A convenient method for the preparation of primary amines using tritylamine

A simple method for the preparation of primary amines by treating N-tritylamines with trifluoroacetic acid has been established. The N-tritylamines were prepared by the reaction of alkyl halides or alkyl p-toluenesulfonates with tritylamine, or by the reaction of alkyl bromides with lithium tritylamide.     

A convenient method for the selective reduction of amides to amines

A variety of amides have been selectively reduced to the corresponding amines via conversion to their thioamides and treatment with triethyloxonium tetrafluoroborate followed by sodium borohydride. This procedure is compatible with isolated and conjugated double bonds, esters, intro groups, and sulfonamides.     

A safe, convenient and efficient method for the preparation of heterocyclic N-oxides using urea·hydrogen peroxide

A novel, convenient, and high-yielding method has been developed for the preparation of heterocyclic N-oxides. The reaction uses the urea·hydrogen peroxide addition complex as a peroxide source for the in situ generation of trifluoroperacetic acid. The advantages of this method are easy handling of a stable, solid oxidant; high yields and simple removal of excess reagents and by-products.     

An efficient and improved procedure for preparation of triflyl azide and application in catalytic diazotransfer reaction

An efficient and improved procedure for preparation of triflyl azide and application in catalytic diazotransfer reaction are described. The amount of highly toxic reagents NaN₃ and Tf₂O, is significantly reduced comparing with the previous protocol.     

A convenient method for the assignment of the absolute configuration to cyclic amines

We have assigned the absolute configuration to trans-2,5-dimethylpyrrolidine and trans-2,6-dimethyl-piperidine through radical chlorination in ω-1 position of optically active amines, 2 and 5, of known absolute configuration, followed by cyclization. CD curves of 1f and 4g derivatives indicate that the reaction is stereospecific. The absolute configuration of trans-2,5-dimethyl-Δ³-pyrròline has also been determined.     

Reinvestigation of the grignard reactions with formic acid. A convenient method for preparation of aldehydes

Grignard reagents react with formic acid in tetrahydrofuran to produce aldehydes in relatively good yields Various aldehydes such as alkyl, aryl, allyl, benzyl and vinyl aldehydes were prepared from the corresponding Grignard reagents. The reaction with vinyl Grignard reagents proceeded with retention of configuration.     

A facile and convenient method for the preparation of macrocyclic diamides

A number of macrocyclic diamides have been synthesized from the reaction of a diacid dicarboxylic dichloride with primary diamino compound in the presence of magnesium oxide-silica gel at room temperature in good yields. Using urea and thiourea as well as diamines to produce the corresponding macrocycles in the range of 52–56% yields are also included in this paper. One of the major advantages of this method is simple regeneration of inorganic solid and its reuse through several cycles without a decrease in activity.     

A modified and convenient method for the preparation of N-phenylpyrazoline derivatives

Ten new N-phenylpyrazoline derivatives have been synthesized in high yields by condensation of chalcones with phenylhydrazine in the presence of potassium carbonate in reflux conditions. The workup is simple and involves treatment with ice-cold water. As compared with the previous method a considerable increase in the reaction rate with better yields has been observed. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1032–1036, July, 2006.     

A convenient method for the determination of the absolute configuration of chiral amines

A highly useful methodology that allows the determination of the absolute configuration of aliphatic and aromatic chiral amines based on the rationalization of stereoselective three-point interactions during chromatography on a rationally designed chiral stationary phase and conformational analysis of the elutes was developed. This approach is based on the broadly accepted chiral recognition mechanism of the Whelk-O 1 CSP and requires a facile derivatization of the amine and the determination of the lowest energy conformation of the corresponding t-Boc- or Z-derived carbamates. The absolute configuration determined by employing chiral structure activity relationships in HPLC analysis was verified by single-crystal X-ray analysis or studies with carbamoyl derivatives of amines of known configuration. The general validity and applicability of this methodology was demonstrated by analysis of seven carbamates derived from aliphatic and aromatic amines. Due to its simplicity and time-efficiency, i.e., ease of derivatization of amines and fast HPLC method development, this approach can be considered a useful supplement to established techniques such as NMR spectroscopy.     

A convenient method for the preparation ofN-unsubstituted hydrazones of aromatic ketones and aldehydes

A general and useful method for the synthesis ofN-unsubstituted hydrazones of aromatic ketones and aldehydes in good yields was elaborated. The use of a large excess of hydrazine hydrate and catalytic amounts ofp-toluenesulfonic acid makes it possible to prepare the hydrazones without an admixture of the corresponding azine. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2197–2199, November, 1999.     

