A study of nitrogen- and sulfur- containing heterocycles

The reaction of 3-amino-6-chloro-2-mercaptopyridine with phenacyl halides has been studied, and a number of 3-aryl-7-chloro-2H-pyrido-[2,3-b]-1,4-thiazines have been synthesized. Two types of intermediate compounds have been isolated: 2-amino-6-chloro-2-phenacyl-thiopyridines and 3-aryl-7-chloro-3-hydroxy-1,2-dihydropyrido[2,3-b]-1,4-thiazines.     

A study of nitrogen- and sulfur- containing heterocycles

The reaction of 3-amino-6-chloro-2-mercaptopyridine with phenacyl halides has been studied, and a number of 3-aryl-7-chloro-2H-pyrido-[2,3-b]-1,4-thiazines have been synthesized. Two types of intermediate compounds have been isolated: 2-amino-6-chloro-2-phenacyl-thiopyridines and 3-aryl-7-chloro-3-hydroxy-1,2-dihydropyrido[2,3-b]-1,4-thiazines.For part VI, see [3].     

Synthesis of 1,2-diazepino[3,4-b]quinoxalines and pyrido[3′,4′:9,8][1,5,6]oxadiazonino[3,4-b]quinoxalines via a 1,3-dipolar cycloaddition reaction

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 8 with furfural, 3-methyl-2-thiophene-carbaldehyde, 2-pyrrolecarbaldehyde, 4-pyridinecarbaldehyde and pyridoxal hydrochloride gave 6-chloro-2-[2-(2-furylmethylene)-1-methylhydrazino]quinoxaline 4-oxide 5a , 6-chloro-2-[1-methyl-2-(3-methyl-2-thienyl-methylene)hydrazino]quinoxaline 4-oxide 5b , 6-chloro-2-[1-methyl-2-(2-pyrrolylmethylene)hydrazino]quinoxa-line 4-oxide 5c , 6-chloro-2-[1-methyl-2-(4-pyridylmethylene)hydrazino]quinoxaline 4-oxide 5d and 6-chloro-2-[2-(3-hydroxy-5-hydroxymethyl-2-methyl-4-pyridylmethylene)-1-methylhydrazino]quinoxalme 4-oxide 5e , respectively. The reaction of compound 5a or 5b with 2-chloroacrylonitrile afforded 8-chloro-3-(2-furyl)-4-hydroxy-1-methyl-2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxaline-5-carbonitrile 6a or 8-chloro-4-hydroxy-1-methyl-3-(3-methyl-2-thienyl)-2,3-dihydro-1H-1,2-diazepino[3,4-b]quinoxaline-5-carbonitrile 6b , respectively, while the reaction of compound 5e with 2-chloroacrylonitrile furnished 11-chloro-7,13-dihydro-4-hydroxy-methyl-5,14-methano-1,7-dimethyl-16-oxopyrido[3′,4′:9,8][1,5,6]oxadiazonino[3,4-b]quinoxaline 7.     

Synthesis of 2-(1,5,9-Triazabicyclo[7.3.1]tridec-10-en-5-yl)-4-methylthiobutanoic Acid Derivatives

Reactions of 1,3-bis(3-chloro-2-hydroxypropyl)uracil, 1,3-bis(3-chloro-2-hydroxypropyl)-6-methyluracil, 1,3-bis(3-chloro-2-hydroxypropyl)-5-hydroxy-6-methyluracil, and 1,3-bis(3-chloro-2-hydroxypropyl)-5-fluorouracil with 2-amino-4-methylthiobutanoic acid (methionine) were studied for the first time.     

Formation of benzynes from 2,6-dihaloaryllithiums: mechanistic basis of the regioselectivity

The key elimination step for the formation of 3-chloro- and 3-fluorobenzyne from 2-chloro-6-fluorophenyllithium displays a pronounced solvent-dependent regioselectivity. 6Li and 13C NMR spectroscopic studies on 2-chloro-6-fluorophenyllithium reveal a single monomeric aryllithium, suggested by DFT computational studies to be a trisolvate. Rate studies indicate that the elimination of LiCl and LiF proceeds via trisolvated and disolvated monomers, respectively.     

Synthesis of isothiocoumarin derivatives

A method was developed for the synthesis of 1-oxo-1H-isothiochromenes from 2-benzofuran-1(3H)-one (phthalide). 3-Bromo-6-chloro- and 3,6-dibromo-2-benzofuran-1(3H)-ones were prepared by the bromination of 6-chloro- and 6-bromo-2-benzofuran-1(3H)-ones and were converted by hydrolysis into 5-chloro- or 5-bromo-2-formylbenzoic acids. The condensation of these acids with rhodanine followed by recyclization gave 7-chloro- and 7-bromo-1-oxo-1H-isothiochromene-3-carboxylic acids.     

