Imino Diels–Alder adducts. XII. Two pyrano[3,2‐c]quinolines

The crystal structures of pyrano­quinolines 9‐fluoro‐5‐phenyl‐3,4,4a,5,6,10b‐hexa­hydro‐2H‐pyrano[3,2‐c]quinoline, C₁₈H₁₈FNO, and 9‐methyl‐5‐phenyl‐3,4,4a,5,6,10b‐hexa­hydro‐2H‐pyrano­[3,2‐c]quinoline, C₁₉H₂₁NO, are isomorphous. In both structures, the pyran ring is exo to the six‐membered N‐heterocyclic ring formed in the cyclo­addition step. The torsion angles across the phenyl linkage for the two structures are −91.2 (1) and −88.3 (2)°. The striking feature in both crystal packings is that they do not contain the expected conventional hydrogen bonds, in spite of the presence of good hydrogen‐bonding functionalities. Possible C—H⋯π inter­actions are, however, observed.     

Electron paramagnetic resonance and optical absorption spectra of Cr ions in cadmium phosphate glass

EPR and optical absorption investigations of chromium doped cadmium phosphate glass are carried out. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. From the results and analyses of the EPR and optical studies, the site symmetry of Cr³⁺ ion in the glass is ascribed to a distorted octahedron. The bonding parameters suggest the ionic nature of Cr³⁺ ion with the ligands.     

Heavy metal ion uptake properties of polystyrene-supported chelating polymer resins

Metal ion uptake properties of polystyrene-supported chelating polymer resins functionalized with (i) glycine, (ii) hydroxy benzoic acid, (iii) Schiff base and (iv) diethanol amine have been investigated. The effects of pH, time and initial concentration on the uptake of metal ions have been studied. The uptake of metal ion depends on pH. The resins are more selective at pH 10 for Pb(II) and Hg(II), whereas at pH 6 they are found to be Cd(II) and Cr(VI) selective. Metal ion uptake properties of resins follow Freundlich’s equation. The resins are recyclable and are therefore employed for the removal of heavy metal pollutants from industrial waste water.     

A Sensitive HPTLC method for Estimation of Swertiamarin in Enicostemma littorale Blume,Swertia chirata (Wall) Clarke,and in formulations containing E. littorale

JPC – Journal of Planar Chromatography – Modern TLC - Swertiamarin is a secoiridoid glucoside present in members of the Gentianaceae family, including Swertia chirata (Wall) Clarke, S....     

Asymmetric synthesis of α-hydroxy carboxylic acids: direct oxidation of chiral amide enolates using 2-sulfonyloxaziridines

The direct oxidation of chiral amide enolates to optically active mandelic acid using 2-sulfonyloxaziridine $\text{1}$ is described. The diastereoselectivity is counterion dependent.     

Mass spectral fragmentation patterns of heterocycles. IV . Tetracyclic phenothiazines. IX. Electron impact promoted mass spectral fragmentation of pyrrolo[3,2,1-kl]phenothiazine

The mass spectral fragmentation patterns of pyrrolo[3, 2, 1-kl]phenothiazine ( 1 ) and its 1, 10-dideuterioderi-vative [2] are reported. The site of deuterium substitution in 2 was established by examination of its ¹³C nuclear magnetic resonance spectrum. The heteroaromatic stability of 1 to electron impact is exemplified by the occurrence of the molecular ion as the base peak and the formation of a reasonably intense M²⁺ ion. An intense M-1 ion is also observed. The more abundant fragment ions appear to result from sulfur ionization. Fragment ions arising from ionization of the nitrogen constitute only a small fraction of the total ion current. Proposed fragmentation pathways of 1 are supported by the detection of appropriate metastable ions, exact mass measurements, and electron impact spectrum of 2 .     

Dimorphism in (2Z)‐2‐benzyl­idene‐N,7‐dimethyl‐3‐oxo‐5‐phenyl‐2,3‐dihydro‐5H‐1,3‐thia­zolo[3,2‐a]pyrimidine‐6‐carboxamide

The title compound, C₂₂H₁₉N₃O₂S, crystallizes in two polymorphic forms having the same space group, viz. P, with Z′ = 2 and Z′ = 1. In both polymorphs, the planar thia­zole ring is fused cis with the dihydro­pyrimidine ring, the carbamoyl group is in an extended conformation with an anti­clinal orientation with respect to the pyrimidine ring, and the phenyl ring is attached to the pyrimidine ring approximately at a right angle. The two polymorphs have different inter­planar angles between the phenyl and thia­zole rings. The mol­ecules are linked by N—H⋯O and C—H⋯O hydrogen bonds.     

A facile one‐pot synthesis of novel substituted 1,2,3,4‐tetrahydropyrimidine,part 2: Synthesis of 1‐(aralkyl/aryl)‐3‐(alkyl/aralkyl/aryl)‐5‐aroyl‐1,2,3,4‐tetrahydropyrimidines

1‐(Aralkyl/aryl)‐3‐(alkyyaralkyl)‐5‐aroyl‐1,2,3,4‐tetrahydropyrimidines ( 2a‐c ) have been synthesized by dethiomethylation of 5‐aroyl‐6‐methylthio‐1,2,3,4‐tetrahydropyrimidines ( 1a‐c ). An alternative one‐pot synthetic strategy has been developed for the title compounds 2a‐t by the reaction of enaminones 3 with pri mary amine and formaldehyde in refluxing methanol in good yields.