Reaction of acetylenic ketones with hydrazine derivatives. Synthesis of hydroxypyrazoles

Aroylphenylacetylenes Ia-c react with (-butyl hydrazinecarboxylate (IIa) and 2-furylhydrazide (IIb) to give the corresponding hydroxydihydropyrazole derivatives IVa-f. This cyclic structure is supported by chemical transformations. Thus, when compounds IVa-c are heated with acetic anhydride, they yield the corresponding 5-aryl-1-(t-butoxycarbonyl)-3-phenylpyrazoles Va-c which, upon hydrolysis with methanolic potassium hydroxide, produce the corresponding 5(3)aryl-3(5)phenylpyrazoles VI. Spectroscopic data also confirm the suggested cyclic structure IV.     

Synthesis of fluorous acetal derivatives of aldehydes and ketones

The formation of acetals (and ketals) from polyfluoroalkylated 1,3-alkanediols and aldehydes and ketones is demonstrated for the first time. Four sets of reaction conditions are examined and the degree of conversion is shown to depend upon reaction conditions and the structure of the carbonyl substrate. Excellent yields are obtained, and wherever possible, diastereomeric products are observed.     

Catalytic hydroboration of aldehydes and ketones with sodium hydride: Application to chemoselective reduction of aldehydes over ketones

Sodium hydride-promoted catalytic hydroboration of aldehydes and ketones with pinacolborane (HBpin) was examined, and 10?mol% of NaH was found to cause the HBpin to participate in hydroboration in a convenient and efficient manner at mild reaction conditions. Further chemoselective hydroboration of aldehyde over ketone functionality was also analyzed. In addition, no hydroboration was observed form ester, acyl chloride, amide, nitrile, alkene, alkyne, alkyl halide and epoxide functional groups indicate that present system (HBpin, NaH) is highly selective for aldehydes and ketones.     

Solvent-free reduction of aldehydes and ketones using solid acid-activated sodium borohydride

A simple and convenient procedure for the reduction of aldehydes and ketones with sodium borohydride activated by solid acids such as boric acid, benzoic acid, and p-toluenesulfonic acid monohydrate under solvent-free conditions is described.     

Reaction of tetracyanocyclopropyl ketones with hydrazine hydrate

The reaction of 2,2,3,3-tetracyanocyclopropyl ketones with hydrazine involved the addition at the carbonyl and cyano groups and resulted in the formation of previously unknown polycyclic systems whose common feature was the presence in the structure of a pyridazine ring. In the general case 3-substituted 6-amino-8-oxo-4,5,7-tptriazatricyclo[4.3.0.0^2.9]-non-3-ene-1,9-dicarbonitriles were obtained. The reaction with 3-pivaloylcyclopropane-1,1,2,2-tetracarbonitrile took another route with the opening of the three-membered ring and the formation of 3-amino-7a-tert-butyl-6-oxo-5,6,7,7a-tetrahydro-4aH-pyrrolo[2,3-c]pyridazine-4,5-dicarbonitrile.     

Determination of traces of aldehydes and ketones in the troposphere via solid phase derivatisation with DNSH

Summary A method for the determination of aldehydes and ketones based on simultaneous collection and derivatisation of the compounds on a solid phase is described. This kind of derivatisation is highly efficient and can be used with a flow rate of 2 l/min. Reaction of the substances with dansylhydrazine (DNSH) leads to hydrazones. In the following step the solution is concentrated to a volume of 200 l, separation is made by RP-HPLC, detection via fluorescence. Because aldehydes and ketones show different reactivities on the solid phase the described method is an elegant possibility to discriminate these two classes of organic compounds.

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Bestimmung von Aldehyd- und Ketonspuren in der TroposphÄre durch Festphasenderivatisierung mit DNSH

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Note of thanks. We thank DFG (SFB 233) for financial support.     

Condensation of aldehydes and ketones

The Mannich reaction with methylene- and benzylidenediacetophenones has given: 1,3-dibenzoyl-4-piperidinobutane, 1,3-dibenzoyl-4-morpholinobutane, 1,3-dibenzoyl-4-diethylamino-2-phenylbutane, 1,3-dibenzoyl-2-phenyl-4-piperidinobutane, 1,3-dibenzoyl-4-diethylaminobutane, and 1,3-dibenzoyl-4-dimethylamino-2-phenylbutane. From the latter two compounds, 3-diethylaminomethyl-2,6-diphenylpyridine and 3-dimethylaminomethyl-2,4,6-triphenylpyridine have been obtained.For part XVII, see [7].     

