Facile photochemical transformation of alkyl aryl selenides to the corresponding carbonyl compounds by molecular oxygen: use of selenides as masked carbonyl groups

Alkyl aryl selenides with and without functional groups on the alkyl group were transformed efficiently into the corresponding carbonyl compounds, particularly primary alkyl aryl selenides in good yields, by a simple photolysis in the presence of air or oxygen. This transformation can be conducted without protection of functional groups. The yield of carbonyl compounds was much affected by the solvent viscosity, reaction temperature, concentration of dissolved oxygen in the solvents, wavelength of light, and structure of the aryl substituents. The present study indicates that aryl selenides can be considered as a masked carbonyl group that can be easily converted to a carbonyl group by very mild reaction conditions even in the presence of various unprotected functional groups. Therefore, this functional group transformation can be used as an important tool in organic synthesis due to its simplicity and mild reaction condition.     

Iron-mediated electrochemical reaction of alpha-chloroesters with carbonyl compounds

[reaction: see text] Reformatsky-type reactions have been performed efficiently using an electroassisted iron-complex catalysis. Valuable product such as beta-hydroxyesters, ketones or nitriles are thus prepared with high yields.     

Rhenium-catalyzed reaction of carbonyl compounds with ketene silyl acetals

It was found that rhenium complex is an effective catalyst for the reaction of carbonyl compounds with ketene silyl acetals. A wide range of β-silyloxy esters is obtained by the treatment of carbonyl compounds with ketene silyl acetals in the presence of a catalytic amount of ReBr(CO)₅ in moderate to good yields.     

Photoreactions of benzosilacyclobutenes with carbonyl compounds. SH2 reaction on SiC bond by triplet carbonyl compounds

Photoreaction of 2,3-benzo-1,1-diphenyl(or dimethyl)-1-sila-2-cyclobutene with an aldehyde or ketone results in 1:1 cycloadduct of [4+2] type, the formation of which is accountd for in terms of S_H2 process, i.e., attack of a triplet carbonyl compound on the silicon of the benzosilacyclobutene.     

Variation of pH in reaction of sodium sulfide with carbonyl compounds

The results of an experimental study of how pH varies in the course of a reaction between sodium sulfite and carbonyl compounds are presented.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 12, 2004, pp. 2031–2035.Original Russian Text Copyright © 2004 by A. Ivanov, Altukhova, I. Ivanov.     

Reactivity of stable trifluoroacetaldehyde hemiaminals. 1. An unexpected reaction with enolizable carbonyl compounds.

In the presence of enolizable carbonyl compounds, hemiaminals of fluoral and related polyfluoroaldehydes behave as equivalents of fluoroalkyl iminium compounds and provide beta-polyfluoroalkyl beta-dialkylamino ketones, which are easily transformed, under acidic conditions, into beta-polyfluoroalkylenones.     

α-Carboxylation reaction of carbonyl compounds with bromomagnesium ureide-carbon dioxide adducts

Bromomagnesium ureide-carbon dioxide adducts, models of the carboxylated biotin complex, undergo caboxylation of a variety of carbonyl compounds in good yield.     

Unusual reaction of beta-hydroxy alpha-diazo carbonyl compounds with Cl3CCN/NaH and Rh(II)-catalyzed reaction of beta-trichloroacetylamino alpha-diazo carbonyl compounds

The hydroxyl group was directly converted into the trichloroacetylamino group by reacting beta-hydroxy alpha-diazo carbonyl compounds with Cl(3)CCN and NaH. Rh(II)-catalyzed reactions of the beta-amino alpha-diazo carbonyl compounds were discussed. [reaction: see text]     

Catalytic olefination of carbonyl compounds. Effect of the structure of the carbonyl compound on the reaction

The mechanism of the novel reaction of catalytic olefination of carbonyl compounds was studied. The reaction involves the transformation of hydrazones of aromatic aldehydes and ketones into the corresponding dichloroalkenes and symmetrical azines by the treatment with carbon tetrachloride in the presence of CuCl as a catalyst. The stability of intermediate diazoalkanes is the main factor determining the direction of the reaction. In the case of sufficiently stable diazoalkanes, other products can be formed under the reaction conditions along with the products of catalytic olefination.     

