O. V. Dyablo

H-Bond-Assisted Intramolecular Nucleophilic Displacement of the 1-NMe2 Group in 1,8-Bis(dimethylamino)naphthalenes as a Route to Multinuclear Heterocyclic Compounds and Strained Naphthalene Derivatives

It has been shown that azomethines, hydrazones, and oximes derived from 2(7)-carbonyl derivatives of 1,8-bis(dimethylamino)naphthalene can undergo acid-catalyzed heterocyclization leading to a nucleophilic displacement of the 1-NMe(2) group. The process is believed to be directly connected with the proton sponge nature of the substrates, in which 1-NMe(2), being a poor leaving group, is preliminary activated via the formation of a chelated protonated form. A number of difficult to access derivatives of benzo[g]indazole, benzo[g]quinazoline, naphtho[2,1-d]isoxazole, and 8-dimethylamino-1-naphthol have been prepared in moderate to high yields.

4,5-Bis(dimethylamino)quinolines: proton sponge versus azine behavior.

Two first representatives, 5 and 6, of the still unknown 4,5-bis(dimethylamino)quinoline have been synthesized and studied. While the former, being protonated either at the peri-NMe(2) groups or at the ring nitrogen, has been shown to display properties of both a proton sponge and azine, its counterpart 6 behaves exclusively as azine giving only a quinolinium salt.

Synthesis of 4,5-Bis(Dimethylamino)Quinolines and the Dual Direction of their Protonation

A study on the synthesis of derivatives of 4,5-bis(dimethylamino)quinoline, which is a quinoline analog of 1,8-bis(dimethylamino)naphthalene (also known by its trade name Proton Sponge) was carried out. The first two representatives of this series were obtained. Depending on the aggregate state, solvent, and structural features, these compounds may be protonated either at the quinoline heteroatom or peri-NMe2 groups.

Synthesis and some properties of 1-(N-Nitrosoalkylamino)benzimidazoles

Abstract 1-(N-Nitrosoalkylamino)benzimidazoles (7a-e) were prepared by nitrosation of the parent amines with nitrous acid. The NMR data revealed 7a-d in solutions as mixtures of E and Z-isomers due to hindered rotation around the NNO bond. 1-(N-Nitrosoisopropylamino)benzimidazole (7e) existed in solutions as a sole Z-isomer. The rotation barrier around the NNO bond was estimated for 7a by 1H NMR dynamic spectroscopy. The molecular structure of 1-(N-nitrosomethylamino)-2-methylbezimidazole (7d) was confirmed by X-ray structural data.

Synthesis of 6-methoxy-N2,N2,N4,N4,N5,N5-hexamethylquinoline-2,4,5-triamine – a new representative of quinoline proton sponges

We report the synthesis of 4-chloro-2-methyl-5-nitro- and 2,4-dichloro-5-nitroquinolines, containing methoxy groups at positions 6 and 8. The reaction of these compounds with dimethylamine solution in alcohol was shown to produce not only aminodehalogenation products, but also resulted in nucleophilic substitution of the methoxy groups. The reduction of 6-methoxy-N2,N2,N4,N4-tetramethyl-5-nitroquinoline-2,4-diamine with subsequent methylation gave 6-methoxy-N2,N2,N4,N4,N5,N5-hexamethylquinoline-2,4,5-triamine, a new representative of quinoline proton sponges.

Synthesis and Oxidation of 1,3-Diamino- and 1-Amino-3-azidoindazoles

The amination of 3-amino- and 3-azidoindazoles by hydroxylamine-O-sulfonic acid in an alkaline medium yields previously unreported 1,3-diamino- and 1-amino-3-azidoindazoles. These products undergo slow autoxidation in chloroform solution to give 4-aminobenzo-1,2,3-triazine. The action of formic or acetic acid on 3-amino-1-benzylideneaminoindazole leads to recyclization and formation of 3-amino-2-benzylindazole, which is also formed in the catalytic hydrogenation of 1-benzylamino-3-nitro- and 1-benzylideneamino-3-nitroindazoles.

Synthesis and properties of N-aminoazolinethiones and N-aminoazinethiones 2. Reactions

Literature data on the reactivity of α-mercapto derivatives of N-aminoazoles and N-aminoazines are reviewed.

Methylamino- and dimethylaminoquinolines

Methods for the synthesis and the properties of methylamino- and dimethylaminoquinolines, as well as the interactions between their amino groups and the heteroatom of the ring are reviewed. Particular attention is devoted to the recently obtained 4,5-bis(dimethylamino)-quinolines, which are protonated depending on the substituients primarily at the quinoline ring nitrogen atom or at the peridimethylamino groups. In the latter case these compounds can be characterized as proton sponges. A total of 134 literature references are presented.

1-(NITROSOAMINO)BENZIMIDAZOLES CONTAINING ELECTRON-ACCEPTOR SUBSTITUENTS AT THE AMINE NITROGEN. THEORETICAL AND EXPERIMENTAL INVESTIGATION OF CONFORMATIONAL MOBILITY

The previously unknown 1-(N-nitrosoallylamino)- and 1-(N-nitrosopropargylamino)benzimidazoles have been synthesized and they exist in solution as a mixture of the E- and Z-conformers due to hindered rotation around the N-N(O) bond. The activation energies for the E⇄Z transition in these compounds and for the model N-benzyl analog have been determined by a dynamic 1H NMR method. With a view to studying the effect of a substituent at the amino nitrogen on the E⇄Z isomerization we have carried out 3-21G and 6-31G** type ab initio calculations of the stable conformers of a series of N-nitrosohydrazines.

Some properties of 1-(nitrophenyl)-aminobenzimidazoles

The chemical properties of previously synthesized 1-[2(4)-nitrophenyl/aminobenzimidazoles, in particular, alkylation at the NH group, thiolation, and reduction were studied.