Isomeric Aldehydes Research Articles

ChemInform Abstract: Intramolecular Capture of Pummerer Rearrangement Intermediates. Part 3. An Interrupted Pummerer Reaction Induced by Vilsmeier Reagent (POCl3/ DMF).

AbstractVilsmeier‐Haack formylation of the fused benzothiazole (I) yields the isomeric aldehydes (III) and (IV).

ChemInform Abstract: Stereoselective Allylation for Preparation of L‐Hexose Derivatives.

AbstractThe isomeric aldehydes (III), prepared as described in the reaction scheme, are coupled with the allylic organometallic compounds (V) to give mixtures of the isomeric adducts (VI).

Biosynthetic relationship of citral- trans and citral- cis in cymbopogon flexuosus (lemongrass)

Use of [ 14C, 3H]-labelled precursors revealed that leaf blades of Cymbopogon flexuosus converted geraniol (3,7-dimethylocta- trans-2,6-diene-1-ol) into citral- trans with loss of pro-(1 S) hydrogen whereas nerol lost the pro-(1 R) hydrogen while being converted into citral- cis. Secondly, the citral- trans is converted into citral- cis and vice versa and there is no separate route for the biosynthesis of either of the two aldehyde isomers.

Condensed heterocycles. 42. Synthesis and some properties of 3-hydroselenobenzo[b]furan-2-carbaldehyde and 2-hydroselenobenzo[b]furan-3-carbaldehyde

The reactions of 3-chlorobenzo[b]furan-2-carbaldehyde and 2-bromobenzo[b]furan-3-carbaldehyde with sodium hydrogen selenide have yielded isomeric hydroseleno aldehydes which, under the action of atmospheric oxygen, have oxidized to diselenides, while alkylation of the seleno aldehydes with methyl iodide leads to the formation of the corresponding methylseleno derivatives.

Gibberelline-91: Detaillierter 1H-NMR-strukturbeweis von epimeren hydroxycyclobutanen, deren synthese durch photocyclisierung von diacetylgibberellin-A 3-7-aldehyd und basische rückspaltung

Photoceyclization of diacetylgibberellin-A3-7-aldehyde 1 leads to the epimeric hydroxycyclobutanes 2 and 3. The configurations at the new asymmetric centres at C-7 and C-15 of the four-membered ring have been determined by 1H-NMR (homonuclear decoupling and INDOR techniques). Retroaldol-like cleavage of 2 and 3 under mild alkaline conditions gives the starting aldehyde 1 and the Δ 15 -isomeric aldehyde 6. Oxidation and deacetylation of 6 afford 16,17-dihydro-15,16-dehydro-gibberellin-A 3 7.

Geometric specificity of alcohol dehydrogenases and its potential for separation of trans and cis isomers of unsaturated aldehydes.

The geometric specificity of three different alcohol dehydrogenases (alcohol:NAD+ oxidoreductase, EC 1.1.1.1) (from yeast, from horse liver, and from Leuconostoc mesenteroides) in the reduction of trans- and cis-cinnamaldehydes has been investigated. All three enzymes display a remarkable trans specificity: they react with the trans isomer 7 to 647 times faster than with its cis counterpart. Experiments with the enzymatic reduction of 3-phenylpropionaldehyde, a saturated analog of cinnamaldehyde, have revealed that whereas trans-cinnamaldehyde possesses the "right" configuration for the active centers of the alcohol dehydrogenases, the cis isomer apparently does not fit the active centers well. All three alcohol dehydrogenases studied also exhibit a marked trans specificity in the reaction with alpha-methylcinnamaldehyde. The geometric specificity of alcohol dehydrogenases can be used for the production of otherwise hard to synthesize cis isomers of unsaturated aldehydes from their readily available trans counterparts: trans-cinnamaldehyde was irradiated with ultraviolet light (which converted it to a mixture of trans and cis isomers) then treated with NADH and yeast alcohol dehydrogenase (which selectively reduces only trans aldehyde into the alcohol), and finally the mixture of cis-cinnamaldehyde and trans-cinnamyl alcohol was separated easily by preparative column chromatography.

