Condensed heterotricycles: Pyrido(1,2,3- de )(1,4)benzoxazines, pyrido(1,2,3- ef )(1,5)benzoxazepines and pyrido(1,2,3- fg )(1,6) benzoxazocines

Cyclization of N-(2-haloacyl)-8-hydroxy-l,2,3,4-tetrahydroqumolines4–7 and9 with alkali affords pyridobenzoxazinones21–24 and26 respectively and of the 4-chlorobutyramide13 with NaH, the benzoxazocinone31. Exposure of 3-chloropropionamide12 to NaH affords acrylamide15, benzoxazepinone28 or methyl benzoxazinone22 or mixtures thereof under various conditions.28 undergoes rapid base-catalysed ring contraction to22. NaH-catalysed ring closure of acrylamide15 affords mixtures of22 and28, while from the crotonamides16 and17, the methylbenzoxazepinones29 and30 are obtained preponderantly, the former amide yielding only traces of the ethyl benzoxazinone23.29 shows no propensity for ring contraction to give23. The cinnamoyl derivatives18,19 and20 are cyclized to benzyl benzoxazinones24,27 and25, respectively. The intermediacy of the phenyl benzoxazepinone39 in the formation of24 has been established by deuteration studies. Benzylidene benzoxazinone41 is obtained from dibromocinnamamide14 and propiolamide40. Dichloracetamides8 and10 undergo interesting ring closure to compounds45–54 upon treatment with amines. The course of electrophilic reactions of the lactams depends upon the ring size. Contribution No. 18 from Searle R & D Centre Presented at a symposium to felicitate Prof N S Narasimhan at the University of Poona, November 18–19, 1988     

New polymorphs of curcumin

Two new crystalline polymorphs and an amorphous phase of the active curcuminoid ingredient in turmeric are reported. Curcumin polymorph 2 has higher dissolution rate and better solubility than the known polymorph 1.     

Effects of dipolar interactions on linear and nonlinear optical properties of multichromophore assemblies: a case study

Interchromophore interactions in flexible multidipolar structures for nonlinear optics were addressed by a combined experimental and theoretical study on two series of one-, two-, and three-chromophore systems in which identical push-pull chromophores are assembled through covalent and flexible linkers in close proximity. The photophysical and nonlinear optical properties (quadratic hyperpolarizability) of the multichromophore systems were investigated and compared to those of the monomeric chromophores. Multimers have larger dipole moments than their monomeric analogues, that is, the dipolar subchromophores self-orientate within the multimeric structures. This effect was found to depend on the intersubchromophore distance in a nontrivial manner, which confirms that molecular engineering of such flexible systems is more complex than in completely geometrically controlled systems. Electric-field-induced second-harmonic generation (EFISHG) measurements in solution revealed increased figures of merit as compared to the monomeric analogue. This effect increases with increasing number and polarity of the individual subchromophores in the nanoassembly and increasing spacing between dipolar subchromophores. Experimental results are interpreted by a theoretical model for interacting polar and polarizable chromophores. The properties of multidipolar assemblies are shown to be related to the relative orientation of chromophores, which is imposed by interchromophore interactions. The supramolecular structure is thus a result of self-organization. The proposed theoretical model was also used to predict the properties of multichromophore structures made up of more polar and polarizable push-pull chromophores, and showed that stronger interchromophore interactions can heavily affect the individual optical responses. This suggests new routes for engineering highly NLO responsive multichromophore systems.     

A Facile Synthesis of Novel (Z)‐ethyl‐3‐(5‐substituted‐1‐alkyl/aryl‐1H‐indol‐3‐yl)‐2‐(1H‐tetrazol‐5‐yl)acrylate

A novel route was developed for synthesis of high potential 1H‐tetrazoles by using conventional method. Tetrazole scaffold is a promising pharmacophore fragment, frequently used in the development of various novel drugs. Here, the novel (Z)‐3‐(N‐alkyl‐indol‐3‐yl)‐2‐(1H‐tetrazole‐5‐yl)acrylates 5 ( a – i ) have been synthesized from (Z)‐ethyl‐3‐(1H‐indol‐3‐yl)2‐(1H‐tetrazol‐5‐yl)acrylates 4 ( a – c ) by using various alkylating agents such as Dimethyl Sulphate (DMS), Diethyl Sulphate (DES), and benzyl chloride; 4 ( a – c ) were synthesized from sodium azide in the presence of copper sulfate in dimethylformamide; 3 ( a – c ) have been prepared by Knoevenagel condensation of indole‐3‐carbaldehyde 1 ( a – c ) and ethylcyanoacetate 2 in the presence of L‐Proline as a catalyst at room temperature in ethanol for an hour. This is an efficient and clean click chemistry method that has various advantages such as easy workup, higher yields, shorter reaction times, and more economical.     

