A. V. Baranovskii

Reductive transformations of Schiff bases in the synthesis of functionally substituted heteroaromatic amines

Schiff bases synthesized by condensation of 5- and 6-aminoquinolines, 5-amino-2-methylquinoline, nitroanilines, and pyrimidinylaminoanilines with substituted benzaldehydes and pyridinecarbaldehydes were reduced with sodium tetrahydridoborate in acetic acid to obtain the corresponding N-aryl(hetaryl)benzylamines, N-(pyridylmethyl)anilines, and N-(1,2,3,4-tetrahydroquinolyl)benzylamine derivatives. The reduction of arylhetarylimines with hydrazine hydrate in the presence of Raney nickel involved only the azomethine C=N bond, while the nitrogen-containing heteroaromatic ring remained intact. Under analogous conditions, nitrosubstituted Schiff bases and benzyl- and pyridylmethylamines were converted into previously unknown N-(aminobenzyl)quinolinamines and aryl(pyridyl)methyl-substituted phenylenediamines.

Synthesis of 6-deoxo-24-epiteasterone and its analogs

Selective reduction of the C8=C14 double bond in 3-hydroxyergosta-8(14),22-dien-15-one, followed by cis-hydroxylation of the double bond in the side chain and reduction of the 15-oxo group gave new 3β-hydroxy-6-deoxobrassinosteroids, their 22S,23S isomers, and the corresponding esters. The side chain in the products is identical to that in such known natural brassinosteroids as 24-epibrassinolide and 24-epicastasterone.

Regioselective synthesis of polyfluoroalkyl-substituted 7-(1H-1,2,3-triazol-1-yl)-6,7-dihydro-1H-indazol-4(5H)-ones

Abstract3-Polyfluoroalkyl-6,6-dimethyl-7-(1H-1,2,3-triazol-1-yl)-6,7-dihydro-1H-indazol-4(5H)-ones were synthesized with high regioselectivity by 1,3-dipolar cycloaddition of terminal alkynes (phenylacetylene, hex- 1-yne, hept-1-yne, and but-3-yn-1-ol) to 7-azido-6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol-4(5H)-ones which were prepared by bromination of 6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol- 4(5H)-ones with N-bromosuccinimide in anhydrous carbon tetrachloride, followed by treatment of the corresponding 7-bromo derivatives with sodium azide.

Synthesis of perfluoroalkyl-substituted 4,5-dihydro-3H-pyrazolo[4,3-a]phenazines and tetrahydroimidazo[4,5-e]indazoles

Oxidation of 1-aryl-3-perfluoroalkyl-6,7-dihydro-1H-indazol-4(5H)-ones with selenium dioxide in the presence of sulfuric acid in glacial acetic acid, followed by treatment of 6,7-dihydro-1H-indazole-4,5-diones thus obtained with an equimolar amount of o-phenylenediamine in ethanol or with a mixture of 4-fluorobenzaldehyde and ammonium acetate in acetic acid, gave 3-aryl-1-perfluoroalkyl-4,5-dihydro-3H-pyrazolo-[4,3-a]phenazines and 6-aryl-2-(4-fluorophenyl)-8-perfluoroalkyl-1(3),4,5,6-tetrahydroimidazo[4,5-e]indazoles, respectively.

Synthesis and transformations of perfluoroalkyl-containing 6,7-dihydro-1H-indazol-4(5H)-ones oximes

Refluxing 3-perfluoroalkyl-6,7-dihydro-1H-indazol-4(5H)-ones with 4-fold excess of hydroxylamine hydrochloride in pyridine afforded their (E)-oximes. The obtained oximes were alkylated with ethyl iodide and acylated with carboxylic acids chlorides to obtain (E)-O-alkyl- and (E)-O-acyloximes respectively. Heating oximes in PPA at 120°C results in their aromatization by Semmler-Wolff reaction, hydrolysis of perfluoroalkyl groups, and generation of 4-amino-1-aryl-5,6-dimethyl-1H-indazole-3-carboxylic acids from of 3-tri-fluoromethylindazolone oximes and 1-(4-amino-1-aryl-5,6-dimethyl-1H-indazol-3-yl)-fluoroalkan-1-ones from of 3-perfluoroethyl- and 3-perfluoropropylindazolone oximes.

Synthesis of 15β-hydroxyalkyl-substituted (17Z)-pregn-17-enes, their ethers and esters

Proceeding from Δ15-17-ketosteroids via copper(I)-catalyzed 1,4-addition of Grignard reagent followed by modification of the 15-alkenyl substituent, introduction of a 17-ethylidene component via Wittig reaction, and transformations in the A and B rings of the steroid molecule we obtained a series of 15β-hydroxyalkyl-substituted (17Z)-pregn-17-enes, their ethers and esters.

Chemical Transformations of 5,5-Dimethyl-2-(3-aryl-4-nitrobutanoyl)cyclohexane-1,3-diones. Synthesis of 6,7-Dihydrobenzo[d]isoxazol-4(5H)-ones and 6,7-Dihydro-1H-indazol-4(5H)-ones with Isoxazole and Isoxazoline Fragments in the Side Chain

By reaction of 5,5-dimethyl-2-(3-aryl-4-nitrobutanoyl)cyclohexane-1,3-diones with hydroxylamine and hydrazine hydrate 6,7-dihydrobenzo[d]isoxazol-4(5H)-ones and 6,7-dihydro-1H-indazol-4(5H)-ones were prepared containing a nitromethyl substituent in the side chain. Basing on the nitromethyl group of the latter nitrile oxide intermediates were generated that were brought into reaction of 1,3-dipolar addition with phenylacetylene, styrene, and vinyl ethyl ether with the formation of the corresponding isoxazole and isoxazoline derivatives.

Features of the synthesis of 1,1′-Phenylenebis(1H-tetrazoles) and their transformations in basic environment

Reactions of substituted 1,3- and 1,4-phenylenediamines with sodium azide and triethyl orthoformate in the presence of acetic acid led to the formation in high yields of the corresponding 1,12 -phenylenebis(1Htetrazoles). The presence of electron-acceptor groups in the molecules of the initial diamines reduces the yield of the target heterocycles. With 2-nitro-1,4-phenylenediamine the prevailing product was 2-nitro-4-(1H-tetrazol-1-yl)aniline. The obtained bistetrazoles in basic environment suffer an opening of one or both heterocycles forming cyanamides.

3-acyl-1,2,3,4-tetrahydropyridine-2,4-diones: Synthesis and chemical properties

N-Substituted 6-methyl-1,2,3,4-tetrahydropyridine-2,4-diones reacted with aliphatic carboxylic acid chlorides in the presence of pyridine or triethylamine to give the corresponding 4-O-acyl derivatives which underwent O,C-migration of the acyl group by the action of 2 equiv of triethylamine and a catalytic amount of 2-hydroxy-2-methylpropanenitrile. Reactions of 3-acyl-6-methyl-1,2,3,4-tetrahydropyridine-2,4-diones thus formed with aliphatic and aromatic amines gave the corresponding enamino derivatives at the side acyl group. Enamino derivatives at the C4 =O group were obtained by transformation of 3-acyl-1,2,3,4-tetrahydropyridine-2,4-diones into 3-acyl-4-methoxy-6-methyl-1,2-dihydropyridin-2-ones via alkylation with dimethyl sulfate and subsequent treatment with amines.

A New Synthesis of Zymosterol

A modified scheme for the synthesis of zymosterol, one of the biosynthetically important yeast sterols, starting from 3-benzoyloxyergosta-8(14),22-dien-15-one has been suggested.