Synthesis and calcium channel antagonist activity of new symmetrical and asymmetrical 4-[2-chloro-2-(4-chloro-6-methyl-2-oxo-2H-pyran-3-yl)vinyl]-substituted 1,4-dihydropyridines

New symmetrical 4-[2-chloro-2-(4-chloro-6-methyl-2-oxo-2H-pyran-3-yl)vinyl]-substituted 1,4-di-hydropyridines were synthesized in moderate to good yields via the modified Hantzsch reaction of β-dicarbonyl compounds with (Z)-3-chloro-3-(4-chloro-6-methyl-2-oxo-2H-pyran-3-yl)acrolein in the presence of an excess amount of NH₄OAc. Also, the reaction of β-dicarbonyl compounds with (Z)-3-chloro-3-(4-chloro-6-methyl-2-oxo-2H-pyran-3-yl)acrolein in the presence of enamino esters and ketones was performed, and asymmetrical 4-[2-chloro-2-(4-chloro-6-methyl-2-oxo-2H-pyran-3-yl)vinyl]-substituted 1,4-dihydropyridines were obtained in moderate to good yields at room temperature. The calcium channel blocking activity of these compounds was assessed. They demonstrated moderate to weak effects, although one compound had a comparable effect (IC₅₀ =1.40×10⁻⁷ M) with respect to the reference drug Nifedipine.     

Unusual reaction of 4-[(3-carboxypropyl)amino]-6-chloro-5-nitrobenzofuroxan with 3-aminopropane-1,2-diol 1,2-dinitrate

Reaction of 4-[(3-carboxypropyl)amino]-6-chloro-5-nitrobenzofuroxan with 3-aminopropane-1,2-diol 1,2-dinitrate yielded 6-chloro-5-nitro-4-(2-oxopyrrolidin-1-yl)benzofuroxan instead of the expected 6-chloro-5-nitrobenzofuroxan amino derivative.     

Nucleophilic substitution by 3-amino-1,2-propanediol in nitropyrazines and nitroquinoxalines

Treatment of 2-chloro-3-nitropyrazine and 2-chloro-5-nitropyrazine with 3-amino-1, 2-propanediol affords products derived from displacement of chloride, while similar reaction of methyl 3-nitropyrazinoate and 2-chloro-3-nitroquinoxaline gives clean nitro group replacement. Analogous reaction of methyl 6-chloro-3-nitropyrazinoate affords a mixture containing products derived from competitive displacement of chloride and nitrite.     

3-取代苄氧基-6-(取代-1H-吡唑-1-基)哒嗪的合成与生物活性

3-氯-6-肼基哒嗪分别与乙酰丙酮和3-二甲胺基丙烯醛反应, 合成了中间体3-氯-6-(3,5-二甲基-1H-吡唑-1-基)哒嗪(2)和3-氯-6-(1H-吡唑-1-基)哒嗪(4), 它们与多种取代苄醇反应, 得到了一系列未见报道的3-取代苄氧基-6-(取代-1H-吡唑-1-基)哒嗪, 其结构均经1H NMR, IR和元素分析确证. 初步的生物活性测试结果表明, 所合成的化合物对油菜和稗草均具有一定的抑制作用.     

Synthesis of mesoionic triazolo[4,3-a]quinoxalines

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 1 or 6-chloro-2-(1-methylhydrazino)-quinoxaline 5 with phenyl isothiocyanate under reflux in N,N-dimethylformamide gave 7-chloro-3-methyl-1,2,4-triazolo[4,3-a]quinoxalin-3-ium-1-thioate 4 , which was also obtained by refluxing of 6-chloro-2-[1-methyl-2-(N-phenylthiocarbamoyl)hydrazino]quinoxaline 4-oxide 2b or 6-chloro-2-[1-methyl-2-(N-phenylthiocarbamoyl)hydrazino]quinoxaline 6 in N,N-dimethylformamide.     

Unusual Acetylation of 2-Methyl-1-phenylsulfonylindole

Acetylation of 2-methyl-1-phenylsulfonylindole with an excess of aluminium chloride and acetic anhydride afforded exclusively 6-acetyl-3-chloro-2-methylindole and 6-acetyl-3-chloro-2-methyl-1-phenylsulfonylindole.     

Tautomeric structure of 1-methyldihydropyridazino-[3,4-b]quinoxalines in solution

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 1 with ethyl 2-ethoxymethylene-2-cyano-acetate or ethoxymethylenemalononitrile gave 6-chloro-2-[2-(2-cyano-2-ethoxycarbonylvinyl)-1-methylhy-drazino]quinoxaline 4-oxide 3a or 6-chloro-2-[2-(2,2-dicyanovinyl)-1-methylhydrazino]quinoxaline 3b , respectively. The reaction of 3a with a base afforded 7-chloro-1-methyl-1,5-dihydropyridazino[3,4-b]quinoxaline 4 . From the NOE spectral data, the 1-methyldihydropyridazino[3,4-b]quinoxalines 2a, 2b and 4 were found to exist as the 1,5-dihydro form in a dimethyl sulfoxide or trifluoroacetic acid/dimethyl sulfoxide solution.     

