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The heterogeneous catalytic transformations of several 1,3-aminoalcohols on copper and copper chromite catalysts have been investigated. 1,3-Aminoalcohols obtained by the reduction of Mannich bases were selectively transformed into ketones, while others having either a tertiary hydroxy group or an amino group attached to a tertiary carbon underwent fragmentation. The mechanisms of these processes are discussed in connection with the molecular structures.

The asymmetric reduction of steroid 17- and 20-ketones with chiral hydrosilanerhodium-(+)- and (−)-diop-complex catalysts allows different stereoselectivities in the formation of 17-alchols, but not of 20-alcohols. The degree of this stereoselectivity is higher than that attained with other methods. The stereoselectivity can be explained in terms of the most preferred conformation of the α-siloxysteroid-rhodium intermediate complexes.

Dedoublement optique de la benzylamino-2 methoxy-8 tetraline, intermediaire synthetique de l'hydroxy-8 dipropylamino-2 tetraline. Les enantiomeres de ce dernier sont analyses par chromatographie paire ion et on en etudie la configuration absolue par diffraction RX

Le TCNE, la dichloro-2,3 dicyano-5,6 benzoquinone et le dicyano fumarate de diethyle reagissent avec les composes du titre pour donner des derives de l'acide cyclopropanedicarboxylique-1,1 et de l'acide norcarene-3 dicarboxylique-7,7

Etude de l'oxydation electrochimique de l'isopropyl-4 anisole dans l'acide trifluoroacetique

Synthese de bis-bromomethyl-2,6 bromo-4 pyridine (A) a partir d'acetyl-3 dihydro-3,4 methyl-6 pyrannedione-2,4 ou d'acide hydroxy-4 pyridinedicarboxylique-2,6; A reagit avec l'imino-2,2' bis-acetate de di-t-butyle puis avec l'ethynylbenzene pour donner le compose du titre

A gas electron diffraction study of 2-methyloxacyclobutane has been carried out at room nozzle temperature. The four membered ring takes a planar conformation. The mean ra values for the O-C, C-C and C-H bonds are 1.448(5)A, 1.534(4)A and 1.118(3) Å, respectively. The endocyclic bond angles are C-C-C = 85.5(18)° and C-C-O=91.2 (15)°, while the angle C-O-C was assumed to be 92°. The position of exocyclic carbon atom was characterized, in addition by < Cexocyclic-C-O = 110.7(7)° and torsional angle Cexocyclic-C-O-C = 59.6(40)° (0° corresponds to the anti position of Cexocyclic-C and O-C bonds).

Rose Bengal mediated photooxidation of mitochondrial F1-ATPase and its beta-subunit resulted in inactivation and loss of about 50 and 60% of their histidine residues, respectively. The beta-subunit was not cleaved upon photooxidation. Photooxidation of histidine probably results in changes in the conformational stability of F1-ATPase leading to its inactivation. The participation of singlet molecular oxygen during the photooxidation process is suggested by the selective loss of histidine residues, while other amino acids, also sensitive to singlet oxygen attack, were not affected. Photochemical damage of F1-ATPase was prevented by various phenanthroline compounds, the order of efficiency being bathophenanthroline-Fe chelate greater than bathophenanthroline greater than orthophenanthroline-Fe chelate greater than bathophenanthroline-sulfonate-Fe chelate. The prevention by bathophenanthroline-Fe chelate of photochemical damage is interpreted on the basis of its interaction with the photosensitizer, Rose Bengal, probably implying a chemical reaction which decreases the actual concentration of the sensitizer and, thereby, the extent of photoinactivation.

On various transition metal catalysts (Raney nickel, Pd/C, Pd black, RuO2, Rh/C), the N-C(2) bond in N-benzoyl-2,2,4,4-tetraMe-azetidin-3-one (1) undergoes hydrogenolysis with 100% selectivity, as does that in the corresponding azetidine derivative 2 on Raney nickel; in the process, the oxo group in the ring in 1 is converted to a hydroxy group. In the analogues with higher numbers of ring atoms, only the latter hydrogenation proceeds; under identical reaction conditions, C-N hydrogenolysis does not occur. The rate of hydrogenolysis is increased by the carbonyl group at position 3 in azetidinone, as compared to that of azetidine, which does not possess the carbonyl function. A proposal is made concerning the reaction mechanism.

