing a newly developed 3‐bromothiophene‐modified chiral diamine ligand. The corresponding conjugate adduct was submitted to further transformations with Grignard reagents to solve the problem of α‐site selectivity of simple linear ketones. Additionally, the syn‐selective product was obtained by treating the anti‐selective adduct with a simple base. In this way, the site‐specific products for both diastereomers in the asymmetric conjugate addition of simple ketones to nitroalkenes can be obtained.     

Domino synthesis of pyrimido and imidazoquinazolinones

A simple method for the synthesis of N-alkyl-2-arylquinazolin-4-amines, methyl 4-((2-arylquinazolin-4-yl)amino) butanoates, 6-aryl-2,3-dihydro-4H-pyrimido[1,2-c]quinazolin-4-ones, and 5-arylimidazo[1,2-c]quinazolin-3(2H)-ones has been described. It involves a simple reaction of N-(2-cyanophenyl)-substitutedbenzimidoyl chlorides with alkylamine, γ-aminobutyric acid, β-alanine, l -alanine, and glycine methyl esters hydrochloride in acetonitrile to afford the desired compounds after a series of instantaneous reactions that include Dimroth rearrangement. The reaction involves reflux for 12 hours, simple addition of reagents to an in situ generated benzimidoyl chloride, and simple workup, to form 21 examples of pure compounds in high yields. The active intermediate N-(2-cyanophenyl)-substitutedbenzimidoyl chlorides were formed by the reaction of N-(2-cyanophenyl)-substitutedbenzamides with thionyl chloride in a one-pot strategy. The alternative method described for this preparation deals with an exhausting multistep reactions starting from anthranilic acid.     

Copper‐Catalyzed Alkylarylation of Unactivated Alkenes: Synthesis of 3‐Alkyl Indolines from N‐Allyl Anilines and Alkanes

A rare example of C(sp³)?H functionalization of simple alkanes with unactivated alkenes is presented. In the presence of a copper salt and di‐tert‐butyl peroxide (DTBP), N‐allyl anilines underwent exo‐selective alkylation/cyclization cascade with unactivated alkenic bonds as radical acceptors and simple alkanes as radical precursors, providing a direct access to 3‐alkyl indolines. The present protocol features simple operation, broad substrate scope and great exo selectivity.     

Catalyst-free synthesis of novel 4H-indeno[1,2-b]furan-4-ones and furo[2,3-d]pyrimidines in water

An operationally simple, catalyst-free, and efficient protocol for the synthesis of novel 4H-indeno[1,2-b]furan-4-one and furo[2,3-d]pyrimidine derivatives by a one-pot reaction of 2-aminopyridines, 1,3-indandione, or barbituric acid and phenylglyoxal monohydrate in water at reflux, involving domino aldol condensation, Michael addition, and ring-closing reactions is described. This transformation has several advantages, including high yield, short reaction duration, simple workup, and simple purification.     

Synthesis of a New Library of Pyrano‐phenazine Derivatives via a Novel Three‐Component Protocol

The pyrano‐phenazine derivatives 6 were synthesized by an efficient procedure using the reaction between benzo[a]phenacin‐5‐ols with the condensation product of an aldehyde with Meldrum's acid in the presence of a catalytic amount of Et₃N at ambient temperature. The procedure is very simple, and products could be separated from the reaction media by simple filtration. High functional‐group tolerance both in the benzo[a]phenazin‐5‐ol and aldehyde moieties, facile reaction procedure, medium‐to‐high yields, and simple separation of the products from the reaction media are the advantages of this route.     

Complex formation of poly(4-vinyl-N-alkylpyridinium) salts or polymer containing flavin mononucleotide with indole derivatives

A charge-transfer-type complex formation between poly(4-vinyl-N-propylpyridinium bromide) (C3PVP), poly(4-vinyl-N-butylpyridinium bromide) (C4PVP) or poly(4-vinyl-N-benzylpyridinium chloride) (BzPVP), and indole derivatives or between polymer containing flavin mononucleotide residues and indole derivatives was studied in the presence of simple and polyelectrolytes. The association constant (K) of the complex formation with indole acetate increased in the order BzPVP > C4PVP > C3PVP, which indicated an important contribution by hydrophobic interaction. The addition of simple and polyelectrolytes decreased the association constants. This was explained by the “secondary salt effect” of the salts. The importance of the electrostatic interactions in the complexation systems was obvious. The influence of simple electrolytes on the K values was discussed theoretically according to Manning's theory.     