A convenient method for the preparation of 3-trimethylsilyl-2,5-dihydrofurans and their conversion to furans

Hydromagnesiation of 3-trimethylsilyl-2-propyn-1-o1 (1) followed by reaction with aldehydes or ketones affords (E)-3-trimethylsilyl-2-alken-1,4-diols (2), which can be readily dehydrated to 3-trimethylsilyl-2,5-dihydrofurans (3) by treatment with BF₃OEt₂. The compounds (3) are converted to furans (5) by epoxidation and subsequent treatment with H₂SO₄.     

A convenient method for the preparation of barbituric and thiobarbituric acid transition metal complexes

A convenient method for the preparation of barbiturate transition metal complexes: (i) Cr(3+), Mn(2+), Fe(3+), Zn(2+) and Cd(2+) ions with barbituric acid (H(2)L) and (ii) Cr(3+) and Mo(5+) with 2-thiobarbituric acid (H(2)L') was reported and this has enabled seven complexes to be formulated as: [Cr(HL)(2)(OH)(H(2)O)].H(2)O, [Mn(HL)(2)(H(2)O)(2)], [Fe(2)(L)(OH)(3)(H(2)O)(4)].2H(2)O, [Zn(HL)(2)], [Cd(HL)(2)], [Cr(HL')(OH)(2)(H(2)O)].H(2)O and [Mo(HL')(2)]Cl. These new barbiturate complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, (1)H NMR, mass, X-ray powder diffraction and UV/vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. The molar conductance measurements proved that, all complexes of barbituric and 2-thiobarbituric acids are non-electrolytes except for [Mo(HL')(2)]Cl. The electronic spectra and magnetic susceptibility measurements were used to infer the structures. The IR spectra of the ligands and their complexes are used to identify the mode of coordination. Kinetic and thermodynamic parameters such as: E, DeltaH, DeltaS and DeltaG are estimated according to the DTG curves. The two ligands and their complexes have been studied for their possible biological antifungal activity.     

A convenient method for the preparation of cyclohepta[b]indole derivatives

Cyclohepta[b]indole derivatives 7 were prepared by subsequent aza-Claisen rearrangement and intramolecular ring-closure of (cycloheptenylmethyl)benzenamine (3). The mechanisms of the reactions are also discussed.     

A convenient method of preparing nickel(II) thiocyanate and its use in synthesis

Summary A convenient method for preparing nickel(II) thiocyanate is described. Some new compounds containing nickel thiocyanate and ligands, such as OPPh₃, OAsPh₃, bipy, Me₂NH, Et₃N or N₂H₄ are reported, together with their structures and the nature of the bond between the thiocyanate and the metal, which has been determined by physical and chemical methods.     

A new spectrophotometric method for the determination of primary aromatic amines

A new spectrophotometric method for the assay of primary aromatic amines with metol-chromium(VI) reagent has been developed. The method is simple, reproducible and accurate within +/- 1.0%. It has been extended to the determination of drugs (in pure samples and pharmaceutical preparations) which either contain a free primary aromatic amine or release it through hydrolysis or reduction. The method is also applicable to the assay of p-aminobenzenesulphonamides in rat urine and blood. All the sulphonamide derivatives tested, as well as other aniline derivatives with an electron-withdrawing group in the para-position, afford nearly the same molar absorptivity. Depending on the absorptivity, 0.3-2 mumole of amine will give an absorbance of approximately 0.1.     

A convenient method for the preparation of fluorous tin derivatives for the fluorous labeling strategy

A convenient method for the preparation of fluorous aryl stannanes was developed as a means of expanding the general utility of the fluorous labeling strategy (FLS). Following the synthesis of a novel fluorous distannane, a palladium-catalyzed cross-coupling reaction was used to prepare the target compounds from aryl halides. The scope of the reaction was investigated by preparing a small library of model compounds where the reaction yields were similar to those reported for the analogous procedures employing hexamethyl- or hexabutyldistannanes. The utility of the reported methodology was demonstrated through the successful synthesis of fluorous precursors to two established molecular imaging and therapy agents (FIAU, IUdR). These were radiolabeled with iodine-125 and the desired products isolated in high yield and effective specific activity.     

A simple and convenient one-pot method for the preparation of heteroaryl-2-imidazoles from nitriles

A simple, convenient and high-yielding one-pot method for the synthesis of 2-heterocycle-substituted imidazoles from the corresponding nitriles has been developed. The procedure is easily scaleable and the workup does not involve chromatography. This synthesis is also applicable to the preparation of imidazoles with electron-poor aryl substituents.     

Synthesis of 1-substituted tetrazoles by heterocyclization of primary amines,orthoformic ester,and sodium azide

It has been shown that the reaction of heterocyclization of primary amines with orthoformic acid and sodium azide in acetic acid has a rather general character and is a convenient method for the synthesis if 1-substituted tetrazoles. On the basis of experimental data, a probable reaction mechanism is proposed.Translated from Khimiva Geterotsiklicheskikh Soedinenii, No. 11, pp. 1521–1524, November, 1985.