Photochemische Reaktionen. 106. Mitteilung. Zur Photochemie tetraalkylsubstituierter γ‐Keto‐olefine

The Photochemistry of Tetraalkyl Substituted γ‐Keto‐olefinesThe photochemistry of 7,8‐dihydro‐β‐ionone (1) in solution is shown to depend on temperature, polarity and viscosity of the solvent. UV. irradiation (λ ≥ 245 nm) in pentane at +25° converts 1 to the isomeric ethers 3 (16%), 5A (48%) and 5B (22%), whereas at −65° 7,8‐dihydro‐γ‐ionone (26) is obtained in 12% yield together with 13% of 3, 12% of 5A and 9% of 5B. The 1n,π*‐excitation of 1 in acetonitrile gives similar results. In the more viscous 1,2,3‐triacetoxypropane the photoisomerization 1 → 26 takes place even at + 60° (10% yield, cf. 40% at −15°). In alcoholic solvents, however, no formation of 26 is detected, but the hitherto unknown [2+2]‐photocycloaddition 1 → 11 can be observed (4% at −7°, 15% at −65S° in 2‐propanol). An intermediate e may be involved (Scheme 14). In addition to the photoreactions 1 → 3, 5A, 5B and 11 the isomerization of 1 to the novel spirocyclic ketone 28 takes place in alcoholic solvents only.Photoisomerization 1 → 3 is presumably a photo‐ene process involving a stereoselective intramolecular H‐transfer. This type of photoisomerization is restricted to cyclic γ‐keto‐olefines. The tetraalkylated acyclic γ‐keto‐olefines 14 and 15 photoisomerize exclusively by [2+2]‐cycloaddition, independent of the solvent.On 1n,π*‐excitation the δ,ϵ‐unsaturated bicyclic ketone 44 undergoes Norrish‐Type‐II photofragmentation to the diene 45 or isomerizes to the γ, ϵ‐unsaturated ketone 17. Competition between these two reactions is strongly temperature dependent: photolysis in pentane at −72° yields quantitatively 45, whereas at + 35° only 30% of 45 and 68% of 17 are obtained.UV. irradiation of the novel spirocyclic ketone 28 gives as primary photoproduct the isomeric aldehyde 29, and in a secondary photoreaction the isomeric oxetanes 30A and 30B. Experiments with deuteriated substrates show that the isomerization of type 28 → 29 is stereocontrolled.

Acute and cutaneous toxicity of beta-chlorovinyl ketones and aldehydes in rodents.

The acute toxicity (LD50, intraperitoneal in the mouse) of beta-chlorovinyl ketones and aldehydes used as intermediates for organic syntheses was determined and their action on the skin of rodents investigated. Ketones of the type Cl-CH-CH-COR prove to be relatively toxic and display a markedly necrotic action after percutaneous absorption. In comparison with this the isomeric aldehydes Cl-CR-CH-CHO have a lower acute and less markedly cutaneous toxicity. As therapeutic counter action after skin contamination by beta-chlorovinyl carbonyl compounds the immediate treatment with an aqueous ethanolic solution of hexamethylenetetramine is recommendable.

Catalysis by supported metal crystallites prepared from metal carbonyl clusters: III. Catalytic vapor-phase hydroformylation of olefins over Rh, bimetallic RhCo, and Co crystallites prepared from the carbonyl cluster compounds dispersed on zinc oxide

