Synthesis of tetra- and octahydroxanthene derivatives by the condensation of dimedone with aromatic aldehydes

The reaction of dimedone with salicyl and 2-hydroxy-1-naphthoyl aldehydes gave derivatives of tetrahydroxanthene and tetrahydrobenzo[a]xanthene and not aldimedone as occurs in condensations with other aldehydes. Derivatives of decahydroacridine were obtained by reaction of the tetrahydroxanthene derivatives with methyl-and ethylamine. Tetrahydro- and octahydroxanthene derivatives were obtained from the reaction of acetylsalicylaldehyde with dimedone in acetic anhydride. The structures of the ketoenol forms of the products containing a-ketoenol unit were determined by¹H and¹³C NMR spectroscopy, and the mechanism of their interconversion is discussed.Institute of Bioorganic Chemistry, Belarus Academy of Science, Minsk, 220141. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 742–753, June, 1996. Original article submitted February 22, 1996.     

Synthesis of pyrazolines by the condensation of monoalkyl hydrazones with aldehydes

Acetaldehyde readily condenses with its monalkyl hydrazones with the formation of 1-alkyl-5-methyl-2-pyrazolines. A number of pure 2pyrazolines have been synthesized in this way with yields of 40–60%. In the condensation of propionaldehyde with its isopropyl hydrazone, because of the occurrence of rearrangements and the nonstereospecificity of the process, a mixture of structural and stereoisomeric 2-pyrazolines is formed. The promising condensation of aldehydes with monalkyl hydrazones of other aldehydes and ketones is accompanied by transhydrazonation, which limits the preparative possibilities of this reaction.From the text of the thesis of N. B. Burmanova, defended in May, 1967.     

One‐Pot Synthesis of Pentasubstituted Cyclohexanes by a Michael Addition Followed by a Tandem Inter–Intra Double Henry Reaction

Michael, Henry, and Henry : A new one‐pot reaction of α,β‐unsaturated aldehydes and β‐dicarbonyls, which involves a Michael reaction catalyzed by diarylprolinol ethers and an inter–intramolecular Henry tandem reaction catalyzed by TBAF (see scheme), has been developed. The reaction proceeds in high enantio‐ and diastereoselectivity for a wide range of unsaturated aldehydes and β‐dicarbonyl reagents.

     

Reaction of 1,4-bis(trimethylsilyl)-2-butene with aromatic aldehydes catalyzed by TiCl4: an approach to (1-vinylallyl)benzene type derivatives

1,4-bis(Trimethylsilyl)-2-butene 1 can react with alkyl and aromatic aldehydes in the presence of titanium tetrachloride to give α-(trimethylsilyl)methyl homoallylic alcohols and (1-vinylallyl)benzene type compounds in poor to good yield according to the related position of each substituents present on the aromatic ring. In the last case, the reaction involves a type electrophilic substitution of 1,4-bis(trimethylsilyl)-2-butene by aromatic aldehydes activated by TiCl₄, followed by a 1,2-migration of a vinyl group.     

Chelating alkoxy NHC–Rh(I) complexes and their applications in the arylation of aldehydes

In this study, new rhodium(I) complexes (5 and 6) have been prepared by the reaction of [RhCl(COD)]₂ with a series of imidazolium salts (3 and 4), which were obtained from a chiral amino alcohol. The catalytic activities of these complexes were tested in the arylation of aldehydes. It was found that the synthesized rhodium complexes were highly effective catalysts for the arylation of aldehydes in short reaction times (5 min, TOF = 1193 h⁻¹). However, the obtained ee values (up to 32% ee) remained low. We have proposed a mechanism for the arylation reaction of aldehydes, which is confirmed via ¹⁹F NMR spectroscopy.     

New and efficient conditions for the Z-selective synthesis of unsaturated esters by the Horner-Wadsworth-Emmons olefination

The Horner-Wadsworth-Emmons reaction of both 1 (Still's reagent) and 2 (Ando's reagent) with aldehydes was studied. Tris[2-(2-methoxyethoxy)ethyl]amine (TDA-1) was shown to be an efficient additive when the reaction was performed in THF at −78 °C. Selectivities close to 95% were obtained in the condensation of 1 with aromatic aldehydes. The use of a 5-fold excess of 18C6 in this reaction had already been reported. However, we have defined conditions in which only catalytic amounts are required.     

Reaction of triethyl-N-ethyleniminosilane with aldehydes

The action of alphatic, aromatic and heterocyclic aldehydes on triethyl-N-ethyleniminosilane in the presence of water gives-alkyl (aryl)--N-ethyleniminomethoxysilanes of the type (R = Et; R = alkyl, aryl, furyl). Similarly dimethyldi-N-ethylenimisoline and acetaldehyde give reaction mechanism is suggested.     

