Rearrangement of N-(3-pyridyl)nitramine

Contrary to other N-(pyridyl)nitramines, the title compound cannot be rearranged to 3-amino-2-nitropyridine or other isomers. Hypothetical products of its transformation under influence of concentrated sulphuric acid, viz. 3-hydroxypyridine, 3,3′-azoxypyridine and 3,3′-azopyridine, were obtained from 3-nitro- and 3-aminopyridine in oxidation and reduction reactions. N-(3-Pyridyl)nitramine was prepared and rearranged in concentrated sulphuric acid. 3-Hydroxypyridine and 3,3′-azoxypyridine were isolated from the reaction mixture, other products were identified by the HPLC and GCMS methods. The results indicate that N-(3-pyridyl)hydroxylamine is an intermediate formed from N-(3-pyridyl)nitramine under the influence of concentrated sulphuric acid. The reaction path, leading to the final products, is discussed in context of the mechanism of nitramine rearrangement.     

Reactions of 2-Amino-4-methyl-6-(2-pyridyl)- and 2-Amino-4-methyl-6-phenyl-7,8-dihydroindazolo[4,5-d]thiazoles with Aldehydes

The reaction of 2-amino-4-methyl-6-(2-pyridyl)-7,8-dihydroindazolo[4,5-d]thiazole, obtained by treating 3-methyl-4-oxo-1-(2-pyridyl)-4,5,6,7-tetrahydroindazole with pyridinium bromide perbromide and then with thiourea, and 2-amino-4-methyl-6-phenyl-7,8-dihydroindazolo[4,5-d]thiazole with 4-bromo-, 4-fluoro-, 4-dimethylamino-, 4-methoxy-, 3,4-dimethoxy-, and 3,4-methylenedioxybenzaldehydes, furfural, pyridinecarbaldehyde, and thiophenecarbaldehyde gave the corresponding Schiff bases. The products of the condensation of these aminothiazoles with cinnamaldehyde, 1-(2-pyridyl)- and 4-chloro-1-(2,4-difluorophenyl)-5-formyl-3-methyl-6,7-dihydroindazoles, 2-formyl-dimedone, and 2-formyl-1,3-indanedione were also obtained.     

Boron chelate complexes with some enaminones and diketones containing the pyridine fragment and their mutual transformations in solutions

The interaction of Ph₂BOBu with 4-amino-4-(2-pyridyl)-3-buten-2-one, 3-amino-1-(2-pyridyl)-2-buten-I-one, and 1-(2-pyridyl)butan-1,3-dione was investigated. The 5- or 6-membered chelates withN,O- orN,N-coordination of boron are formed depending on the pyridine-containing ligand structure. These complexes are capable of mutual transformation in solutions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 710–714, March, 1996.     

Synthesis of 2-amino-4-imino-4,5-dihydrothiazoles from N-sulfonyl-α-chloroamidines and thiourea

A number of new and interesting 2-amino-4-(N-substituted)imino-4,5-dihydrothiazoles were synthesized by reacting thiourea (or thiourea hydrochloride) with N-alkyl- or N,N-dialkyl-N′-p-toluenesulfonyl-α-chloroacetamidines, where the N,N-alkyl groups were ethyl, cyclohexyl, benzyl, β-phenethyl, (3,5-dimethyl-1-adamantyl)-methyl, as well as N,N-dimethyl- and N,N-pentamethylene. Reactions of N-alkyl-N-p-toluenesulfonyl-2-chloroacetamidines (substituents being N-ethyl, N-benzyl and N,N-dimethyl) with thiourea hydrochloride in hot 2-propanol furnished 2-amino-4-(p-toluenesulfonyl)imino-4,5-dihydrothiazole (in 51, 60 and 65% yields, respectively) and the corresponding amine hydrochloride. In hot acetone or butanone, the reactions of these N-sulfonyl-2-chloroacetamidines with excess thiourea provided 2-amino-4-N-(alkyl or N,N-dialkyl)imminium-4,5-dihydrothiazole chlorides in 25–80% yield. The by-product from these reactions was p-toluenesulfonamide. The structures of the products were established by chemical transformations and spectral methods (nmr and mass spectra).     