Preparation d'enaldehydes par reaction d'aldehydes ou de cetones avec le (cyclohexylimino-4 butene-2yl O,O-diethyl) phosphonate qui est prepare a partir de l'acetate de diethoxyphosphoryl-4 butene-«2»yle

Synthese du compose du titre par reaction de l'ethynyl aniline avec le phenyl-3 dimethyl-2,2 propyne-2ol-1

The role of diethylamine in the transformation of 1,3-butanediol on a copper catalyst was investigated and interpreted. In the presence of increasing amounts of diethylamine, somewhat more 2-butanone was observed to form, but the overall effect was reduced by side-reactions.

The transformations of 13 alcohols and 13 diols in the presence of a small amount dimethylsulfoxide (1/16 mol) were studied. Relationships were found between the type of the hydroxy compound and the selectivity of the transformation, and conclusions were drawn regarding the transformation mechanism. The ether formation observed with certain alcohols proceeds via a carbenium cation. The reaction conditions applied were found suitable for inducing water elimination from the ditertiary 1,2- and 1,3-diols (pinacol rearrangement, 1,2-elimination). From the 1,4- and 1,5-diols the corresponding oxacycloalkanes can be obtained in good yield. Cyclodehydration occurs by intramolecular nucleophilic substitution, via a concerted mechanism. The effect of DMSO is exerted directly, and protoncatalysis occurs simultaneously.

Les derives marques des O-methyl-1 isomaltoside, O-methyl-1 maltoside, et du di-O-α-D-glucopyranosyl-4,6 O-methyl-1 glucopyranoside sont synthetises a partir des composes marques anhydro-1,6 correspondants. Leur spectre RMN a 500 MHZ est effectue

The isomerization of six 5- and 6-membered 1,3-oxazacycloalkanes (3-methyl- and 2-alkyl-3-methyl-substituted oxazolidines and tetrahydro-1,3-oxazines) to the corresponding carboxamides on a palladium catalyst has been established. From the results of isotope exchange, catalytic and stereo-chemical studies, a reaction mechanism is proposed to interpret this new catalytic process which involves the dissociative adsorption of the oxazacyclo-alkanes on C-2, followed by ring opening via the attack of an adsorbed hydrogen atom on ring carbon C-5 (or C-6).

The transformations of the condensed-skeleton β-lactams (azetidin-2-ones) 1 – 4 were studied under various reductive conditions. On the action of a complex metal hydride, selective formation of azetidines occurs. A new heterogeneous catalytic method is reported, which is suitable for the preparation of cyclic 1,3-aminoalcohols in the presence of Raney Ni in liquid-phase hydrogenation. On a Ni on Cab-O-Sil ® catalyst in a flow reactor, 1 is converted to the carboxylic acid amide 9 with high selectivity.

The possibilities of formation of the CO infrared absorption doublet were examined by transmission infrared spectroscopy, in the frequency interval for CO chemisorbed in linear form (2100-2000 cm−1 on variously treated 5% PtCab-O-Sil catalysts. The resolution of the doublet at about 2070 and 2050 cm−1 was not very good for a freshly reduced sample. Treatment in CO or O2 promoted formation of the doublet, whereas surface hydrogen completely inhibited it. A CO doublet could not be produced on a sample which had been used several times in CO + O2 reaction cycles. The surface CO layers relating to the CO doublet exhibited different reactivities toward O2 at 298 K. In separate runs, in response to 10 Torr H2 at 298 K, the position of the low-frequency (desorptive) CO band shifted from 2052 to 2061 cm−1, while that of the high-frequency (adsorptive) band underwent a red shift, from 2072 to 2068 cm−1.

The dehydration of various aliphatic 1,3-diols involving oxo compound formation has been studied in the vapour phase at 250 - 300 °C on Rh/Al 2 O 3 and Rh/Cab-O-Sil catalysts, and in the liquid phase at 100 °C in the presence of RhCl 3 /PPh 3 . Mechanisms of oxo compound formation have been investigated and compared. It has been established that the transoformation proceeds in the same manner for both catalyst types, via dehydrogenation/hydrogen transfer and dehydration reaction steps.

Copper-on-silica gel catalysts prepared by ion exchange exhibit a unique activity in the isomerization of alkenes that are able to form the most stable tertiary carbocations. Poisoning experiments with pyridine and 2,6-dimethylpyridine, together with IR studies, indicate the presence of different surface acidic sites generated during the activation of the catalysts, inducing an ionic-type isomerization.