The carbonyl clusters Rh/sub 4/(CO)/sub 12/, Rh/sub 6/(CO)/sub 16/, RhCo/sub 2/(CO)/sub 12/, RhCo/sub 3/(CO)/sub 12/, and Co/sub 4/(CO)/sub 12/ were deposited on ZnO and activated by pyrolysis (vacuum, 130/sup 0/-145/sup 0/C) or by activation above 90/sup 0/C in ethylene (or propylene), hydrogen, and carbon monoxide mixtures. The method of activation had no effect on the hydroformylation activity or selectivity. The specific rate for hydroformylation of ethylene or propylene to propanol and butyraldehyde, respectively, was 1.5-2.8 times higher on the rhodium derived from Rh/sub 4/(CO)/sub 12/ than on the rhodium derived from Rh/sub 6/(CO)/sub 16/, but the selectivity for the normal aldehyde isomer was higher on the latter catalyst. Relative rates for propylene hydroformylation depended on the catalyst precursor as follows: 100 for Rh/sub 4/(CO)/sub 12/, 60 for Rh/sub 2/Co/sub 2/(CO)/sub 12/, 42 for RhCO/sub 3/(CO)/sub 12/, and 5.2 for Co/sub 4/(CO)/sub 12/. IR spectroscopy suggested that the active species is a rhodium cluster carbonyl formed in situ from the metal crystallites formed upon activation; the role of cobalt in the bimetallic crystallites is apparently to act as electron donor to rhodium.

Asymmetric Hydroformylation of α‐[2H]‐Styrene. Preliminary Communication

AbstractThe hydroformylation of α‐[2H]‐styrene in the presence of an asymmetric rhodium‐catalyst afforded two optically active isomeric aldehydes. The origin of the asymmetric induction is discussed on the basis of the chirality and the optical purity of the two products.

Silver Nitrate-High Pressure Liquid Chromatography of Geometrical Isomers

Rapid, highly efficient preparative liquid chromatographic separations of geometrical isomers of unsaturated acetates, aldehydes, and hydrocarbons were obtained with silver nitrate coated on silica gel. When benzene was used, the compounds eluted in a reasonable time and the columns could be reused since they showed no significant deterioration. Silica gel of three ranges of partical size treated with AgN03 in our laboratory produced lower operating pressures and better peak shape than commercially obtained AgN03-silica.

Synthèse de la cyclonéolitsine

Cycloartenol epoxide has been isomerised by stannic chloride to the 24-ketone and an isomeric aldehyde. This aldehyde has been converted to cycloneolitsin, a naturally occurring 24,24-dimethylated triterpene.

Reactions of Potassium Iron Carbonylate with Olefins and Alkyl Halides

Abstract Potassium iron carbonylate, KHFe(CO)4, reacted with ethyl acrylate, crotonate, 3-butenoate, styrene, and α-olefins at 40–70°C under an atmosphere of carbon monoxide. Methylmalonate was selectively obtained from the acrylate by treatment of the reaction mixture with an alcoholic iodine and hydrogen chloride solutions. Dipotassium iron carbonylate, K2Fe(CO)4, reacted with β-bromopropionate to give mainly methylmalonate. Isomerization of β-ethoxycarbonylpropionyliron carbonylate to the α-isomer occurred readily in contrast to isomerization of acylcobalt carbonyl. Both crotonate and 3-butenoate gave ethylmalonate as a major product and methylsuccinate and glutarate as minor ones. The results suggest that α-ethoxycarbonylbutyliron carbonylate is more predominant than the corresponding β- and γ-isomers in equilibrium state. This is in striking contrast to the case of acylcobalt carbonyl. Styrene yielded two isomeric aldehydes, α- and β-phenylpropionaldehydes. Ethyl caproate and enanthate were obtained from 1-pentene and 1-hexene, respectively in poor yield.

Separation of positional and geometrical isomers of monoenoic aldehydes via the dinitrophenylhydrazones

Separation of positional and geometrical isomers of monoenoic aldehydes via the dinitrophenylhydrazones

