Unusual products of oxidation with Cr(VI) of methyl 5-methyl-7-methoxy-8-isopropyl-3,4-2-naphthoate

Abstract is not available.

Strategies of synthesis of aromatic polyketides using cyclohexa-1,4-and-1,3-dienes in Alder Rickett reactions

Cyclohexa-1, 4-dienes with appropriate substituents, obtained by birch reduction of the substituted benzene, react directly with derivatives of propiolic ester or aldchyde to yield aromatic polyketides. The following compounds have been synthesized; mycophenolic acid, nidulol methyl other, the root growth hormone 3, 5-dihydroxy-2-formyl-4-mythyl-benzoic acid, antibiotic DB 2073, the macrocyclic lactones lasiodiplodin and dihydrozearalenone and the biphenyl derivatives alternario and altenusin. Polyketide anthraquinones can be made from naphthoquinone precursors.

Structure of (4S)-2,4-dimethyl-1,2-dihydropyrazino[2,1-b]quinazoline-3(4H),6-dione

C13HI3N302, orthorhombic, P2~2121, a = 17.443 (5), b = 11.650 (4), c = 5.784 (1)/~, Z = 4, d m = 1.456, d c = 1.429 Mg m -3, F(000) = 512, g(Cu Ka) = 0.843 mm-L The R index is 0.040 for 1358 significant reflections. The structure is stabilized by C-H...O interactions. The N-methylated eis peptide group which forms part of a six-membered ring is non-planar. The torsion angle about the peptide bond is -6.1 (4) ° and the peptide bond length is 1.337 (3) A.

An essential arginine residue at the substrate binding site of 4-hydroxyisophthalate hydroxylase.

4-Hydroxyisophthalate hydroxylase was inactivated by treatment with phenylglyoxal by a process obeying pseudo-first order kinetics indicating the presence of an essential arginine located presumably in the active site. Addition of saturating amounts of 4-hydroxyisophthalate during the treatment resulted in complete protection of the enzyme from the inactivation, but addition of NADPH was totally ineffective. Analysis of the effect of various substrate analogs on the protection of the enzyme showed that carboxyl and hydroxyl groups at para positions on the aromatic ring are essential for substrate binding to the active site. It was also observed that analogs which protect the enzyme against phenylglyoxal inactivation are themselves effective inhibitors of the enzyme activity.

Biochemical effects of 3,5-diethoxycarbonyl-1, 4-dihydrocollidine in mouse liver

3,5-Diethoxycarbonyl-1,4-dihydrocollidine (DDC) is a porphyrinogenic agent and is a powerful inducer of δ-aminolaevulinate synthetase, the first and rate-limiting enzyme of the haem-biosynthetic pathway, in mouse liver. However, DDC strikingly inhibits mitochondrial as well as microsomal haem synthesis by depressing the activity of ferrochelatase in vivo. The drug on repeated administration to female mice has been found to elicit hypertrophic effects in the liver microsomes initially, but the effects observed at later stages denote either hyperplasia or increase in polyploidal cells. The microsomal protein concentration shows a striking decrease with repeated doses of the drug. The rate of microsomal protein synthesis in vivo as well as in vitro shows an increase with two injections of DDC but decreases considerably with repeated administration of the drug. The activities of NADPH-cytochrome creductase and ribonuclease are not affected in the liver microsomes of drug-treated animals when expressed per mg of microsomal protein. DDC has also been found to cause degradation of microsomal haem, which is primarily responsible for the decrease in cytochrome P-450 content. The drug also leads to a decrease in mitochondrial cytochrome c levels due to inhibition of haem synthesis and also due to degradation of mitochondrial haem at later stages. The biochemical effects of the drug are compared and discussed with those reported for allylisopropylacetamide and phenobarbital.

Crystal and molecular structure of a dimethyl sulphoxide complex with lanthanum nitrate, La(NO3)3.4(CH3)2SO

Abstract is not available.

Synthesis of 4,6-(and 5,7-)dimethoxy-3,3-dimethyl-1-indanones

Grignard reaction of ethyl 3-(3,5-dimethoxyphenyl)-propionate (4) followed by cyclodehydration of the carbinol (5) with conc H2SO4 gave 4,6-dimethoxy-3,3-dimethylindane (6). Oxidation of the indane (6) with CrO3-pyridine complex in methylene chloride gave 4,6-dimethoxy-3,3-dimethylindan-1- one (1) in high yield. Conjugate addition of methyl magnesium iodide to methyl α-cyano-β-methyl-3,5-dimethoxycinnamate (11), prepared from 3,5-dimethoxyacetophenone (10) by Knoevenagel condensation, resulted in methyl 2-cyano-3-(3,5-dimethoxyphenyl)-3,3-dimethylpropionate (12). Refluxing the ester (12) with aq DMSO containing sodium chloride gave the corresponding nitrile (15) which underwent Höesch reaction to yield 5,7-dimethoxy-3,3-dimethylindan-1-one (2).

Zeeman effect of nuclear quadrupole resonance in 1-chloro-2,4-dinitrobenzene

The Zeeman effect of NQR was studied in 1-chloro-2,4-dinitrobenzene. A low value of the asymmetry parameter (0.10) was obtained. Four physically inequivalent field gradients were located and their orientations in the crystallographic abc system were determined using symmetry considerations. From these data the orientations of the molecules in the unit cell were determined. The results agree well with the two-dimensional x-ray structural data. The bond characters of the C[Single Bond]Cl bond were calculated, and the values compare well with those generally obtained for C[Single Bond]Cl bonds in chlorine derivatives of benzene. ©1973 The American Institute of Physics.