When 1-anilino-8-naphthalenesulfonate (ANS) interacts with phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) its fluorescence is enhanced and a blue shift occurs. There is evidence that ANS binds to the site of the nucleotide substrate. The work described herein shows that when various anion inhibitors are added to the ANS-enzyme solution, de-enhancement of the fluorescence occurs. Extrapolation to infinite anion concentration shows that pyruvate ions are the most effective quenchers (ca. 90%) and nitrate ions the least effective, sulfate and phosphate ions being intermediate. The results are consistent with earlier enzymes kinetic findings suggesting that pyruvate ions and ANS, both competing with the nucleotide substrate, are able to bind to the enzyme simultaneously and that sulfate, phosphate and nitrate ions can, to various extents, affect the properties at the active centre of phosphoglycerate kinase via conformational changes without sharing ligands with the nucleotide substrate.

Syntheses a partir de la chloration de salicylaldoxime suivie de cycloaddition de styrene ou d'ethynylbenzene puis de reduction et cyclisation des isoxazoles formes

The rates of hydrogenolysis and isomerization of methyloxirane, cis- and trans-2,3-dimethyloxirane and 2-methyloxetane were studied on a Pt C catalyst, as functions of the hydrogen pressure and the temperature. A new phenomenon was observed in the case of 2-methyloxetane: the change in mechanism as the temperature was elevated led to a change in regioselectivity. There is no such effect for methyloxirane, for which the dissociative mechanism is not competitive at high hydrogen pressure. Likewise, the mechanisms of transformation of methyloxirane and the 2,3-dimethyloxiranes are not the same. Methyloxirane probably participated in edgewise adsorption on the surface of the catalyst, while cis-2,3-dimethyloxirane undergoes flat adsorption.

The adsorption of NO on Pt/SiO/sub 2/ has been studied by infrared spectroscopy. Three distinct surface species are proposed. A high-frequency band centered between 1770 and 1800 cm/sup -1/ is assigned to an NO species linearly adsorbed on the rough open crystal planes of Pt. The absorption frequency of this band was observed to decrease with increasing surface coverage. A low-frequency band centered between 1570 and 1600 cm/sup -1/ is assigned to bridge-bonded NO. The absorption frequency of this band was observed to increase with increasing NO surface coverage. Prolonged pretreatment in H/sub 2/ at 673 K leads to the collapse of the infrared band assigned to linearly adsorbed NO to give a band centered at 1772 cm/sup -1/. This band is assigned to strong vibrationally coupled NO adsorbed on the smooth, more densely packed crystal planes of Pt. Pretreatment in O/sub 2/ at 673 K leads to the enhancement of the linearly adsorbed NO species, while pretreatment in H/sub 2/ promotes vibrationally coupled NO. These results are explained by considering surface reconstruction rather than by changes in Pt dispersion.

La reaction de CBr 4 avec CoW 12 O 40 7− , est du 1er ordre par rapport au substrat et au reactif, l'etape determinant la vitesse etant une reaction de transfert d'electron dans la sphere externe. Les seuls produits sont CHBr 3 et C 2 Br 6 . La reaction avec CoW 12 O 40 8− est du 1er ordre

Synthese des composes du titre par reaction de benzaldehydes avec des dianions issus de la lithiation de l'acide dimethoxy-2',6' phenoxyacetique

C 18 H 22 O 7 cristallise dans P1 avec affinement jusqu'a 0,052. C 18 H 20 O 7 •CH 3 OH cristallise dans Pca2 1 avec affinement jusqu'a 0,042

Synthese des composes du titre a partir d'aldehydes ou de cetones et de N-[bis-hydroxymethyl-1,1 ethyl] acetamide; etude RMN 13 C, 1 H et spectrometrie deux dimensions

The transformations (hydrogenolysis and isomerization) of stereo-isomeric α, α'-dimethyloxacycloalkanes ( 1–8 ) were studied on Pt and Ni catalysts. On Pt, the cis oxirane is transformed at a much higher rate than the trans isomer, whereas there is scarcely any difference between the isomers of the 4 - 6-membered cyclic ethers; nor was the difference in reaction rate on Ni very considerable for the oxiranes. The experimental results have led to new conclusions on the absorption of the oxacycloalkanes, the mechanism of their hydrogenolysis and the stereochemistry.

The major degradation product of desonide in a pharmaceutical ointment formulation has been shown to be identical with the C-17-carboxylic acid obtained on oxidative cleavage of the alpha-ketol group of desonide with alkaline hydrogen peroxide. The pKa value of this acid has been estimated from chromatographic data.