A. K. Tyltin

Cycloaddition in condensed isoindoles 1. Preparation of 2-aryl-3-methyl-4-oxo-3,4-dihydroquinazoline

Reaction of 6-methyl-5,6-dihydroisoindolo[2,1-a]quinazolin-5-one with maleimide derivatives has been studied under conditions of thermodynamic control. X-ray diffraction structural analysis showed that the reaction products are 2{2-[(E)-1-R-2,5-dioxopyrrolidinidenemethyl]phenyl}-3-methyl-4-oxo-3,4-dihydroquinazolines. These products are supposed to be formed by rearrangement of the corresponding Diels-Alder adducts formed involving the isoindole part of the molecule.

Criteria for establishment of three-dimensional structures of Diels-Alder adducts in the isoindole series. 2. Reaction of 1,2-disubstituted isoindoles with maleinimide derivatives

The Diels-Alder reaction of a series of 1,2-disubstituted isoindoles with maleinimide derivatives under conditions of kinetic and thermodynamic control was investigated. Criteria for the establishment of the three-dimensional structures of the adducts obtained were found. The possibility of supra-antara cycloaddition and the formation of 1∶2 adducts was demonstrated.

Condensed isoquinolines. 7.* Synthesis of derivatives of the new heterocyclic system thieno[3′,2′:5,6]-pyrimido[1,2-b]isoquinoline

Abstract4-Oxo-6, 11-dihydro-4H-thieno[3′, 2′.-5,6]-pyrinudo[1, 2-b]isoquinolines have been synthesized by the reaction of o-bromo-methylphenylacetonitrile with esters of substituted 2-aminothiophene-3-carboxylic acids. They were characterized as the hydrobromides and as the fee bases. The tautonterism of the bases in DMSO solution is discussed.

Synthesis and properties of novel dibenz[b,f]azocines

Abstract5-Acetyl- and 5-trifluoroacetyl-12-hydroxy-11-cyano-5,6-dihydrodibenz[b,f]azocines have been synthesized by intramolecular cyclocondensation of ethyl N-acetyl and N-trifluoroacetyl-N-[1-(cyanomethyl)benzyl]-anthranilates. Spectral data show that the hydroxyl group in 5-acetyl-12-hydroxy-11-cyano-5,6-dihydrodibenz[b,f]azocine takes part in transannular hydrogen bond formation with the acetamide group carbonyl oxygen. A study of the chemical properties of this compound has shown that its alkylation by p, Ω-dibromoacetophenone is accompanied by a Thorpe reaction to form 11-amino-5-acetyl-12-(p-bromo-bemoyl)-5,6-dihydro[b,f]dibenzofuro[2,3-d]azocine.

Electron structures of azoloisoindoles with a nodal nitrogen atom. 1. Derivatives of isoindolobenzimidazole and imidazo- and pyrazoloisoindoles

N-Methyl-substituted 1H-imidazo[2,1-a]isoindole, 5H-isoindolo[2,1-a]benzimidazole, and 3H-pyrazolo[5,1-a]isoindole were calculated by the PPP and CNDO/2 methods. On the basis of the canonical and localized MO it was concluded that the examined compounds can, to a first approximation, be regarded as 1,2-disubstituted iso-indoles, i.e., 10π-electron systems. The calculated data are in good agreement with the experimental UV spectra and the chemical properties of the investigated compounds.

X-ray crystallographic investigation of the adduct of 1-demethylamino-2-(4-bromophenyl-2H-isoindole with N-phenylmalemide

An unusual path for the reaction of 2-aryl-1-dimethylamino-2H-isoindoles with N-R-maleimides, leading to the imides of l,2-dihydronaphthalene-2,3-dicarboxylic adds, was established by x-ray crystallographic analysis.

Investigation of the mass-spectrometric fragmentation of some isoindole derivatives

The results of a mass-spectrometric investigation of isoindole derivatives have made it possible to ascertain specific pathways in their fragmentation that differ from those for analogous indole derivatives and to also confirm the previously advanced concept regarding the structures of isoindoles, which have a complete 10π-electron system with substantial interannular conjugation.

Alkylation and reduction reactions in the isoquino[2,3-a]quinazoline series

Protonation and methylation of 5-oxo-7,12-dihydro-5H-isoquino[2,3-a]quinazoline occur at the N(6) atom, while methylation of 5-oxo- and 6-methyl-5-oxo-6,6a,7,12-tetrahydro-5H-isoquino[2,3-a]quinazolines takes place at the N(13) atom; the degree of stereoselectivity varies depending on the presence of a substituent attached to N(13). Based on PMR spectral analysis utilizing the nuclear Overhauser effect, we have established the structure and studied the conformational behavior of the tosylate derivatives of cis-13-methyl-, trans-13-methyl-, and cis-6,13-dimethyl-5-oxo-6,6a,7-12-tetrahydro-5H-isoquino[2,3-a]quinazolinium ions.

Quantum-chemical investigation of the Diels-Alder reaction in condensed isoindoles with a nodal nitrogen atom

On the basis of calculated data on the electron structures of condensed isoindoles with a nodel nitrogen atom it is hypothesized that these compounds may act as dienes in the Diels-Alder reaction. Conclusions regarding the relative activities and the peculiarities of cycloaddition in the investigated structures were drawn from the static reactivity indexes obtained within the Pariser-Parr-Pople approximation.

Synthesis of pyrido[1,2-b][2,4]benzodiazepin-6(11H)-imines

Condensation of o-bromomethylbenzonitrile and α-bromo-o-cyanophenylmethane with 2-aminopyridines gives 6-amino-6,11-dihydropyrido[1,2-b][2,4]benzodiazepines. Quaternary 2-aminopyridinium salts are intermediates in these reactions.