Synthesis based on cyclohexadienes: Part 10 synthesis of 5,5-dimethyl-7-methoxy-4-oxatricyclo[4.3.1.0]decan-2-ones

Synthesis of 5, 5-dimethyl- 7-methoxy-4 -oxatricyclo[4,3,1,0(3,7)]- decan-2-one 3a, a novel heterocyclic ring system present in morellin 1, and its 3-substituted derivatives 3b-e, is described from the Diels-Alder adducts 7, available from 1-methoxycyclohexa-1,4-dienes 4. Two routes, which involved the halocyclisation and the oxidative addition, were investigated for the conversion of the adducts 7 into 3. While the halocyclisation method resulted in mixtures, excellent yields of the target molecule were obtained by the second method. Solvolysis of the bromoether 9 resulted in a mixture of rearranged products 10, 13, 15 and 16.

Synthesis of 5,5-Dimethyl-7-methoxy 4-oxatricyclo [4,3,1,03,7]decan-2-ones

Two new synthetic routes for the preparation of the title compound and its 3-substituted derivatives, a novel ring system present in morellin and other related natural products, are reported from the readily available dihydroanisoles.

Synthesis, Crystal Structure, and Magnetic Properties of a Ferromagnetically Coupled Angular Trinuclear Copper(11) Complex [Cu3(02CMe)4(bpy)s(HzO)](PF)62

The synthesis, X-ray crystal structure, and magnetic properties of an angular trinuclear copper(II) complex [Cu3(O2CMC)4(bpy)3(H2O)](PF6)2 (1), obtained from a reaction of Cu2(O2CMe)4(H2O)2 With 2,2'-bipyridine (bpy) and NH4PF6 in ethanol, are reported. Complex 1 crystallizes in triclinic space group P1BAR with a = 11.529(1) angstrom, b = 12.121(2) angstrom, c = 17.153(2) angstrom, alpha = 82.01(1)-degrees, beta = 79.42(1)-degrees, gamma = 89.62(1)-degrees, and Z = 2. A total of 6928 data with I > 2.5sigma(I) were refined to R = 0.0441 and R(w) = 0.0557. The structure consists of a trinuclear core bridged by four acetate ligands showing different bonding modes. The coordination geometry at each copper is distorted square-pyramidal with a CuN2O2...O chromophore. The Cu...Cu distances are 3.198(1) angstrom, 4.568(1) angstrom, and 6.277(1) angstrom. There are two monoatomic acetate bridges showing Cu-O-Cu angles of 93.1(1) and 97.5(1)-degrees. Magnetic studies in the temperature range 39-297 K show the presence of a strong ferromagnetically coupled dicopper(II) unit (2J = +158 cm-1) and an essentially isolated copper(II) center (2J' = -0.4 cm-1) in 1. The EPR spectra display an axial spectrum giving g(parallel-to) = 2.28 (A(parallel-to) = 160 X 10(-4) cm-1) and g(perpendicular-to) = 2.06 (A(perpendicular-to) = 12 X 10(-4) cm-1) for the normal copper and two intense isotropic signals with g values 2.70 and 1.74 for the strongly coupled copper pair. The structural features of 1 compare well with the first generation models for ascorbate oxidase.

A Crystallization Technique For the Enantiomer Resolution of Conglomerates- (+/-)-4-Methoxyphenyl 1-Phenylethyl Ketone

The sorting of crystals of (+/-)-4-methoxyphenyl 1-phenylethyl ketone into its enantiomers is facilitated by crystallisation in a cellular grid made of filter paper.

Enantioselective Synthesis of Possible Diastereomers of Heptadeca-1-ene-4,6-diyne-3,8,9,10-tetrol; Putative Structure of a Conjugated Diyne Natural Product Isolated from Hydrocotyle leucocephala

Enantioselective synthesis of possible diastereomers of heptadeca-1-ene-4,6-diyne-3,8,9,10-tetrol, a structure proposed for the natural product isolated from Hydrocotyle leucocephala is accomplished. The reported spectral data of the natural product did not match those of any of the isomers that were synthesized and established that the structure proposed for the natural product is not correct and requires revision.

4-Hydroxy-6-(4-methoxyphenyl)-4-phenyl-1,3-diazinane-2-thione

In the title compound, C17H18N2O2S, the 1,3-diazinane-2-thione ring system is not coplanar with the benzene ring and methoxyphenyl ring system, the dihedral angle between the planes being 65.58 (13) and 89.18 (10)degrees, respectively. The crystal structure is characterized by intermolecular O-H...S, N-H...S, N-H...O and C-H...S hydrogen bonding.

Enantioselective synthesis of both (+)- and (-)-derivatives of bicyclo[4.3.0]nonan-8-one and 3,8-diones from R-carvone

Enantioselective synthesis of both the enantiomeric forms of the hydrindane derivatives mentioned in the title, potential chiral precursors in terpenoid synthesis, starling from R-carvone employing two different cyclopentannulation methodologies is described.

Exceptionally long crystal formation from 4-(3-bromopropyloxy)salicylaldehyde. X-ray crystallographic investigation

Unusually long (>14 cm) crystalline needles grow from 4-(3-bromopropyloxy)salicylaldehyde 1 presumably as a consequence of Br ... Br interactions; the powdered form of 1 shows one order of magnitude greater SHG activity realtive to urea.

