V. S. Troitskaya

Investigations of pyrans and related compounds

The action of phosphorus oxychloride in DMFA on 4-hydroxy-3-nitrocoumarin has given 4-chloro-3-nitrocoumarin, by the reaction of which with amines and ammonia 4-amino-3-nitrocoumarins have been synthesized; some of their physicochemical properties have been studied.

Studies of pyrans and related compounds

The fine structures of the products of the cleavage of the heterorings of chromones and 4-pyrones by ammonia and primary and secondary amines, i.e., 2-β-aminoacrylylphenols (I) and di(β-aminovinyl) ketones (II), were studied by means of IR and PMR spectra, and it was established that I and II, which contain amino groups with a hydrogen atom attached to the nitrogen, exist in the cis form with double intramolecular (chelate) bonding between one carbonyl and two proton-containing groups.

Research on pyranes, their analogs, and related compounds

Reaction of sodium azide with chromone-2-carbonyl chloride or the action of nitrous acid on the hydrazide of chromone-2-carboxylic acid, existing in the cyclic form 3′-oxopyrazolidino[4′,5′∶2, 3]-chroman-4-one, gives the azide of chromone-2-carboxylic acid, the Curtius rearrangement of which is used to synthesize a number of 2-acylaminochromones.

Vibrational spectra of pyrazole in various aggregate states and their interpretation

The selection of the fundamental frequencies of pyrazole and the assignment of them to various types of vibrations were made on the basis of a comparison of the IR and Raman spectra of pyrazole and some of its isotopically substituted derivatives in various aggregate states and in the form of complexes with CdCl2. The assignment was confirmed by prior calculation of the frequencies and forms of the vibrations of pyrazole.

Effect of hydrogen bonding on the frequency of the out-of-plane deformation vibrations of the NH bonds in pyrazole and imidazole molecules

The assignment of the frequency of the out-of-plane deformation vibration of pyrazole on the basis of an investigation of the temperature dependence of the IR spectrum is reexamined.

Tautomerism of 1-phenyl-3-methyl-4-benzyl-5-pyrazolone

The tautomerism of 1-phenyl-3-methyl-4-benzyl-5-pyrazolone —a side product in the reaction of acetoacetic ester with benzaldehyde phenylhydrazone — was studied by IR and PMR spectroscopy, and its thermodynamic characteristics were determined.

Synthesis and study of the properties of 4-substituted 3-aminomethylcoumarins

The aminomethylation of 4-hydroxycoumarin gave 3-pyrrolidinomethyl- and 3-piperidinomethyl-4-hydroxycoumarins, which were converted to 4-chloro derivatives by the action of phosphorus oxychloride. A number of 3-pyrrolidinomethyl- and 3-piperidinomethyl-4-aminocoumarins were synthesized by reaction of the 4-chloro derivatives with various amines, and some of their properties were studied.

Research into analogs of pyran and related compounds: XXX. The reaction of 2-methoxycarbonyl-4,4-dichloro-2-chromene with 1-piperidino-1-cyclohexene

The reaction of 2-methoxycarbonyl-4, 4-dichloro-2-chromene with 1-piperidino-1-cyclohexene, for example, shows the high alkylating ability of 4, 4-dichlorochromenes toward enamines. In this case, the reaction is accompanied by the transfer of the reaction center in the dichloro compound from the 4-to the 2-position (allyl rearrangement), resulting (after acid hydrolysis) in the formation of 2-methoxycarbonyl-2-(2′-oxo-1′-cyclohexyl)-4-chloro-3-chromene in two diastereoisomeric pairs (IIa and b). The structure of compounds IIa and b is proved by hydrogenation to the diastereoisomeric 2-methoxycar-bonyl-2-(2′-oxo-1′-cyclohexyl) chromans (IIIa and b) and examination of the NMR spectra of the latter. Hydrazides (IVa and b) were obtained from IIa and b, compound IVb then being cyclized to the intramolecular acylhydrazone V, which provides additional support for the structure II.

The structure of the products of the opening of the pyrone ring of chromones by amines

The fine structure of the products of the opening of the pyrone ring of chromones by amines-2-(β-aminoacryloyl)phenols — has been determined.

Tautomerism of 2-acylamino-3-dialkylaminomethylchromones

The determination of the ionization constants and UV, IR, and PMR spectroscopy established that 2-acylamino-3-dialkylaminomethylchromones can, depending on the character of the acyl group, the aggregate state, and the nature of the solvents, exist in the chromone form with an intramolecular hydrogen bond or as a zwitterion.