Kinetics and mechanism of oxidation of aliphatic aldehydes by peroxomonosulphate

The kinetics of the oxidation of aliphatic aldehydes, formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, and trichloroacetaldehyde by Peroxomonosulphate (PMS) was carried out in aqueous perchloric acid medium (0.1–1 M H⁺) at constant ionic strength of 1.2 M in the temperature range 10°–60°C. The reactions of all the aldehydes were found to obey a total second-order kinetics, first order each with respect to [Peroxomonosulphate] and [aldehyde]. Acetaldehyde, propionaldehyde, and n-butyraldehyde exhibited acid catalysis with the concurrent occurrence of acid-independent reaction path conforming to the rate law Formaldehyde was found to undergo oxidation only by acid-dependent path (k_b = 0) and trichloroacetaldehyde exhibited only the acid-independent reaction path (k_a = 0). The products of oxidation were found to be the respective carboxylic acids in each case. The stoichiometry of the reaction, [Peroxomonosulphate]:[Aldehyde] = 1:1, indicated the absence of carbonyl-assisted decomposition and self-decomposition of peroxomonosulphate. The kinetic and thermodynamic parameters evaluated pointed to the mechanism of a fast nucleophilic attack of the oxidant on the aldehyde followed by slow acid catalyzed and/or uncatalyzed decomposition of the intermediate to product. A sharp comparison is made with the corresponding reactions of the similar peroxides, S₂O and H₂PO.     

Structure of the products of the reaction of 9,10-dimethylacridinium salts with aromatic o-hydroxy aldehydes

The reaction of 9,10-dimethylacridinium methosulfate with aromatic o-hydroxy aldehydes in alcohol in the presence of piperidine gives 10-methyl-4-(10-methyl-9-acridanylidenemethyl)-spiro[acridan-9,2-chromans]. The structure of the compounds obtained was established by means of the PMR, UV, and IR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 539–544, April, 1973.     

The reaction of diethyl oxalate with some azolidones

The condensation of thiazolidine-2, 4-dione, rhodanine, isorhodanine, 2-thiohydantoin, and pseudothiohydantoin with diethyl oxalate has given products which are azolidone-5-glyoxalic acids or their esters. In these compounds, the glyoxalic acid residue is readily replaced under the action of diazonium salts, aromatic nitroso compounds, and aromatic aldehydes with the formation of 5-arylazo-, 5-arylimino-, and 5-arylideneazolidones. 5-Arylidenerhodanines are also formed from 5-isopropylidene-and 5-(-acetyl--methylethylidene)rhodanines by their reaction with aromatic aldehydes and ketones.     

Study of the Kinetics of the Combustion Reaction on Shuangya Mountain Coal Dust by TG

The combustion behavior of Shuangya Mountain (SYM) coal dust has been investigated by means of TG in this paper. The reaction fraction can be obtained from isothermal TG data. The regressions of g(), an integral function of vs. t for different reaction mechanisms were performed. The mechanism of nucleation and nuclei growth is determined as the controlling step of the coal dust combustion reaction by the correlation coefficient of the regression, and the kinetic equation of the SYM coal dust combustion reaction has been established.This revised version was published online in November 2005 with corrections to the Cover Date.     

Pyrimidines

3-Arylbenzo[f]quinazolines were obtained by reaction in acetic or propionic acid of -naphthylamine, ammonia, and aromatic aldehydes containing an NR₂ or OH group. A mechanism is proposed for the formation of monoarylbenzo[f]quinazolines from the corresponding intermediate 1,3-diaryldihydrobenzo [f] quinazolines by acid cleavage of the C-aryl bond in the 1 position. This mechanism was confirmed experimentally by establishment of the fact of cleavage of 1,3-bis (p-methoxyphenyl)-1,2-dihydrobenzo[f] quinazoline when the acidity of the medium is increased; 3-(p-methoxyphenyl) benzo [f] quinazoline and anisole were obtained in the reaction products. Condensation in the presence of formic acid gave -arylidene-N-formyl--naphthylamines rather than arylbenzo [f] quinazolines.See [1] for communication LXIV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1265–1271, September, 1978.     

Synthesis of carboline bases

A study has been made of the condensation of serotonin with aldehydes to give the corresponding -carboline derivatives. In most cases the reaction was run under biological conditions (pH 5. 4, 36). The following aldehydes were reacted: acetaldehyde, butyraldehyde, isobutyraldehyde, benzaldehyde, n-octaldehyde, and formaldehyde. The corresponding -carboline derivatives are obtained from the first 5 of these. The reaction with formaldehyde leads to complete resinification.     

Vapor-Phase Conversion of Esters into Ketones in the Presence of an Sn-, Ce-, and Rh-Containing Oxide Catalyst

The catalytic conversion of acyclic and cyclic esters into ketones was studied. Based on an analysis of data on the yields of the products of ester conversion, the conclusion was drawn that ketones result from a reaction between two ester molecules with the intermediate formation of a -ketoester. This reaction is accompanied by the partial thermal decomposition of esters to aldehydes (reverse Tishchenko reaction) with the subsequent condensation.     