Structure of products of the reaction of 2-cyanoaziridine with carbonyl compounds

The structure of azimexone (3), the product of the reaction of 2-cyanoaziridine with acetone, was confirmed on the basis of¹H and¹³C NMR spectra. The formation of this product is accounted for by the -aziridinoalkylating action of an intermediate containing a good leaving iminoyloxy group. Similar reactions were observed for 1-chloromethylaziridine and a 1-aziridinylmethylammonium salt (6), but not for 1-methoxymethylaziridine (7) and 1-aziridinemethanol.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2136–2139, December, 1993.     

Electrochemically induced Henry reaction of nitromethane and carbonyl compounds

The electrolysis of carbonyl compounds and nitromethane in methanol or in the mixture of methanol and DMF in an undivided cell results in the formation of corresponding β-nitroalcohols in 60-75% yields. Thus, the simple electrocatalytic system can produce under mild conditions an electrochemically induced Henry reaction.     

Differences among the mechanisms of reaction of phenylhydroxylamine with various carbonyl compounds

In order to obtain a better knowledge of the special behavior of phenylhydroxylamine as a nucleophile, the mechanism of its reaction with 2,6‐dichlorobenzaldehyde, norcamphor, and cyclohexanone, and also the hydrophobic effect on its reaction with 2,6‐dichlorobenzaldehyde and benzaldehyde, was studied. The results led us to assume that the planar molecule of phenylhydroxylamine should be placed parallel to the planar molecule of benzaldehyde in order to permit the attack of the lone electron pair of the nitrogen on the carbonyl group, forming, together with a hydrogen bond between the hydroxyl group and the carbonylic oxygen atom, a packed preassociation complex. This mechanism is not observed in the case of norcamphor or 2,6‐dichlorobenzaldehyde due to the steric hindrances produced by the lack of planarity of these molecules. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 453–459, 2000     

二茂镁的原位合成及其与羰基化合物的反应

研究了通过萘锂还原法制得的活性镁与环戊二烯原位合成环戊二烯基镁(Cp~2Mg)的方法。Cp~2Mg的存在是由它与醛酮反应生成富烯得到证实。此法产率高, 方法简单, 条件温和。     

Regioselective synthesis of linalyl compounds via addition reaction of geranyl bromide and tin with carbonyl compounds

Linalyl alkyl or aryl carbinols were regioselectively synthesized by the reaction ofgeranyl bromide and powdered tin with aldehydes and ketones.     

Intermediates in the reaction ofo-phenylenediamine with carbonyl compounds and their subsequent conversions

The reaction ofo-phenylenediamine with aldehydes and ketones has been studied using PMR spectroscopy. It has been established that the reaction begins with the formation of monoimines (isolated in condensations with aromatic aldehydes) which are cyclized to the corresponding benzimidazolines. The latter are converted in the reactions involving aldehydes and pinacolone into 2-substituted benzimidazoles, but with acetone and acetophenone give 2,3-dihydro-1H-benzo[b]-1,4-diazepine derivatives.Academy of Military Medicine, Saint Petersburg 194175, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 363–367, March, 1998.     

The reaction pattern of norbornene with excited state carbonyl compounds: Photochemical preparations of norbornene derivatives

We established that acetylacetone and acetone photolytically sensitize norbornene to undergo an efficient radical addition of solvent (ranging from hexane, cyclic ethers, haloalkanes, acetone, alcohols and acetonitrile) across the double bond. In view of its synthetic applicability, sensitized photoreactions of norbornene were reviewed and their mechanisms were compared. Photolysis of acetylacetone in the presence of norbornene in hexane induced i) acetylacetone to cycloadd to norbornene giving the expected 1,5-diketone, and ii) sensitization by triplet excited acetylacetone to generate reactive norbornene, which underwent dimerization as well as the addition of a solvent molecule by radical chain processes. In other solvents, the radical chain addition of solvent dominated the photoreaction, and superseded the cycloaddition, to give excellent to good yields of adducts to norbornene. While the excited species of acetylacetone for the sensitization was deduced to be its spectroscopic triplet excited state, that for the cycloaddition should involve a different one which may be a twisted triplet acetylacetone; sensitization experiments showed that the cycloaddition did not occur from the spectroscopic triplet state. Triplet excited acetone sensitized norbornene to undergo the same solvent addition more efficiently and cleanly than acetylacetone did. In view of various conflicts existing in the proposed energy transfer mechanism, the sensitized norbornene reactions were rationalized with electron transfer and a cation radical chain mechanism.