Synthesis of 3-(dibromoacetyl)tropolone and its reactions with thioureas and thioamides

3-(Dibromoacetyl)tropolone ( 3 ) was obtained in the reaction of 3-acetyltropolone with two equimolar amounts of phenyltrimethylammonium tribromide. This tropolone 3 reacted with thiourea, 1-methyl-2-thiourea, and 1-phenyl-2-thiourea to afford N-unsubstituted and N-methyl- or N-phenyl-substituted 3-(2-amino-4-thiazolyl)tropolones. The reactions of 3 with thioacetamide and thiobenzamide gave 3-(2-methyl-and 2-phenyl-4-thiazolyl)tropolones.     

Reinvestigation of the synthesis of 5-arylamino-2-picolines

Reaction of 5-bromo- or 3-bromo-2-methylpyridine with o-nitroaniline gave the corresponding N-[2-methyl-5(or 3)pyridyl]-o-nitroanilines. Reduction to the corresponding amino derivatives and ring closure to 1-[2-methyl-5(or 3)pyridyl]benzotriazole allowed the structures to be confirmed and an earlier literature report to be corrected. Displacement of bromide by anthranilic acid from 5-bromo-2-methylpyridine and decarboxylation gave N-(2-methyl-5-pyridyl)aniline.     

Studies on condensed heterocyclic compounds II.Synthesis and antibacterial activity of 3-(4''''-pyridyl)-6-aroylamino/arylamino-S-triazolo[3,4-b]-1,3,4-thiadiazoles

3-(4′-Pyridyl)-4-amino-5-mercapto-1,2,4-triazole(1)reacted with aroyl isothiocyanates2a-1 to yield twelve novel 3-(4′-pyridyl)-6-aroylamino-S-triazolo[3,4-b]-1,3,4-thiadiazoles,4a-1.Triethylamine was necessary for the condensation of 1 with phenyl isothiocyanate(3)to give 3-(4′-pyridyl)-6-phenylamino-S-triazolo[3,4-b]-1,3,4-thiadiazole(6).The structures were confirmed bythe elemental and spectral analyses.Their antibacterial activity against B.Subtilis,E.Coli,E.aerogenes and S.aureus was observed preliminary.     

On the methylation of 5-(4-alkoxyphenyl)-15-(4-pyridyl)porphyrins

Mixed condensation of 3,3′-diethyl-4,4′-dimethyl-2,2′-dipyrrolylmethane 1 with 4-formylpyridine 2 and 4-alkoxybenzaldehyde 3 in acid medium and subsequent oxidation of the reaction mixture with DDQ gives, among other compounds, title compound 5 . An efficient methylation procedure of the pyridyl group in 5-(4-alkyoxyphenyl)-15-(4-pyridyl)porphyrins is described. Mixed condensation of 1 with N-methyl-4-formylpyridinium salt 9 and 3 yields among other compounds 5-(4-N-methylpyridiniumiodide)porphyrin 10 .     

Synthesis of Pyridyl and N-Methylpyridinium Analogues of Rosamines: Relevance of Solvent and Charge on Their Photophysical Properties

