S. I. Firgang

1,3-Cyclohexanedione in the Synthesis of Fused Derivatives of 4,7-Phenanthroline

Abstract12-Aryl(heteryl,cyclohexenyl)-8,9,10,12-tetrahydro-7H-benzo[b][4,7]phenanthrolin-11-ones were synthesized by condensation of 1,3-cyclohexanedione with 6-quinolylamine and aldehydes of aromatic, heterocyclic, and cyclohexene series.

Inhibition of monoamine oxidase by indole-5,6-dicarbonitrile derivatives

Recent studies have found that phthalonitrile derivatives are remarkably potent inhibitors of human monoamine oxidase (MAO) A and B. In an attempt to further determine the structure-activity relationships (SARs) for MAO inhibition by this class of compounds and to discover novel potent MAO inhibitors, the present study investigated the MAO inhibition properties of a series consisting of indole-5,6-dicarbonitrile derivatives. The results document that 3-chloro-1H-indole-5,6-dicarbonitrile derivatives exhibited potent inhibition of the MAOs. For example, 3-chloro-2-(4-methylphenyl)-1H-indole-5,6-dicarbonitrile inhibited MAO-A and MAO-B with IC50 values of 0.014μM and 0.017μM, respectively. It was further shown that this compound acts as a reversible and competitive inhibitor of both MAO isoforms. An analysis of the SARs for MAO inhibition by 3-chloro-1H-indole-5,6-dicarbonitriles showed that methylation of the indole nitrogen eliminates MAO-B inhibition activity, and replacement of the 2-phenyl ring with the thienyl results in a 9-fold reduction of MAO-B inhibition activity. A series of 3-bromo-1-hydroxy-1H-indole-5,6-dicarbonitriles are, in turn, comparatively weaker MAO inhibitors. It may be concluded that indole-5,6-dicarbonitrile derivatives are suitable leads for the design MAO inhibitors for the treatment of disorders such as Parkinsons disease and depression.

Reaction of Methylcyclohexanones with Substituted Benzaldehydes and 2-Naphthylamine

Cascade heterocyclization of 3(4)-methylcyclohexanone, substituted benzaldehyde, and 2-naphthyl-amine in a polar solvent in the presence of hydrochloric acid afforded the corresponding 5-aryl-2(3)-methyl-1,2,3,4-tetrahydrobenzo[a]phenanthridines and 12-aryl-9(10)-methyl-8,9,10,11-tetrahydrobenz[a]acridines

CONDENSATION OF 5-AMINO-4-ARYLPYRAZOLES WITH ITACONIC ACID AND MALEIC ANHYDRIDE

Substituted 5-amino-4-arylpyrazoles on condensation with itaconic acid form substituted tetrahydropyrazolo[1,5-a]pyrimidines, and on condensation with maleic anhydride form 2,3-dihydro-1H-imidazolo[1,2-b]pyrazoles, which on more extended heating rearrange into tetrahydro-pyrazolo[1,5-a]pyrimidines.

Cyclization of 2-arylamino-1,4-naphthoquinones to benzo[b]phenazine-6,11-dione 5-oxides

A method for the synthesis of a new group of tetracyclic diazaquinones, viz., benzo[b]-phenazine-6,11-dione 5-oxides, was developed and the pathways of their further modifications were outlined.

Synthesis of chiral chromenes from levoglucosenone

Levoglucosenone, an optically active α,β-unsaturated ketone available from cellulose, undergoes a stereoselective oxa-Michael-aldol domino reaction with 2-hydroxybenzaldehydes with the formation of optically active oxepino[4,5-b]chromen-1-ones. These compounds attacked by nucleophiles undergo recyclization to 4-substituted oxepino[3,4-b]chromen-11a-ols, while their oximes treated with SOCl2 are converted to 3-cyano-2H-chromenes through the Beckmann fragmentation.

Synthesis and structures of 4,6-disubstituted 2-(5-methyl-1,2,4-oxadiazol-3-yl)-1,3,5-triazines

New 1,2,4-oxadiazolyl-1,3,5-triazines were synthesized from amidoximes derived from sym-triazine mononitriles. The structure of one of the resulting compounds was studied in detail by X-ray diffraction.

New Method for Synthesis of the Hetero-Cyclic System – 1,2,3,4-Tetrahydro-Imidazo[5,1-f][1,2,4]Triazin-7-Amine

Imidazotriazines are used as dyes, luminophores, and corrosion inhibitors [1, 2]. Earlier these compounds were obtained on the basis of diaminopyridinium salts, and this was not economically feasible. We decided to study an alternative method for the preparation of imidazotriazines starting from 1,2-diaminoimidazoles. In the course of the investigations we found that 1,2,3,4-tetrahydroimidazo[5,1-f][1,2,4]triazin-7-amines 4a-e are formed during the reaction of 1,2-diaminoimidazoles 1a-c, obtained by the reaction between benzaldehyde guanylhydrazones and halo ketones [1], with formaldehyde and primary amines 2a,b.

2,6,7-Trihydroxy-4,9-dioxodeca-2,5,7-trienoic and 2-hydroxy-2-(3-hydroxy-4-methyl-2,5-dioxocyclopent-3-en-1-ylidene)acetic acid esters: Synthesis and structural specificity

Claisen condensation of acetone and butan-2-one with diethyl oxalate in the presence of metallic sodium leads to the formation of ethyl 2,6,7-trihydroxy-4,9-dioxodeca-2,5,7-trienoate and ethyl 2-hydroxy-2-(3-hydroxy-4-methyl-2,5-dioxocyclopent-3-en-1-ylidene)acetate, respectively.

Structure of reaction products of substituted [1,3]thiazolo[3,2-b][1,2,4]triazol-6(5H)-ones with amines and hydrazines

Reactions of 2-(4-methylphenyl)[1,3]triazolo[3,2-b][1,2,4]thiazol-6(5H)-one and 5-benzylidene-2-(4-methylphenyl)[1,3]thiazolo[3,2-b][1,2,4]triazol-6(5H)-one with amines and hydrazines of diverse structures were studied. The structure of the reaction products was established.