Mild and direct conversion of esters to morpholine amides using diisobutyl(morpholino)aluminum: application to efficient one-pot synthesis of ketones and aldehydes from esters

Morpholine amide intermediates, which are easily prepared by aminolysis of various esters with diisobutyl(morpholino)aluminum, react with organolithium and reducing agents (DIBALH or LDBMA) without isolation of the aminolysis intermediates to give ketones in 83–95% yields and aldehydes quantitatively.     

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.     

Synthesis of sterically hindered enamides via a Ti-mediated condensation of amides with aldehydes and ketones

The first TiCl(4)-mediated condensation of secondary amides with aldehydes and ketones has been achieved. The reaction proceeds at room temperature and is complete within 5 h in most cases. The optimized procedure used 5 equiv of an amine base hinting that the in situ activation of both the amide and the Lewis acid is required. The reaction affords polysubstituted (E)-enamides.     

A novel reduction reaction for the conversion of aldehydes, ketones and primary, secondary and tertiary alcohols into their corresponding alkanes

A novel one-pot reaction has been developed for the reduction of aldehydes, ketones and primary, secondary and tertiary alcohols into their corresponding alkyl function. This is also the first reported method which can efficiently reduce primary, secondary, or tertiary alcohols, without affecting carbon-carbon double bonds, into their corresponding alkyl function in high yields. The reduction utilises either diethylsilane or n-butylsilane as the reducing agent in the presence of the Lewis acid catalyst tris(pentafluorophenyl)borane.     

Magnesium-oppenauer oxidation of alcohols to aldehydes and ketones

Using a magnesium-Oppenauer oxidation aldehydes and ketones are prepared from halomagnesium alkoxides, which in turn are the products of Grignard reactions.     

Iodine as a chemoselective reoxidant of TEMPO: application to the oxidation of alcohols to aldehydes and ketones

[reaction: see text] Chemoselective alcohol oxidations using catalytic TEMPO and stoichiometric iodine as the terminal oxidant were studied. Iodine was compared to other positive halogens as the terminal oxidant and shown to be superior in cases of electron-rich and heteroaromatic rings. The new conditions were successfully applied to an important intermediate (2) in the synthesis of Losartan.     

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].     

Sequential reactions promoted by manganese: completely stereoselective synthesis of (E)-alpha,beta-unsaturated amides, ketones, aldehydes, and carboxylic acids

A complete E-selective synthesis of alpha,beta-unsaturated amides through a sequential reaction of a range of dichloroamides with a variety of aldehydes promoted by Rieke manganese (Mn*) is reported. A mechanism based on a sequential aldol-type reaction and a completely stereoselective beta-elimination is proposed to explain these results. The unsaturated amides obtained are readily and efficiently transformed into alpha,beta-unsaturated ketones, aldehydes, or carboxylic acids without loss of the diastereoisomeric purity of the C-C double bond.     

Fluoride-catalyzed conversion of acylsilanes to aldehydes and ketones

Acylsilanes undergo efficient protodesilylation upon treatment with fluoride ion in moist DMSO, HMPT, or THF. The reaction is also catalyzed by methoxide ion in methanol or DMSO, but not by chloride ion or bromide ion. Fluoride-catalyzed desilylation in the presence of alkyl halides, aldehydes, or ketones results in modest yields of the corresponding alkylated products.     

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.     

Transition metal-catalyzed conversion of aldehydes to ketones

Ketones are one of the most important classes of organic compounds, and widely present in various pharmacological compounds, biologically active molecules and functional materials. Over the past few decades, transition metal-catalyzed conversion of aldehydes has been found to be a powerful method. With the continuous development in recent years, it has become an efficient and uncomplicated strategy for constructing ketones. There are four major mechanisms for transition metal-catalyzed ketone synthesis from aldehyde: (1) carbonyl-Heck reaction, that is 1,2-insertion of organometal species to aldehydic C=O double bond, (2) direct insertion of transition metal catalysts to aldehydic C-H bond, (3) aldehyde as acyl radical, (4) aldehyde as carbon radical acceptor. This article summarizes related reports on the transformations of aldehydes to generate corresponding ketones under different reaction conditions.     

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.     

Tetrabutylammonium fluoride (TBAF)-catalyzed addition of substituted trialkylsilylalkynes to aldehydes, ketones, and trifluoromethyl ketones

Herein we report that tetrabutylammonium fluoride (TBAF) is a very efficient catalyst for the addition of trialkylsilylalkynes to aldehydes, ketones, and trifluoromethyl ketones in THF solvent at room temperature. The reaction conditions are mild and operationally simple, and a variety of aryl functional groups, such as chloro, trifluoromethyl, bromo, and fluoro groups, are tolerated. Impressively, using our protocol, useful CF(3)-bearing tertiary propargylic alcohols can be synthesized. Product yields are generally better than or comparable to those in the literature. 1-Phenyl-2-trimethylsilyl acetylene, trimethyl ((4-(trifluoromethyl)phenyl)ethynyl)silane, 1-trimethylsilyl-1-hexyne, and trimethyl(thiophen-3-ylethynyl)silane underwent clean conversion to their corresponding propargylic alcohols as products under our conditions. Heterocyclic carbonyl compounds, such as furan-3-carboxaldehyde, thiophene-3-carboxaldehyde, and 2-pyridyl ketone, gave good yields of propargylic alcohols.     

Enthalpies of addition of radicals to aldehydes, ketones, acids and esters

Enthalpies of the addition of radicals HO^•, HO₂ ^•, CH₃ ^•, CH₃O^•, CH₃O₂ ^• to the C=0 bond of model aldehydes, ketones, acids and esters have been calculated by thermodynamic and quantum chemical methods. It has been shown that the exothermic effect of these reactions decreases in the row HO^•>CH₃O^•>CH₃ ^•>HOO^•>CH₃OO^•.     

a-Hydroxy amides from carbamoylsilane and aldehydes

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