A series of pyridyl analogues of rosamines was prepared by employing two methodologies: (i) the conventional-heating condensation of a pyridinecarboxaldehyde with 3-(diethylamino)phenol in propionic acid, and (ii) the novel ohmic-heating assisted condensation under “on water” conditions, followed by oxidation. The 4-pyridyl substituted rosamine was further converted into the N-methylpyridinium derivative through N-alkylation using methyl iodide. The influence of the position and cationization of the nitrogen atom of the pyridyl ring in the physicochemical properties of fluorophores was investigated by ¹H, ¹³C, ¹⁵N NMR spectral analysis, UV/Vis and fluorescence spectroscopy, single-crystal X-ray diffraction (4-pyridyl and N-methylpyridinium derivatives) and thermal-behavior analysis. Curiously, for ethanolic solutions of 4-pyridyl and N-methylpyridinium derivatives an extinction of color and fluorescence over time was observed. This phenomenon was further studied and the data revealed that it is the result of nucleophilic addition of ethoxide ion to the central 9-position of the xanthene. The kinetics of the process is slower for the 4-pyridyl rosamine, which emphasizes the importance of the charge in the N-methylpyridinium analogue in the reactivity of the molecule towards a nucleophile agent. This phenomenon is reversible, meaning that the compounds can be rapidly recovered by decreasing the pH, opening new avenues in the sensing applications of this class of rosamines.     

A New Route to the Synthesis of 2-Amino-6-(methoxycarbonyl)amino-4-(tetrahydropyridyl)pyrimidine 1-Oxide

A new approach to 2-amino-6-(methoxycarbonyl)amino-4-(1,2,3,6-tetrahydro-1-pyridyl)pyrimidine 1-oxide ( 3 ) is described. Methyl [1-ethoxy-2-(ethoxycarbonyl)-ethylidene]carbamate ( 5 ) reacted with guanidine to the pyrimidinecarbamate 6 , which was successively transformed into methyl 2-amino-6-(p-tolyslulfonyl)oxy-4-pyrimidinecarbamate ( 8 ). Oxidation of 8 led to the corresponding pyrimidine N-oxide 9 , a useful starting material to 3 .     

On the preparation of substituted 4H- 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

The reaction of benzoyl isothiocyanates and methoxycarbonyl isothiocyanate with 4-amino-4,5-dihydro-3-(methylthio)-1,2,4-triazin-5-ones in acetonitrile gave several substituted 4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones VIa-h instead of the expected thioureas. In addition, benzoyl isothiocyanate reacted with 4-amino-3-(methylthio)-5-(trifluoromethyl)-4H-1,2,4-triazole to give the benzoyl thiourea IX and with 4-amino-3-mercapto-5-(trifluoromethyl)-4H-1,2,4-triazole to give the bicyclic compound N-[3-(trifluoromethyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazol-6-yl]benzamide IX .     

Fused s-triazino heterocycles. XV. 13H-4,6,7,13a,13c-pentaazabenzo[hi]chrysene, 13H-4,7,13a,13c-tetraazabenzo[hi]chrysene,and 7H-3,7,10,10b-tetraazacyclohepta[de]naphthalene,three new ring systems

The reaction of N-cyano-N′-(6-amino-2-pyridyl)acetamidine ( 5a ) and homophthalic anhydride followed by ring closure of the 2-[2-(carboxymethyl)phenyl]-5-methyl-1,3,4,6,9b-pentaazaphenalene intermediate ( 4a ) gave 5-methyl-13-oxo-13H-4,6,7,13a,13c-pentaazabenzo[hi]chrysene ( 8a ). An analogous series starting with 3-N-(6-amino-2-pyridyl)amino-2-cyano-2-butenenitrile ( 5b ) in place of 5a gave in two steps 5-methyl-13-oxo-13-H-4,7,13a,13c-tetraazabenzo[hi]chrysene-6-carbonitrile ( 8b ). Elemental analysis, ir and pmr spectra of 8a , 8b and several new model compounds aided in confirming the structures of 8a and 8b. The synthesis of one of these model compounds for 5b and phenylacetic anhydride led surprisingly to 2-methyl-9-phenyl-7H-3,7,-10,10b-tetraazacyclohepta[de]naphthalene ( 10 ) in addition to the expected 2-benzyl-4-cyano-5-methyl-1,3,-6,9b-tetraazaphenalene ( 7b ).     

