Application of Polyphosphoric Acid‐Mediated Acyl Migration for Regiospecific Synthesis of Diverse 2‐Acylpyrroles from Chalcones

A metal‐free approach for the synthesis of 2‐acylpyrroles is reported in this paper. Synthesis of the target molecule started from chalcones and was carried out in two steps. Initial step involved the conversion of chalcones to corresponding 4‐substituted‐3‐acylpyrroles by reaction with TosMIC. In the subsequent step, target molecules were obtained in modest to good yields by polyphosphoric acid‐mediated acyl rearrangement of 3‐acylpyrroles to their 2‐acyl congeners. The crucial final step was amenable to diverse substitutions on pyrrole ring. Preliminary experiment for the determination of mechanism indicated the involvement of acylium ion.     

Design and Synthesis of Aromatic Polyesters Bearing Pendant Clickable Maleimide Groups

A bisphenol bearing pendant maleimide group, namely, N‐maleimidoethyl‐3, 3‐bis(4‐hydroxyphenyl)‐1‐isobenzopyrrolidone (PPH‐MA) was synthesized starting from phenolphthalein. Aromatic (co)polyesters bearing pendant maleimide groups were synthesized from PPH‐MA and aromatic diacid chlorides, namely, isophthaloyl chloride (IPC), terephthaloyl chloride (TPC), and 50:50 mol % mixture of IPC and TPC by low temperature solution polycondensation technique. Copolyesters were also synthesized by polycondensation of different molar proportions of PPH‐MA and bisphenol A with IPC. Inherent viscosities and number‐average molecular weights of aromatic (co)polyesters were in the range of 0.52–0.97 dL/g and 20,200–32,800 g/mol, respectively indicating formation of medium to reasonably high‐molecular‐weight polymers. ¹³C NMR spectral analysis of copolyesters revealed the formation of random copolymers. The 10% weight loss temperature of (co)polyesters was found in the range 470–484 °C, indicating their good thermal stability. A selected aromatic polyester bearing pendant maleimide groups was chemically modified via thiol‐maleimide Michael addition reaction with two representative thiol compounds, namely, 4‐chlorothiophenol and 1‐adamantanethiol to yield post‐modified polymers in a quantitative manner. Additionally, it was demonstrated that polyester containing pendant maleimide groups could be used to form insoluble crosslinked gel in the presence of a multifunctional thiol crosslinker. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 630–640     

On almost pseudo-conformally symmetric Ricci-recurrent manifolds with applications to relativity

The object of the present paper is to study almost pseudo-conformally symmetric Ricci-recurrent manifolds. The existence of almost pseudo-conformally symmetric Ricci-recurrent manifolds has been proved by an explicit example. Some geometric properties have been studied. Among others we prove that in such a manifold the vector field ? corresponding to the 1-form of recurrence is irrotational and the integral curves of the vector field ? are geodesic. We also study some global properties of such a manifold. Finally, we study almost pseudo-conformally symmetric Ricci-recurrent spacetime. We obtain the Segre’ characteristic of such a spacetime.     

Efficient Approach to 4‐Benzyl‐5,5‐dimethyldihydrofuranones: Total Synthesis of (±_bold;)‐Solafuranone

A six‐step general and very efficient synthesis of 4‐(arylmethyl)‐5,5‐dialkyldihydrofuranones starting from corresponding aryl aldehyde has been developed. Solafuranone, a novel furanone isolated from the Chinese folk medicine Solanum indicum, has been accomplished starting from 2,6‐dimethylbenzaldehyde in six steps in an overall yield of 70%. Contrary to expectations, solafuranone and its analogue failed to exhibit any significant cytotoxicity against A549 (lung adenocarcinoma) and HL60 (leukemia cells) cell lines.     

Zinc triflate catalyzed acylation of alcohols,phenols, and thiophenols

An expedient procedure for the acylation of alcohols, phenols, and thiophenols using catalytic amount of Zn(OTf)₂ is described. This procedure is highly suitable for industrial application due to use of less toxic metal as a part of catalyst, short reaction time at ambient temperature, without any racemization of chiral alcohols.     

One‐pot direct synthesis of fluorescent polyaniline‐porphyrin macrospheres from porphyrin

Porphyrins are very important chromophores as sensitizer in solar cell. Hole and electron transport layers are being used as an important layer to move the electrons and holes away from the sensitizer molecule to electrodes. In this work, a simple process has been developed for the synthesis of one layer combination of sensitizer and hole transport, that is, polyaniline‐porphyrin (PANI‐TPPS₄) system as a bulk heterojunction. Macrospheres of fluorescent PANI‐TPPS₄ materials were synthesized by one‐pot as well as two step processes directly from porphyrin for the first time. The advantage of this process is no need to isolate sulfonated porphyrin (TPPS₄), which is a difficult process. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Self-assembled networks of ribbons in molecular hydrogels of cationic deoxycholic acid analogues

Aqueous gels derived from three cationic 24-nor 3,12-dihydroxy cholane (DC) derivatives with N-methyl-2-pyrrolidinone (NMP), N-methylmorpholine (NMM), and 1,4-diazabicyclo[2.2.2]octane (DABCO) at the side chain positions have been exhaustively characterized by small-angle neutron-scattering experiments. Although the molecular structures differ slightly by the heterocycle grafted to the steroid core, the derived gels exhibit a range of structural behaviors at the nanoscale that depart from those observed with simple deoxycholate systems. The NMM-DC aggregates are ribbons with a bimolecular thickness of t = 37 A and an anisotropy of the section b/a approximately 0.1. DABCO-DC exhibits a remarkable transition from ribbons (t = 29.5 A, b/a = 0.18) to thicker cylindrical fibers (R approximately 59 A), involving four original ribbons, upon a concentration increase. The NMP-DC system forms thick cylindrical fibers (R approximately 68 A) with steroid molecules organized in a specific morphology. Bilayered or interdigited structures are formed and favored by the presence of multiple polar interaction centers in the DC molecules. Secondary aggregation mechanisms are invoked in the formation of bundles having a lower cross-sectional anisotropic symmetry and exhibiting Bragg peaks corresponding to molecular length periodicities. The relations between the structural information and the rheological properties are discussed.     

A simple construction of a bile acid based dendritic light harvesting system

[structure: see text] A facile synthesis of a cholic acid derived dendritic structure labeled with nine naproxens and a single anthracene is reported. This multichromophoric, novel dendritic construct acts as an efficient molecular light harvester.     

On ø-quasiconformally symmetric Sasakian manifolds

We study locally and globally ø-quasiconformally symmetric Sasakian manifolds. We show that a globally ø-quasiconformally symmetric Sasakian manifold is globally ø-symmetric. Some observations for a 3-dimensional locally ø-symmetric Sasakian manifold are given. We also give an example of a 3-dimensional locally ø-quasiconformally symmetric Sasakian manifold.