Study of the carbonyl products of terpene/OH radical reactions: detection of the 2,4-DNPH derivatives by HPLC-MS

The oxidation of the terpenes - and -pinene, limonene and ³-carene by hydroxyl radicals has been investigated in a fast-flow reactor coupled to a liquid nitrogen trap for collecting the carbonyl compounds. Identification of the products was performed via 2,4-dinitrophenylhydrazone (DNPH) derivatization of the carbonyls to form the mono- and di-DNPH derivatives, which were analysed by high-performance liquid chromatographic (HPLC)-DAD (diode array detector) and HPLC-mass spectrometry (HPLC-MS). Both electrospray ionization [ESI(–)] and atmospheric pressure chemical ionization [APCI(–)] were suitable for the detection of the DNPH derivatives of formaldehyde, acetaldehyde, myrtanal, campholene aldehyde, perillaldehyde, acetone, nopinone, trans-4-hydroxynopinone and 4-acetyl-1-methylcyclohexene. Also the mono-DNPH derivatives of the dicarbonyl compounds pinonaldehyde, endolim and caronaldehyde could be identified. The MS² spectra generated in the ion trap of the mass spectrometer allowed us to distinguish between aldehydes and ketones on the basis of the characteristic fragment ion m/z 163 for the aldehydes. For the quantitative analysis of the mono-DNPH derivatives, ESI(–) in combination with single ion monitoring (SIM) detection showed the lowest detection limits. For the quantification of the dicarbonyl compounds, the acid-sensitive di-DNPH derivatives had to be formed by keeping the acidity in the acid-catalysed derivatization reaction at about 1.7 mM H₂SO₄. Detection of these dicarbonyl compounds can only be performed by APCI(–) with somewhat lesser sensitivity than by HPLC-DAD.     

Comparison of Conventional and Microwave Assisted Reactions Giving Aromatic Oxazolidines

By reaction of aromatic aldehydes with (-)-ephedrine aromatic 1,3-oxazolidines can be obtained. The reaction was carried out either at conventional conditions or by microwave heating. The different diastereomeric ratios were determined by means of ¹H NMR spectroscopy.     

Selective oxidation of aromatic primary alcohols to aldehydes using molybdenum acetylide oxo-peroxo complex as catalyst

Selective oxidation of various aromatic alcohols to aldehydes has been carried out with very high conversion (90%) and selectivity (90%) for aldehydes using cyclopentadienyl molybdenum acetylide complex, CpMo(CO)₃(CCPh) (1) as catalyst and hydrogen peroxide as environmentally benign oxidant. Water-soluble Mo acetylide oxo-peroxo species is formed in situ after reaction of 1 with aqueous hydrogen peroxide during the course of reaction as catalytically active species. Interestingly even though the catalyst is homogeneous it could be recycled very easily by separating the products in organic phase and catalyst in aqueous phase using separating funnel. Even after five recycles no appreciable loss in alcohol conversion and aldehyde selectivity was observed.     

A practical procedure for the synthesis of multifunctional aldehydes through the Fukuyama reduction and elucidation of the reaction site and mechanism

A highly efficient heterogeneous Pd/C catalyst D1 was found to effect the reduction of thiol esters 1 to the corresponding aldehydes 2 with such a low catalyst loading as 0.5-1.0 mol %. The chemical properties of the Pd/C catalysts together with the XRF analysis reveal that the reduction is most likely to proceed on the solid surface of the Pd/C catalyst rather than in the solution phase outside the pores. A reaction mechanism through oxidative addition of Pd to the thiol esters 1 was postulated by detection of the oxidative addition intermediate by React IR analysis. A practical purification of 2 was accomplished by conversion to water-soluble bisulfite adducts 7.     

Synthesis of some 3-phenyloxazolidines with functional groups

N-(, -Dihydroxypropyl)aniline was subjected to reaction with aldehydes. It was proved that the reaction products are 3-phenyl-5-hydroxymethyloxazolidines. A number of 3-phenyl-5-acyloxymethyloxazolidines were obtained by the reaction of the latter with acid anhydrides.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 451–453, April, 1971.     

Mechanistic and Spectral Studies of the Ruthenium(III) Catalysed Oxidation of Sulfanilic Acid by Alkaline Hexacyanoferrate(III)

Summary. The kinetics of ruthenium(III) catalysed oxidation of sulfanilic acid (p-aminobenzenesulfonic acid) by hexacyanoferrate(III) in alkaline medium at a constant ionic strength of 2.5mol·dm^–3 has been studied spectrophotometrically using a rapid kinetic accessory. The reaction exhibits 2:8 stoichiometry (SNA:HCF(III)). The reaction showed first order kinetics in [hexacyanoferrate(III)] and [ruthenium(III)] and apparent less than unit order in both sulfanilic acid and alkali concentrations. The reaction rate increases with increasing ionic strength but the relative permittivity (_T) of the medium has a negligible effect on the rate of the reaction. Initial addition of reaction products did not affect the rate significantly. A mechanism involving the formation of a complex between sulfanilic acid and hydroxylated species of ruthenium(III) has been proposed. The active species of HCF(III) and ruthenium(III) are understood as [Fe(CN)₆^3–] and [Ru(H₂O)₅OH]²⁺, respectively. The main products were identified by IR, NMR, and mass spectral studies. The reaction constants involved in the different steps of mechanism are calculated. The activation parameters with respect to the slow step of the mechanism are computed and discussed and thermodynamic quantities are also calculated.