Synthesis, spectral and solid state characterization of a new bioactive hydrazine bridged cyclic diphosphonium compound

The facile preparation of a racemic hydrazine bridged diphosphonium compound possessing a ring system analogous to bicyclo[3.3.2]decane is reported. Although the reaction yield is low, the structure of the compound, which possesses an eight-membered ring, two phosphonium cationic centers, a biimino bridge, molecular chirality and two fused aromatic rings locked into roughly perpendicular planes is unusual. The compound displays substantial biological activity in the brine shrimp test and cleaves plasmid DNA.     

Condensation of aldehydes and ketones

The alkaline condensation of -aceto-and -propionaphthalenes with furfural has given, respectively, 2-(-furfuryl)-1, 3-di(-naphthoyl)-propane and 3-(-furyl)-2,4-di(-naphthoyl)pentane; both -diketones have also been obtained by the Michael condensation. Under more severe conditions, two molecules of furfural condense with three molecules of -acetonaphthalene to form 2, 4-di(-furyl)-1, 3, 5-tri(-naphthoyl)pentane. Under similar conditions, benzaldehyde exhibits only a feeble capacity for triketone condensation with -acetonaphthalene. The condensation of -propionaphthalene with furfural has given the new compound furylidenepropionaphthalene. It has been shown that both under the conditions of the improved Chichibabin pyridine synthesis and under the conditions of the Leuckhardt reaction, 3-(-furyl)-1, 3-di(-naphthoyl)propane gives 4-(-furyl)-2, 6-di(-naphthyl)pyridine.     

Synthetic talc as a solid base catalyst for condensation of aldehydes and ketones

Magnesium organo silicates (MOSs; synthetic talc) as such and with amine surface functionalities were synthesized by sol–gel method under non-hydrothermal conditions and characterized by spectroscopic techniques. The synthesized talc samples were observed to be thermally stable up to 200 °C in nitrogen atmosphere and used as catalysts for condensation of aldehydes and ketones. Application of synthetic talc as a solid base catalyst for condensation of aldehydes and ketones is being reported for the first time. The effect of solvent, solvent to reactant molar ratio, amount of catalyst and temperature was studied in detail for self-condensation of propanal. High conversion (86%) of propanal with 95% selectivity of 2-methylpentenal was achieved using dimethyl sulphoxide as a solvent. The kinetic study was carried out for the condensation of propanal catalyzed by amine functionalized MOS under optimum reaction conditions. Catalyst was re-used without significant loss in activity up to three cycles.     

Condensation of aldehydes and ketones

The alkaline condensation of β-aceto-and β-propionaphthalenes with furfural has given, respectively, 2-(α-furfuryl)-1, 3-di(β-naphthoyl)-propane and 3-(α-furyl)-2,4-di(β-naphthoyl)pentane; both δ-diketones have also been obtained by the Michael condensation. Under more severe conditions, two molecules of furfural condense with three molecules of β-acetonaphthalene to form 2, 4-di(α-furyl)-1, 3, 5-tri(β-naphthoyl)pentane. Under similar conditions, benzaldehyde exhibits only a feeble capacity for triketone condensation with β-acetonaphthalene. The condensation of β-propionaphthalene with furfural has given the new compound furylidenepropionaphthalene. It has been shown that both under the conditions of the improved Chichibabin pyridine synthesis and under the conditions of the Leuckhardt reaction, 3-(α-furyl)-1, 3-di(β-naphthoyl)propane gives 4-(α-furyl)-2, 6-di(β-naphthyl)pyridine.     

Electroreductive crossed pinacol coupling of aromatic ketones with aliphatic ketones and aldehydes

The intermolecular crossed pinacol coupling of aromatic ketones with aliphatic aldehydes and ketones was effected by electroreduction in the presence of chlorotrimethylsilane. The best result was obtained using a Pb cathode in Bu₄NPF₆/THF. The electroreduction of aromatic 1,4-, 1,5-, and 1,6-diketones under the same conditions gave four-, five-, and six-membered 1,2-diols with trans-stereoselectivity, while the reduction of these diketones with TiCl₄-Zn produced the cis-isomers of the same intramolecular crossed pinacol coupling products predominantly.     

Reduction of aldehydes and ketones with tetraalkylammonium borohydrides

Misinterpretations regarding the selectivity of tetraalkylaminonium borohydride reductions in dichloromethane are resolved. Tetrabutyl ammonium borohydride offers several advantages, but both it and tetraethyl ammoniumborohydride are highly useful synthetic reagents.     

Reactions of diorganoytterbium compounds with ketones and aldehydes

Reactions of the diorganolanthanoids R₂Yb (R = PhCC or C₆F₅) with aldehydes (R′CHO) and ketones (R′₂CO) (R = Me or Ph) followed by hydrolysis generally gives the alcohols RR′CH(OH) or RR′₂COH, but, with benzophenone, reduction giving benzopinacol either competes (R = PhCC) or is predominant (R = C₆F₅).