Synthesis of some substituted pyridylsydnones

Synthesis of the I-oxide ( 2 ) of the photochromic N-(3-pyridyl) sydnone ( 1 ), of N-(5-bromo-3-pyridyl) sydnone ( 3 ), and the I-oxide ( 4 ) of 3 were undertaken in order to study the effect on photochromism exerted by substituents on the pyridine ring. Compounds 2 and 3 were prepared via the corresponding aminopyridines and N-pyridylglycines by the general procedure used earlier to prepare 1 . The required amines, 3-aminopyridine I-oxide and 3-amino-5-bromopyridine, were obtained by Hofmann rearrangement of the corresponding amides. An excellent preparation of 5-bromonicotinamide was developed involving bromination in thionyl chloride followed by reaction of the bromoacid chloride with ammonia in chloroform. Proof of structure for 2 and 3 was accomplished by acid hydrolysis to the corresponding hydrazines, which were isolated, respectively, as acetophenone 3-pyridylhydrazone I-oxide and as 5-bromo-3-pyridylhydrazine hydrochloride. These products were identical with samples prepared by reduction of the respective diazotized amines. Sydnone 4 eluded preparation by this general procedure. 3-Amino-5-bromopyridine I-oxide was prepared conveniently from 5-bromonicotinamide but attempts to prepare the corresponding glycine by catalytic hydrogenation of a mixture of the amine and butyl glyoxylate afforded, in acid solution, N-(3-pyridyl)glycine and, in neutral or alkaline solution, the I-oxide of N-(3-pyridyl)glycine. Both products resulted from the reductive cleavage of the bromine atom. Neither 2 nor 3 was photochromic.     

N-乙氧羰基-N'-3-吡啶基硫脲的合成及其超分子晶体结构

以N,N,N',N'-四甲基乙二胺(TMEDA)为催化剂, 通过氯甲酸乙酯与硫氰酸钾反应合成了中间体乙氧羰基异硫氰酸酯, 后者不需分离直接与3-氨基吡啶反应, 得到N-乙氧羰基-N'-3-吡啶基硫脲. 该产物用EA, IR, ¹H NMR进行了表征, 经X射线单晶衍射法确定了其单晶结构, 晶体结构表明, 晶体属于单斜晶系, P2(1)/c空间群, 晶胞参数: a＝1.0333(6) nm, b＝0.7118(4) nm, c＝1.5160(8) nm, α＝γ＝90.00°, β＝98.517(8)°, V＝1.1028(10) nm³, Z＝4. 晶体中硫脲分子通过分子间氢键的相互作用形成了一维链状超分子结构, 由于范德华力作用形成沿b轴延伸的层状结构.     

1H NMR studies of intramolecular hydrogen bonding in N-(pyridyl)amides of 6-methylpicolinic acid N-oxide

The ¹H NMR spectra of seven N-(pyridyl)amides of 6-methylpicolinic acid N-oxide in chloroform were obtained. The influence on the chemical shifts of the N? H protons of temperature, concentration and the CH₃ substituent in the pyridine ring was studied. The N? H protons were found to be shifted to low fields (～14 ppm) owing to the formation of strong intramolecular hydrogen bonding. The influence of the pyridine ring on the chemical shift of the N? H proton is comparable with the inductive effect of the p-nitrophenyl group. The hindered rotation around the N-pyridyl bond of N-(α-pyridyl)amides of 6-methylpicolinic acid in solution is discussed.     