Multiscale modelling strategies and experimental insights for the solvation of cellulose and hemicellulose in ionic liquids

ABSTRACT

The present study investigates the dissolution behaviour of cellulose and hemicellulose in potential ionic liquids (ILs) using both the quantum chemical and experimental validation. For converging upon the recommended IL, 1428 ILs consisting of 42 cations and 34 anions were studied with the conductor like screening model for real solvents (COSMO-RS) model. Based on the infinite dilution activity coefficient of the components in IL, the selected anions and cations were visualised by observing their interactions with cellulose and hemicellulose using interaction energies, natural bonding orbital analysis and molecular dynamics simulations. The dissolution order of cellulose and hemicellulose in ILs was primarily determined by the evaluation of hydrogen bonds between the oxygen atom of anion and hydroxyl proton of cellulose/hemicellulose. From this discernible fact, the anion of the IL was observed to play a leading role in the solvation process as compared to the cation. Eventually, acetate [OAc]^– anion and 1-ethyl-3-methylimidazolium [EMIM]⁺ cation were found to be good candidates for the dissolution of cellulose and hemicellulose. This was further confirmed by the measurement of solid-liquid equilibria with cellulose and hemicellulose. The regenerated cellulose powder was then characterised by Fourier transform spectroscopy(FTIR), X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA).     

Study on linear and nonlinear stability analysis of double diffusive electro-convection in couple stress anisotropic fluid-saturated rotating porous layer

The influence of rotation and electric field on the onset of double-diffusive convection in rotating anisotropic couple stress fluid embedded porous media, which is caused by the combined action of external AC electric field and heating from below, has been investigated in this study. The associated equations were solved using the normal mode technique in conjunction with the modified Brinkman model, with free-free and rigid-rigid boundary conditions. Solute concentration and temperature are treated as independent parameters for the two diffusive components. Finally, neutral stability curves have been sketched to show how various flow parameters affect neutral stability. It is noticed that electric field has destabilizing effect on thermodynamic convection while rotation couple stress parameters have a tendency to stabilize the physical system under consideration. Furthermore, heat and mass transport have been studied using non-linear analysis in unsteady case. It is found that rotation, couple stress, porous parameters has influence of declining heat and mass transport while electric and anisotropic parameters have effect of boosting up heat and mass transport.     

FeIII–Salen-Based Probes for the Selective and Sensitive Detection of E450 in Foodstuff

Inorganic pyrophosphate (PPi) is considered as a diagnostic marker for various diseases such as cancer and vascular calcification. PPi also plays an important preservative role as an additive E450 in foodstuff. In this work, a selective Fe^III–salen-based probe for PPi is described; this probe disassembles in the presence of the target analyte into its molecular blocks, 1,2-propanediamine and 3-chloro-5-formyl-4-hydroxybenzenesulfonic acid. The latter signaling unit leads to a fluorometric response. Compared with a related prototype, the new complex shows a 2.3-times stronger emission at 500 nm and a 155-times better selectivity of PPi over adenosine triphosphate (ATP). Importantly, the new probe was successfully applied for detecting E450 in foodstuff.     

Transformation of Terminal Diols of Cyclic and Acyclic Saccharides to Epoxides and Alkenes by Reaction with Triphenylphosphine,Imidazole and Iodine

ABSTRACT

Reaction of various terminal diols 1,4,6,8-12, derived from cyclic and acyclic monosaccharides, with 2 mol equivalents each of TPP-imidazole-I₂ between -8 °C and 15 °C in THF afforded the corresponding epoxides 2,5,7,13-17, respectively, with 4 mol equivalents each of TPP-imidazole-I₂ in toluene at reflux temperature the starting diols afforded the corresponding alkenes 3,18-24, respectively.