The cardiac glycosides of Gomphocarpusf ruticosus R.Br. I. Afroside

Afroside, C29H42O9, is a new cardiac glycoside which has been obtained from Gomphocarpus fruticosus R.Br. It contains a carbonyl (aldehyde) group at C10, and a secondary hydroxyl group in the nucleus, which has been placed provisionally at position C11. On the basis of the available evidence, afroside appears to consist of a mixture of the isomeric free aldehyde and the 19-11 cyclic hemiacetal forms. Of these substances, the cyclic hemiacetal form is the only one which has been isolated in pure condition (afroside B). Acetylation of afroside produced a triacetate, C35H46O12.H2O, which is identical with that obtained by the acetylation of afroside B. Reduction of afroside with sodium borohydride produces afrosidol, C29H44O9, which shows no evidence for a carbonyl group at C10. Hydrolysis of afroside produces α-anhydroafrogenin, C23H28-30O5.H2O, which forms a monoacetate, C25H32O7.H2O. The infra-red spectra of these compounds show the presence of a saturated γ-lactone ring in the structure of the nucleus, besides the normal Δα-β-γ-lactone ring at C17 (1786, 1755, 1633 cm-1). Acetyl-α-anhydroafrogenin also shows an intense absorption band of simple structure at 1238 cm-1, which indicates an equatorially orientated acetyl group at C3. As all the naturally occurring cardiac aglycones of known structure have a β-orientated hydroxyl group at C3, for the substituent in this position to be equatorial, the A/B ring junction is probably trans. Hydrolysis of afrosidol produces α-anhydroafrogenol, C23H32O5.H2O, which forms a diacetate, C27H36O7.H2O. The infra-red spectrum of α-anhydroafrogenol shows no evidence of the saturated y-lactone ring which is present in the structure of α-anhydroafrogenin.

Synthéses dans le domaine des hydrocarbures cancérigènes — XIV Dérivés méthylés du pyréne

AbstractSeveral new polymethylpyrenes have been synthesised in order to test them for possible carcinogenic activity. Formylation of 3‐methylpyrene (german nomenclature) gives a complex mixture of aldehydes from which 3‐methyl‐5‐formylpyrene (m.p.: 102‐103°) has been isolated.It has been shown that 3‐methyl‐10‐formylpyrene is also present in the reaction mixture.Reduction (Huang‐Minlon) of the formyl derivatives affords 3,5‐dimethylpyrene (m.p.: 98‐99°) and 3,10‐dimethylpyrene (m.p.: 129‐130°) respectively.Treatment of 3,8‐dibromopyrene with butyl‐lithium followed by methyl sulfate gives the isomeric 3,8‐dimethylpyrene (m.p.: 165‐166°).3,5‐Dimethyl‐8‐formylpyrene (m.p.: 171‐172°), 3,8‐dimethyl‐5‐formylpyrene (m.p.: 187°) and 3,10‐dimethyl‐5‐formylpyrene (m.p.: 175‐176°) are obtained by formylation of the above corresponding dimethylpyrenes.These isomeric aldehydes all give 3,5,8‐trimethylpyrene (m.p.: 178‐179°) on reduction. Further formylation and reduction affords 3,5,8‐trimethyl‐10‐formylpyrene (m.p.: 275‐276°) and 3,5,8,10‐tetramethylpyrene (m.p.: 269‐270°).Formylation of 4‐methylpyrene (new preparation given) followed by reduction gives a dimethylpyrene (m.p.: 62°) different from 3,4‐dimethylpyrene (m.p.: 104‐105°) and which, therefore, probably is the 4,8‐dimethylpyrene. The intermediate 4‐methyl‐8‐formylpyrene (m.p.: 93‐94°) was isolated.U. V. Spectra of the new polymethylpyrenes are given.

Production of ammonium nitrate by continous vacuum crystallisation

Une synthèse de la cyclonéolitsine est réalisée à partir de l'époxyde-24,25 du cycloarténol.Cycloartenol epoxide has been isomerised by stannic chloride to the 24-ketone and an isomeric aldehyde. This aldehyde has been converted to cycloneolitsin, a naturally occurring 24,24-dimethylated triterpene.

Studies in p-Cymene. II.1 The Isomeric Aldehydes Derived from p-Cymene

Studies in <i>p</i>-Cymene. II.¹ The Isomeric Aldehydes Derived from <i>p</i>-Cymene