Linear electro-optic effect and temperature coefficient of birefringence in 4-nitro-4script-methylbenzylidene aniline single crystals

A study of the linear electro?optic effect in single crystals of the organic compound, 4?nitro�4??methylbenzylidene aniline is reported. The reduced half?wave voltages have been found to have values 2.8, 1.3, and 1.1 kV at 632.8, 514.5, and 488.0 nm, respectively and the corresponding values of the largest linear electro?optic coefficient have been calculated. The thermal variation of the birefringence has also been investigated and the temperature variation of the refractive index difference is found to have the value, d?n/dT = 15.8 × 10?5 K?1.

Influence of poling methods on the orientational dynamics of 2-methyl-4-nitro-aniline in poly(methyl methacrylate) studied by second harmonic generation

The magnitude and stability of the induced dipolar orientation of 2-methyl-4-nitroaniline (MNA)/poly(methyl methacrylate) (PMMA) guest/host system is investigated. The chromophores are aligned using both the corona discharge and contact electrode poling techniques. The magnitude of order parameter (also an indicator for the second order nonlinear susceptibility) is measured by recording absorbances of the poled (by the two different techniques) and unpoled PMMA films at different concentrations of MNA. Under the same conditions the corona poling technique creates a higher alignment of molecules along the field direction. The time dependence of the second harmonic intensity of the MNA/PMMA film prepared by the two techniques can be described by a Kohlrausch-Williams-Watts stretched exponential. The temperature dependence of the decay time constant is found to generally follow a modified Williams-Landel-Ferry (WLF) or Vogel-Tamann-Fulcher (VTF) equation. The glass transition temperature seems to be the single most important parameter for determining the relaxation time tau(T).

Mechanism of growth inhibition of intraerythrocytic stages of Plasmodium falciparum by 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR)

Purine nucleotide synthesis in Plasmodium falciparum takes place solely by the purine salvage pathway in which preformed purine base(s) are salvaged from the host and acted upon by a battery of enzymes to generate AMP and GMP. Inhibitors of this pathway have a potent effect on the in vitro growth of P. falciparum and are hence, implicated as promising leads for the development of new generation anti-malarials. Here, we describe the mechanism of inhibition of the intraerythrocytic growth of P. falciparum by the purine nucleoside precursor, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR). Our results show that AICAR toxicity is mediated through the erythrocyte in which AICAR is phosphorylated to its nucleotide, ZMP. Further, purine metabolite labeling of the parasitized erythrocytes by H-3]-hypoxanthine, in the presence of AICAR, showed a significant decrease in radioactive counts in adenylate fractions but not in guanylate fractions. The most dramatic effect on parasite growth was observed when erythrocytes pretreated with AICAR were used in culture. Pretreatment of erythrocytes with AICAR led to significant intracellular accumulation of ZMP and these erythrocytes were incapable of supporting parasite growth. These results implicate that in addition to the purine salvage pathway in P. falciparum, AICAR alters the metabolic status of the erythrocytes, which inhibits parasite growth. As AICAR and ZMP are metabolites in the human serum and erythrocytes, our studies reported here throw light on their possible role in disease susceptibility, and also suggests the possibility of AICAR being a potential prophylactic or chemotherapeutic anti-malarial compound. (C) 2011 Elsevier B.V. All rights reserved.

Cyclopentaannulation of allyl alcohols via a radical cyclisation reaction. Total synthesis of 4-epibakkenolide-A

A four step cyclopentaannulation methodology starting from allyl alcohols using 5-exo-trig radical cyclisation as the key reaction, and its application to the total synthesis of 4-epibakkenolide is described.

Reduction of quinolines to 1,2,3,4-tetrahydro derivatives employing a combination of NaCNBH3 and BF3.OEt(2)

A regiospecific reduction of quinolines (and 1,10-phenanthroline) into the corresponding 1,2,3,4-tetrahydro derivatives using a combination of sodium cyanoborohydride and boron trifluoride etherate in refluxing methanol is described. Under the same conditions indole and acridine reduced to the corresponding dihydroderivatives, whereas acyl group transfer from oxygen to nitrogen atom is also noticed in the case of 8-acyloxyquinolines.

Reactivity Of Pph3 Toward Ru2cl(O2cme)4 - Synthesis And X-Ray Crystal-Structure Of [Ru(O2cme)(Mecn)2(Pph3)2](Clo4)

A new ruthenium(II) complex of the type [Ru(O2CMe)(MeCN)2(PPh3)2](CiO4) (1) has been isolated from a reaction between Ru2Cl(O2CMe), and PPh3 in MeCN followed by the addition of NaClO4. The structure of 1 is determined by single crystal X-ray studies. The crystal belongs to the monoclinic space group C2/m with the following unit cell dimensions for the C42H39N2O6P2ClRu(M = 866.15): a = 23.295(1)angstrom, b = 23.080(1)angstrom, c = 9.159(1)angstrom, beta = 107.32(1)-degrees, V = 4701(1)angstrom3, Z = 4, D(c) = 1.224 gcm-3, lambda(Mo - K-alpha) = 0.7107 angstrom, mu(Mo - K-alpha) = 4.09 cm-1, T = 293K, R = 0.081 (R(w) = 0.094) for 2860 reflections with I greater-than-or-equal-to 3-sigma(I) and g = 0.015853. In the complex cation, the symmetry about the metal centre is essentially octahedral showing the presence of a chelating acetato, two cis-oriented MeCN and two trans-disposed PPh3 ligands. The mechanistic aspects of the core cleavage reaction are discussed.