Classification and Representations of Low-Dimensional Nanomaterials: Terms and Symbols

A simple scheme, with special terms and symbols useful in categorizing various nanostructures, is introduced. Using “n-D in/on m-D” composite nanomaterials where n,m ≤ 2 as examples, we illustrate how these terms and symbols can be used to represent various hetero nanostructures. This simple nomenclature system also allows a systematization of a wide variety of multi-dimensional nanocomposite heterostructures.     

Formal [3 + 2] cycloaddition of azomethine ylides generated in situ with unactivated cyclic imines: A facile approach to tricyclic imidazolines derivatives

A simple and efficient method for the synthesis of tricyclic imidazolines derivatives via [3 + 2] 1,3-dipolar cycloaddition between nonstabilized azomethine ylide generated in situ with unactivated cyclic imines is reported here. The method provided easy and mild access to various fused tricyclic hexahydroimidazo[5,1-a]isoquinolines in excellent yields (up to 96%). This protocol is simple and easy to handle.     

A simple graphical method to pinpoint local pseudosymmetries in Z′ > 1 cases

An intuitive method is presented for detecting pseudosymmetries in Z′ > 1 cases as a complement to well‐proven strategies already available in the literature. It is based in the simple idea that the mid‐points between equivalent atoms in symmetrically related molecules are disposed according to simple well‐known patterns, which are easily recognizable by optical inspection. A number of Z′ = 4 cases in the literature are analyzed, which allows some of the potentialities of the method to be revealed.     

The use of load separation criterion and normalization method in ductile fracture characterization of thermoplastic polymers

Load separation is the theoretical basis for the single-specimen J-integral experiment and the incremental calculation of J-integral crack growth resistance (J-R) curves. This criterion has been experimentally studied in nongrowing crack records in several materials, and more recently a new method to extend the applicability to growing crack experiments has been proposed in testing steel. This article examines the applicability of the load separation criterion for evaluating ductile fracture mechanics parameters in rubber-modified polystyrenes and thermally treated polypropylene in the bending configuration. This criterion allows the load to be represented as the multiplication of two independent functions: a material deformation function and a crack geometry function. Its validity is evaluated with both stationary and growing crack experiments. η-factor calculation for smooth and side-grooved specimens was also tried using the simple method of Sharobeam and Landes, in order to identify material dependency. This article also investigates the applicability of the normalization method, based on the load separation criterion for evaluating J-R curves on PP and PS. A simple approach which combines a blunt notched and a precracked specimen experiment is proposed to determine the J-R curve of the materials studied. The resulting J-R curves are compared with multiple specimen results available in the literature for these materials. A good agreement between the J-R curves obtained from this simple method and from the multiple specimen technique was found. © 1996 John Wiley & Sons, Inc.     

Asymmetric Synthesis of Bicyclic Diol Derivatives through Metal and Enzyme Catalysis: Application to the Formal Synthesis of Sertraline

Enzyme‐ and ruthenium‐catalyzed dynamic kinetic asymmetric transformation (DYKAT) of bicyclic diols to their diacetates was highly enantio‐ and diastereoselective to give the corresponding diacetates in high yield with high enantioselectivity (99.9 % ee). The enantiomerically pure diols are accessible by simple hydrolysis (NaOH, MeOH), but an alternative enzyme‐catalyzed ester cleavage was also used to give the trans‐diol (R,R)‐ 1 b in extremely high diastereomeric purity (trans/cis=99.9:0.1, >99.9 % ee). It was demonstrated that the diols can be selectively oxidized to the ketoalcohols in a ruthenium‐catalyzed Oppenauer‐type reaction. A formal enantioselective synthesis of sertraline from a simple racemic cis/trans diol 1 b was demonstrated.     

Room‐Temperature ortho‐Alkoxylation and ‐Halogenation of N‐Tosylbenzamides by Using Palladium(II)‐Catalyzed CH Activation

The N‐tosylcarboxamide group can direct the room‐temperature palladium‐catalyzed C?H alkoxylation and halogenation of substituted arenes in a simple and mild procedure. The room‐temperature stoichiometric cyclopalladation of N‐tosylbenzamide was first studied, and the ability of the palladacycle to react with oxidants to form C?X and C?O bonds under mild conditions was demonstrated. The reaction conditions were then adapted to promote room‐temperature ortho‐alkoxylations and ortho‐halogenations of N‐tosylbenzamides using palladium as catalyst. The scope and limitation of both alkoxylations and halogenations was studied and the subsequent functional transformation of the N‐tosylcarboxamide group through nucleophilic additions was evaluated. This methodology offers a simple and mild route to diversely functionalized arenes.     