Reaction between benzyllithium and 2-ethylpyridine: chiral crystals of a 1-(2-pyridyl)ethyllithium complex versus formation of lithium 4-benzyl-2-ethyl-1,4-dihydropyridinide

Abstract  

The reaction between benzyllithium and prochiral 2-ethylpyridine in tetrahydrofuran has been studied. In the presence of N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDTA), it was found that 1-(2-pyridyl)ethyllithium was formed as a PMDTA complex. This complex is mononuclear, with lithium coordinated to the pyridyl nitrogen atom only; there are no short lithium–carbon distances and the structure approaches that of an enamide rather than a carbanion. The complex undergoes spontaneous resolution and forms chiral crystals with two molecules in the asymmetric unit; the two molecules have different configurations at the chirogenic pyridyl nitrogen atoms but share the same chiral conformation of the chelate ring systems. Reaction between benzyllithium and 2-ethylpyridine in tetrahydrofuran in the absence of PMDTA was found to give a high proportion of lithium 4-benzyl-2-ethyl-1,4-dihydropyridinide, and crystals of a dinuclear complex displaying tetrahydrofuran ligands and co-crystallised n-hexane molecules were isolated.     

Fused polycyclic nitrogen-containing heterocycles

The condensation of methyl phenylchloropyruvate with 1-phenyl-3-(2-pyridyl)thiourea and its 3-and 4-picolyl homologs affords the corresponding 4-hydroxythiazolidines, which react with o-phenylenediamine to give one of two possible thiazolo[3,4-a]quinoxalines containing the pyridyl-or picolylimine substituents at position 1. 3a-Hydroxy-3-phenylimino-1-(2-pyridyl)thiazolo[3,4-a]quinoxalin-4-(3H,5H)-one, which is a covalent hydrate of the final product, was isolated as an intermediate in this reaction.     

Synthesis of isonipecotinoyl analogues of aminopterin and folic acid

The preparation of isonipecotinoyl analogues of aminopterin and methotrexate is described. Condensation of diethyl N-isonipecotinoyl-L-glutamate 4 with 2-amino-5-bromomethyl-3-cyanopyrazine 5 afforded diethyl N-(N-[(2-amino-3-cyanopyrazin-5-yl)methyl]isonipecotinoyl)-L-glutamate 6 . Cyclisation of 6 with guanidine followed by blocking group hydrolysis afforded N-([N-(2,4-diaminopteridin-6-yl)methyl]isonipecotinoyl)-L-glutamic acid 8 . Coupling of N-(2-amino-4(3H)ioxopteridin-6-yl]methyl)isonipecotinic acid 11 with diethyl L-glutamate gave diethyl N-[(N-[2-amino-4(3H)-oxopteridin-6-yl]methyl)isonipecotinoyl]-L-glutamate 12 . Blocking group hydrolysis afforded N-[(N-[2-amino-4(3H)-oxopteridin-6-yl]methyl)isonipecotinoyl]-L-glutamic acid 13 .     

Synthesis of 1-(2-ethyl-3-indolyl)-1-(3-pyridyl)ethylene and related ellipticine analogues

Indole, 2-methylindole, and 3-etliylindole have been condensed with acetyl- and propionylpyridine, respectively. When propionylpyridine was used as the reactant, the product always was a 1-(pyridyl)-1-indoly[propylene. Condensation of 2-substituted indoles with 3-acetylpyridine gave similar products, whereas a similar condensation with 4-acetylpyridine gave 1,2-bis(3-indolyl)-1-(4-pyridyl)ethanes (e.g. 7a ). Condensation of unsubstituted indole with 3-or 4-acetylpyridine respectively, gave 1,1-bis(3-indolyl)-1-(pyridyl)ethanes (e.g. 6c ).     

Reaction of N-(4-pyridylmethyl)benzamide N-oxides with ethyl cyanoacetate in the presence of acetic anhydride

Reaction of N-(4-pyridylmethyl)benzamide N-oxides 2a-f with ethyl cyanoacetate in the presence of acetic anhydride yield dimerization compounds 3a-f and (E)-ethyl 2-cyano-3-(4-pyridyl)-3(benzoylamino)acrylates 4a-f , which react with hydrazine to give 4-cyano-3-(4-pyridyl)-3-pyrazolin-5-one 9 and the corresponding benzamides 10a-f .