Nucleophilic Substitution Of Hydrogen Atom Research Articles

Two-step synthesis of indeno[1,2-b]furazanopyrazines through combination of the SNH and Heck reactions

Enamines generated in situ from aliphatic amines and acetone react with 5-(2-bromophenyl)furazano[3,4-b]pyrazines via the nucleophilic substitution of hydrogen atom of the pyrazine ring. A representative of 9H-indeno[1,2-b]furazanopyrazin-9-ylidene ring system has been accessed by exploiting the intramolecular Heck cyclization of the obtained SNH-product. Several compounds derived from the SNH reaction, namely, N-alkyl-1-[6-(2-bromophenyl)furazano[ 3,4-b]pyrazin-5-yl]prop-1-en-2-amines, proved to exhibit a bacteriostatic activity in vitro against Mycobacterium tuberculosis H37Rv

Nucleophilic Substitution of Hydrogen Atom in Initially Inactivated Pyrrole Ring.

It has been found that 1-dialkylamino-8-(pyrrolyl-1)naphthalenes 1 and 6, upon treatment with an equimolar amount of HBF4 under ambient conditions, produce 1-dialkylammonium salts which are transformed into 7,7-dialkyl-7 H-pyrrolo[1,2- a]perimidine-7-ium tetrafluoroborates 5 and 7, respectively. The reaction proceeds in a highly selective manner and represents the first case of nucleophilic substitution of hydrogen in the initially inactivated pyrrole ring. The scope and limitations of the transformation, apparently operating due to the joint action of the "proximity effect" and proton catalysis, are outlined.

OXIDATIVE S N H AMIDATION OF ACRIDINE AND TAUTOMERISM OF N -(ACRIDIN-9-YL)BENZAMIDES

Direct oxidative nucleophilic substitution of hydrogen atom in acridine molecule was used to synthesize 9-acylaminoacridines. The prototropic amine-imine tautomerism of these compounds was studied. How to Cite Demidov, O. P.; Borovlev, I. V.; Amangasieva, G. A.; Avakyan, E. K. Chem. Heterocycl. Compd. 2016 , 52 , 104. [ Khim. Geterotsikl. Soedin. 2016 , 52 , 104.] For this article in the English edition see DOI 10.1007/s10593-016-1841-7

Oxidative SNH amidation of acridine and tautomerism of N-(acridin-9-yl)benzamides

Direct oxidative nucleophilic substitution of hydrogen atom in acridine molecule was used to synthesize 9-acylaminoacridines. The prototropic amine-imine tautomerism of these compounds was studied.

Synthesis and spectroanalytical studies of a new heterocyclic acid–base indicator

New purple dyes of the imidazopyridine series were synthesized by the reaction of 6-chloro-3-nitroimidazo[1,2-a]pyridine with arylacetonitriles in basic MeOH solution via nucleophilic substitution of hydrogen atom. The obtained 2-aryl-2-[6-chloro-3-(hydroxyimino) imidazo[1,2-a]pyridin-2(3H)-ylidene)]acetonitriles were further converted to new 8-chloropyrido[2',1':2,3]imidazo[4,5-b]-quinoline-12-carbonitriles. The solution of 2-[6-chloro-3-(hydroxyimino)imidazo[1,2-a]pyridin-2(3H)-ylidene)]-2-(4-methylphenyl)acetonitrile undergoes a reproducible color change due to the addition of acid or base. A UV-Vis spectroscopic characterization and acid–base equilibrium study of this dye was carried out with the view of its possible use as an indicator. The results show that this dye is an amphoteric substance with two ionization constants K a1 and K a2 indicative of weak basic and acidic properties. The pK a1 and pK a2 values in aqueous solution determined by spectrophotometric method are 2.43 and 9.73, respectively. A comparison was made with existing acid–base indicators effective over the same pH range.

Bipyridines. XIX. Synthesis of some novel 2,7,9,10‐Tetraazaphenanthrene derivatives

Abstract[4,4′‐Bipyridine]‐3,3′‐diamine (1) reacts with HNO2 in H2SO4 to form 2,7,9,10‐tetraazaphenanthrene (2) and 9H‐pyrrolo[2,3‐c:5,4‐c′]dipyridine (3) instead of expected bipyridinediol 4 or furodipyridine 5. On the other hand, diazotization of 1 in hydrohalogenic acids leads to novel 3‐halogeno‐2,7,9,10‐tetraazaphenanthrenes 10 or 11 and this reaction represents a new type of regioselective nucleophilic substitution of hydrogen atom in heteroaromatic species. The proposed pathway of reactions was supported by an experiment with the hypothetic intermediate, i.e. 2,7,9,10‐tetraazaphenanthrene‐9‐imine (8), which was obtained on independent route.