Mandelic acid-4-hydroxylase, a new inducible entyme from Image

A soluble fraction of Image catalyzed the hydroxylation of mandelic acid to Image -hydroxymandelic acid. The enzyme had a pH optimum of 5.4 and showed an absolute requirement for Fe2+, tetrahydropteridine, NADPH. Image -Hydroxymandelate, the product of the enzyme reaction was identified by paper chromatography, thin layer chromatography, UV and IR-spectra.

oxidation of catechol in plants iv. purification and properties of the 3,4,3',4'-tetrahydroxydiphenyl-forming enzyme system from tecoma leaves

Acetone powders prepared from leaf extracts of Tecoma stans L. were found to catalyze the oxidation of catechol to 3,4,3',4'-tetrahydroxydiphenyl. Fractionation of the acetone powders obtained from Tecoma leaves with acetone, negative adsorption of the acetone fraction with tricalcium phosphate gel, and chromatography of the gel supernatant on DEAE-Sephadex yielded a 68-fold purified enzyme with 66% recovery. The enzyme had an optimum pH around 7.2. It showed a temperature optimum of 30° and the Km for catechol was determined as 2 x 10-4 m. The purified enzyme moved as a single band on polyacrylamide gel electrophoresis. Its activity was found to be partially stimulated by Mg2+. The reaction was not inhibited by o-phenanthroline and agr,agr'-dipyridyl. The purified enzyme was highly insensitive to a range of copper-chelating agents. It was not affected appreciably by thiol inhibitors. The reaction was found to be suppressed to a considerable extent by reducing agents like GSH, cysteine, cysteamine, and ascorbic acid. The purified enzyme was remarkably specific for catechol. Catalase affected neither the enzyme activity nor the time course of the reaction. Hydrogen peroxide was not formed as a product of the reaction.

Structure of pentacyclo[7.4.2.02,6.06,15.011,14]pentadec-4-ene-7,13-dione, a novel pentacyclic C15 quinane system

C 15H 1602 (a synthetic precursor to dodecahedrane), monoclinic, P21/n, a = 12.171 (5), b = 6.976(5), c = 13.868 (3) A, B = 102.56 (3) ° , Z = 4, D m = 1.30, D c = 1.318 g cm -3, F(000) = 488, g(Mo K¢t) = 0.92 cm- 1. Intensity data were collected on a Nonius CAD-4 diffractometer and the structure was solved by direct methods. Full-matrix least-squares refinement gave R = 0.077 (R w = 0.076) for 1337 observed reflections. All the five-membered rings are cis fused and have envelope (C s symmetry) conformations.

Crystallization Kinetics and Electrical Relaxation of BaO-0.5Li(2)O-4.5B(2)O(3) Glasses

Transparent glasses in the composition BaO-0.5Li(2)O-4.5B(2)O(3) (BLBO) were fabricated via the conventional melt-quenching technique. X-ray powder diffraction combined with differential scanning calorimetric (DSC) studies carried out on the as-quenched samples confirmed their amorphous and glassy nature, respectively. The crystallization behavior of these glasses has been studied by isothermal and nonisothermal methods using DSC. Crystallization kinetic parameters were evaluated from the Johnson-Mehl-Avrami equation. The value of the Avrami exponent (n) was found to be 3.6 +/- 0.1, suggesting that the process involves three-dimensional bulk crystallization. The average value of activation energy associated with the crystallization of BLBO glasses was 317 +/- 10 kJ/mol. Transparent glass-ceramics were fabricated by controlled heat-treatment of the as-quenched glasses at 845 K/40 min. The dielectric constants for BLBO glasses and glass-ceramics in the 100 Hz-10 MHz frequency range were measured as a function of the temperature (300-925 K). The electrical relaxation and dc conductivity characteristics were rationalized using electric modulus formalism. The imaginary part of the electric modulus spectra was modeled using an approximate solution of the Kohlrausch-Williams-Watts relation. The temperature-dependent behavior of stretched exponent (beta) was discussed for the as-quenched and heat-treated BLBO glasses.

Structure of ethyl 1,2,2-tricyano-3-(4-nitrophenyl)-cyclopropane-1-carboxylate

C15HIoN404, monoclinic, P2~/c, a = 10.694(8), b = 11.743 (8), c - 12.658 (8) A, fl = 113.10 (7) °, V = 1462.1 A 3, Z = 4, O m = 1 "38, O c = 1.408 g cm -3, t,t(MoKa, ~, = 0.7107 ]~) = 0.99 cm -i, F(000) = 640. The structure was solved by direct methods and refined to an R value of 0.054 using 1398 intensity measurements. The relative magnitudes of interaction of the substituents and the extent to which a ring can accommodate interactions with substituents are discussed.

Amine biosynthesis in Lathyrus sativus seedlings

The biosynthesis of certain amines in Lathyrus sativus seedlings was studied in isolated shoots and cotyledons. In shoots, arginine was about 14 times more efficient than ornithine for the synthesis of agmatine, putrescine, spermidine and spermine. Isotope dilution experiments, and the changes in specific activities of the 4 amines with time when 14C-arginine served as the precursor, indicated that putrescine and the polyamines were formed mainly from arginine, via agmatine. Similar experiments showed that cadaverine was formed at least in part from homoarginine, though lysine was ca 4 times more effective as a precursor. The pattern of changes in specific activity of homoagmatine and cadaverine with time when 14C-homoarginine served as the precursor support the conclusion that homoarginine and arginine follow analogous metabolic routes in the biosynthesis of putrescine and cadaverine respectively.