Reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds

The reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds give 1,2,4-triazepino [2,3-a]benzimidazole and pyrimido [1,2-a]benzimidazole-derivatives.     

Adamantylation of β-dicarbonyl compounds

Reactions of adamantan-1-ol with β-dicarbonyl compounds in 1,2-dichloroethane in the presence of In(OTf)₃, Ga(OTf)₃, Sc(OTf)₃, or Cu(OTf)₂ give the corresponding adamantylated derivatives in 45–93% yields.     

Reactions of (arene)tricarbonylchromium stabilized carbocations with aromatics and β-dicarbonyl compounds

Primary and secondary benzylic carbocations, stabilized by a tricarbonyl-chromium group, gave coupling products with several aromatics or β-dicarbonyl compounds in good yield and this reaction presents a new synthetic method for carbon-carbon bond formation. The chromium complexes of tertiary benzyl alcohols gave dehydrated products without carbon-carbon coupling products under similar conditions.     

Reaction of 8-chloro-5,7-dinitroquinoline with β-dicarbonyl compounds

3-(5,7-Dinitroquinolin-8-yl)pentane-2,4-dione, 5-(5,7-dinitroquinolin-8-yl)pyrimidine-2,4,6-trione, and 5-(5,7-dinitroquinolin-8-yl)-2,2-dimethyl-1,3-dioxane-4,6-dione cesium salts have been synthesized by a simple and efficient procedure via C-arylation of the corresponding β-dicarbonyl compounds with 8-chloro-5,7-dinitroquinoline.     

Interaction of aminals of conjugated ω-dimethylaminoaldehydes with cyclic β-dicarbonyl compounds

Reactions of aminals of conjugated -dimethylaminoaldehydes with Meldrum's acid,N,N-(o-phenylene)malonamides, and 2,3-dihydrophenalene-1,3-dione afford -dimethylaminodienones, substituted 2-dimethylamino-2H-pyrans, or oxanine salts. Cation-anionic polymethine dyes have been obtained from the latter.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 285–288, February, 1994.     

Reactions of aminoguanidine with α-dicarbonyl compounds studied by electrospray ionization mass spectrometry

Aminoguanidine possesses extensive pharmacological properties. This drug is recognized as a powerful α-dicarbonyl scavenger. In order to better elucidate the reactivity of aminoguanidine with α-dicarbonyls, aminoguanidine was reacted with several aldehydic and diketonic α-dicarbonyls. Electrospray ionization mass spectrometry is a suitable technique to study chemical and biochemical processes, and was selected for the purpose. In aminoguanidine reactions, triazines were detected and, other compounds that have never been reported before were identified. Triazine precursor forms were detected, namely tetrahydrotriazines and singly dehydrated tetrahydrotriazines. Moreover, species with bicyclic ring structures, and dehydrated forms, were also identified in aminoguanidine reactions. These species appear to result from tetrahydrotriazines and triazines reactions with one dicarbonyl molecule. Experiments revealed that these bicyclic species, in particular the ones resulting from triazines reactivity, could exist in solution, since they were both identified in the reactions of aminoguanidine and of a selected triazine with the dicarbonyls studied. The results obtained, regarding aminoguanidine/triazines reactivities, appear to support the capability of triazines to condensate and form polycyclic ring structures, and also to support literature mechanistic data for dihydroimidazotriazines formation via dihydroxyimidazolidine-triazines. The data obtained in this study may prove to be valuable to complement solution information, concerning the reactivity of amines with α-dicarbonyls, in particular.     

A study of the tautomerism of β-dicarbonyl compounds with special emphasis on curcuminoids

Six β-diketones related to curcumin and curcumin itself have been studied by ¹³C NMR spectroscopy in chloroform in order to determine the equilibrium constant between the two keto/enol tautomers. In order to do this GIAO/B3LYP/6-31G^∗∗ calculations of absolute shieldings (σ, ppm) were carried out. To establish relationships between σ and experimental chemical shifts (δ, ppm), three simple β-diketones (acetylacetone, dibenzoylmethane and benzoylacetone) have been studied. The preference for different groups to be conjugated with the CO has been determined.     

Oxidation of β-dicarbonyl compounds with tert-butyl hydroperoxide in the presence of vanadyl acetylacetonate

Oxidation of β-dicarbonyl compounds with tert-butyl hydroperoxide in the presence of vanadyl acetylacetonate (benzene, 20°C) involves the activated methylene group with intermediate formation of trioxo derivatives and is accompanied by decomposition of carbon skeleton. The oxidation products are carbon dioxide, carboxylic acids, and tert-butyl and peroxy esters derived from the latter.     

Reactions of β-aminopropionic acid N"-acylhydrazides with carbonyl compounds

The reactions of -aminopropionic acid N"-acylhydrazides with aromatic and heterocyclic aldehydes and acetone afford compounds that exist in solutions predominantly as mixtures of 2-substituted 3-acylaminotetrahydropyrimidin-4-ones (ATHP) and tautomeric Schiff"s bases. These compounds in the crystalline state probably have structures of ATHP. The ratio of tautomers depends on the type of substituent in the aromatic ring and solvent. The reactions of 2-aryl-3-benzamidotetrahydropyrimidin-4-ones with carboxylic or sulfonic acid chlorides afford derivatives of 1-acyl- and 1-tosyl-3-benzamidotetrahydropyrimidin-4-ones.     