Fused-ring and linking group effects of proton donors and acceptors on simple H-bonded liquid crystals

Two fused-ring structures, 6-decyloxy-2-naphthoic acid C₁₀ONA (3) and 6-dodecyloxyisoquinoline IS (8), were synthesized and utilized as proton donor and acceptor moieties to construct a series of simple mesogenic supramolecules. The other complementary hydrogen-bonded (H-bonded) moieties are benzoic acids, thiophenecarboxylic acid and pyridines containing different alkyl chain lengths connected by ether and ester linkages, i.e. 4-alkoxybenzoic acid C _n OBA (1), terephthalic acid monoalkyl ester C _n COOBA (2), 2,5-thiophenedicarboxylic acid monodecyl ester C₁₀COOTHA (4), 4-alkoxypyridine C _n OP (6) and isonicotinic acid alkyl ester C _n COOP (7). Several series of simple mesogenic supramolecular dimers were constructed from 1:1 molar ratios of proton donors (C _n OBA, C _n COOBA, C₁₀ONA and C₁₀COOTHA) and proton acceptors (IS, C _n OP and C _n COOP), though the proton acceptor C _n COOP induced phase separation in all complexes. In order to investigate their fused-ring and linking group effects on the mesogenic properties of the H-bonded complexes, analogous simple supramolecular structures are compared. Supramolecular architecture and the distinct mesomorphism of these simple H-bonded liquid crystalline materials were confirmed by polarizing optical microscopy, DSC and powder X-ray diffraction experiments.     

A PRACTICAL ENZYMATIC METHOD FOR PREPARATION OF (S)-KETOPROFEN WITH A CRUDE CANDIDA RUGOSA LIPASE

A simple and practical method for the preparation of (S)-Ketoprofen (2-(3-benzoylphenyl) propionic acid) has been developed through the hydrolysis of its chloroethyl ester catalyzed by a cheap and commercially available crude Candida rugosa lipase preparation under an extremely acidic condition, pH 2.5, and in the presence of Tween-80. As the reaction was carried out in a shake flask with baffles, the degree of hydrolysis was enhanced from 31.5% to 42.2%. A needle-like crystalline of (S)-Ketoprofen was obtained with 95.7% e.e. after simple separation and purification.     

Thermal and photo-actuation in nematic elastomers

Mono domain nematic elastomers change shape by as much as 400% on being heated from the nematic to isotropic state. The reason is that nematic order, Q, elongates the distribution of chains and thus the network that they form. Experimental evidence for this, and simple theory is presented. A novel method to change Q, and hence obtain an analogous elastic strain, is to bend the nematic's rods by photoisomerization. On absorbing a photon, photochromes such as azo rods leave the (straight) trans state and adopt the cis (bent) form. We show data and give simple theory to explain this remarkable, reversible elastic phenomenon.     

The bonding in the ozone molecule: From a different perspective

A new qualitative treatment of the bonding in ozone is presented. It is based upon a combination of several simple concepts: the nonparticipation of the pairs of electrons tightly held in the atomic 2s orbitals; simple overlap of the 2p orbitals to form sigma bonds; interaction of three 2p orbitals to yield bonding and nonbonding pi molecular orbitals that are populated by electron pairs; and van der Waals repulsion between the two terminal oxygen atoms forcing these atoms apart to yield the bond angle of 117° as a compromise. Both the assumptions and the resulting bonding picture are in accord with the photoelectron spectroscopic data, the results from sophisticated molecular orbital calculations, and the common physical properties of ozone.     

Computer simulation of relaxation phenomena in star‐branched polymers. Temperature dependence

Dynamic Monte Carlo simulations of simple models of star‐branched polymers were conducted. A model star macromolecule consisted of f = 3 arms of equal length with a total number of polymer segments up to 800. The chain was confined to a simple cubic lattice with simple nearest neighbor attractive interactions. The relaxation phenomena were studied by means of autocorrelation functions in wide ranges of temperatures. Short‐time‐scale dynamic processes in the entire star‐branched chain were examined. It was found that under good solvent conditions the longest relaxation time of the end‐to‐center vector decreases with decreasing temperature. For low temperatures (below the Θ‐point) where the chain is collapsed, the dependence of the relaxation time on the temperature is opposite.     

Metal-free synthesis of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles via microwave-assisted synthesis pathway

Abstract

A simple, efficient, and metal-free methodology for the preparation of 2-mercaptobenzothiazole and derivatives in excellent yields via microwave-assisted pathway is reported. Our condition provides a convenient protocol for the synthesis of a diverse collection of 2-mercaptobenzothiazoles and 6-(4-substituted-1H-1,2,3-triazol-1-yl)-2-mercaptobenzothiazoles with a very simple purification process. This report provides an alternative protocol for fast access to the wide range of compounds for sequence synthesis and biological studies.