Bifunctional metal-free photo-organocatalysts for enantioselective aerobic oxidation of β-dicarbonyl compounds

A series of bifunctional metal-free photo-organocatalysts have been developed by grafting the photosensitizer to cinchona-derived phase-transfer catalysts. Using air as a green oxidant and visible light as the driving force, these catalysts are applied to the oxidation of a range of β-dicarbonyl compounds in good yields (up to 97%) and enantioselectivities (up to 93:7 er).     

Reactions of β-keto sulfones with t-butyl aluminum compounds: Reinvestigation of tri-t-butyl aluminum synthesis

t-Butyl derivatives play a significant role in the organometallic chemistry of group 13 metals. It was shown on the basis of reactions of t-Bu₃Al·OEt₂ with [p-RC₆H₄S(O)₂C(H)₂C(Ph) = O] (where R = CH₃, Cl) β-keto sulfones that the structure of the reaction products depends on the purity of the aluminum compound used. In the reactions, in addition to the expected complexes [p-RC₆H₄S(O₂)C(H) = C (Ph)-OAl(t-Bu)₂] [where R = CH₃ ( 2 ); R = Cl ( 4 )] possessing β-keto sulfone ligands, complexes with β-hydroxy sulfone ligands [p-RC₆H₄S(O₂)C(H)₂-C (Ph)-OAl(t-Bu)₂] [where R = CH₃ ( 1 ); R = Cl ( 3 )] were formed. Compounds 1 and 3 were the result of the hydroalumination reaction of the β-keto sulfone ligands with t-Bu₂AlH, which is an impurity of t-Bu₃Al. These compounds are obtained, for the first time, as intermediate products in the hydrogenation reaction of β-keto sulfones. In this work, during t-Bu₃Al·OEt₂ production t-Bu₂AlH·OEt₂ formed as a by-product. Re-examination of reaction conditions of AlCl₃ with t-BuMgCl resulted in a control of the t-Bu₂AlH·OEt₂ by-product content in t-Bu₃Al·OEt₂.     

Theoretical study of spin-spin coupling constants in thecis-enol forms of β-dicarbonyl compounds

The values of the spin-spin coupling constant J(CH) of the bridging proton in the cis-enol forms of -dicarbonyl compounds have been calculated with consideration of the one-dimensional distribution functions of the proton. The results have been compared with the experimental data obtained in the present investigation. The dependence of the spin-spin coupling constants considered on the parameters of the potential of the intramolecular hydrogen bond has been discussed.Institute of Bioorganic Chemistry, Academy of Sciences of the Belorussian SSR, M. V. Lomonosov Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 84–87, March–April, 1991.     

Synthesis of 1,3-thiazoline derivatives from β-dicarbonyl compounds and phenacyl thiocyanate

Acetylacetone and ethyl acetoacetate undergo addition at the CN bond of phenacyl thiocyanate in the presence of Ni(acac)₂ to give the respective keteneN, S-acetals, which undergo smooth cyclization to afford 2-methylene-4-phenyl-1, 3-thiazoline derivatives when refluxed in THF.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1938–1940, November, 1993     

IBX promoted one-pot condensation of β-naphthol,aldehydes, and 1,3-dicarbonyl compounds

Abstract

An efficient and mild protocol has been developed for one-pot condensation of β-naphthol, aldehydes, and 1,3-dicarbolyl compounds in presence of o-iodoxybenzoic acid has been found to be an excellent catalyst for the synthesis of tetrahydrobenzo[a]xanthen-one, 1H-benzo[f]chromen-2-yl)-one via one-pot three-component condensation of β-naphthol, aldehydes, and 1,3-dicarbonyl compounds. Short reaction time, ambient conditions, simple workup, and high yield with selective manner are some of the striking features of the present protocol.     

Highly enantioselective direct Michael addition of 1,3-dicarbonyl compounds to β-fluoroalkyl-α-nitroalkenes

Cinchona alkaloid catalysts were used in the Michael addition reaction of 1,3-dicarbonyl compounds to β-fluoroalkyl-α-nitroalkenes for the first time. The catalytic system performed well over a broad scope of substrates including β-keto esters and 1,3-diketones with high diastereoselectivities and excellent enantioselectivities (up to 99% ee) under mild conditions. A wide range of useful fluorinated chiral building blocks was synthesized.     

Reactions of regioisomeric fluoroalkyl-containing β-aminovinyl ketones with hydrazines

Fluoroalkyl -alkyl--aminovinyl ketones react with hydrazine hydrate to give the respective razoles and with phenylhydrazine they form a mixture of pyrazoles and 5 hydroxy-²-pyrazolines. Alkyl(aryl) -fluoroalkyl--aminovinylketones do not react with the hydrazines mentioned above. With 2,4-dinitrophenylhydrazine, both types of fluoroalkyl-containing -aminovinyl ketones give only hydrazones of the corresponding methyl alkyl(aryl) ketones.     

Reactions of β-alkoxyvinyl trihalogenomethyl ketones with triethyl phosphite

The Perkow reaction of triethyl phosphite and β-alkoxyvinyl trihalogenomethyl ketones, which have common acyclic or cyclic structural fragment: -O-CC-C(O)CX₂Cl, yielded dienyl phosphates: -O-CC-C[OP(O)(OEt)₂]CX₂ where X = F or Cl, whereas γ-bromo-β-methoxy-α,β-unsaturated trifluoromethyl ketone CF₃C(O)CHC(OMe)CH₂Br gave diene CF₃C[OP(O)(OEt)₂]CH-C(OMe)CH₂.