Preparation of delta-Chloro-alpha-allenyl Ketones by Acylation of 3-Buten-1-ynes

AlCl(3)-mediated acylation of 3-buten-1-yne derivatives with acyl chlorides yields a mixture of 5-chloro-2,3-pentadienones and 3-chloro-2,4-pentadienones. The proportion of allenyl ketones vs conjugated dienic ketones depends on the substitution pattern of the starting enyne. Acylation of 5-acetoxy-3-buten-1-ynes leads to the corresponding allenyl ketones (6-acetoxy-5-chloro-2,3-pentadienones).     

Reaction of 6-chloro-2-[1-methyl-2-(N-methylthiocarbamoyl)]-hydrazinoquinoxaline 4-oxide with dimethyl acetylenedicarboxylate

The reaction of 6-chloro-2-(1-methylhydrazino)quinoxaline 4-oxide 4a with methyl or phenyl isothiocyanate gave 6-chloro-2-[1-methyl-2-(N-methylthiocarbamoyl)hydrazino]quinoxaline 4-oxide 7a or 6-chloro-2-[1-methyl-2-(N-phenylthiocarbamoyl)hydrazino]quinoxaline 4-oxide 7b , respectively, whose reaction with dimethyl acetylenedicarboxylate afforded 6-chloro-2-[N-methyl-N-(5-methoxycarbonylmethylene-3-methyl-4-oxo-2-thioxoimidazolidin-1-yl)]aminoquinoxaline 4-oxide 8a or 6-chloro-2-[N-methyl-N-(5-methoxycarbonylmethylene-4-oxo-3-phenyl-2-thioxoimidazolidin-1-yl)]aminoquinoxaline 4-oxide 8b , respectively.     

Control of electron demand in the cycloadditions of 2(H)-1,4-oxazin-2-ones

3-Methoxy-5-chloro-6-methyl-2(H)-1,4-oxazin-2-one 4, 3-methoxy-5-chloro-6-phenyl-2(H)-1,4-oxazin-2-one 5, 3-phenylsulfenyl-5-chloro-6-methyl-2(H)-1,4-oxazin-2-one 6, and 3-phenylsulfenyl-5-chloro-6-phenyl-2(H)-1,4-oxazin-2-one 7, are ambident dienes and undergo Diels-Alder cycloadditions with electron neutral, rich and deficient dienophiles.     

Reactions of 3-chloro-6-hydrazinopyridazine with michael-retro-michael reagents

Although pyrazole formation results from treatment of 3-chloro-6-hydrazinopyridazine ( 2 ) with both ethoxymethylenemalononitrile and ethyl (ethoxymethylene)cyanoacetate, 6-chlorotriazolo[4,3-b]pyridazine ( 5 ) was produced (75% yield) when 2 was treated with diethyl ethoxymethylenemalonate. Treatment of 2 with diethyl acetylmalonate ( 8 ) gave both 6-chloro-3-methyltriazolo[4,3-b]pyridazine ( 10 ) and 5-hydroxy-3-methyl-1-(6-chloro-3-pyridazinyl)-1H-pyrazole-4-carboxylic acid ethyl ester ( 12 ). Pyrazole 12 was initially isolated as a salt of triazolopyridazine 10 .     

Regioselective synthesis of 4-chlorophenols, 10-chloro-7-hydroxy-6H-benzo[c]chromen-6-ones, and 4-chloro-1-hydroxy-9H-fluoren-9-ones based on [3+3] cyclizations of 1,3-bis(silyloxy)-1,3-dienes with 2-chloro-3-silyloxy-2-en-1-ones

A variety of 4-chlorophenols, 10-chloro-7-hydroxy-6H-benzo[c]chromen-6-ones, and 4-chloro-1-hydroxy-9H-fluoren-9-ones were prepared by formal [3+3] cyclizations of 1,3-bis(silyloxy)-1,3-dienes with 2-chloro-3-(silyloxy)alk-2-en-1-ones.     

Reactions of Polyfluorinated 3-Substituted 2,4-Cyclohexadienones with Alkynes

Reactions of 2,3,4,5,6-pentafluoro-6-chloro-2,4-cyclohexadienone with anthranylic acid, 2,6-dichloro- and 2,6-dimethylaniline, diethylamine, sodium azide, and also the reaction of 6-phenyl-3-pentafluorophenoxy-2,4,5,6-tetrafluoro-2,4-cyclohexadienone with methanol afford 3-substituted 2,4,5,6-tetrafluoro-2,4-cyclohexadienones. The 3-methoxy-2,4,5,6-tetrafluoro-6-chloro-2,4-cyclohexadienone and 3-methoxy-6-phenyl-2,4,5,6-tetrafluoro-2,4-cyclohexadienone form cycloadducts with 1-hexyne and propargyl alcohol that under treatment with propyl alcohol in the presence of potassium carbonate undergo ring cleavage to furnish propyl arylfluorochloroacetates and diarylacetates. The reaction between 3-azido-2,4,5,6-tetrafluoro-6-chloro-2,4-cyclohexadienone and phenylacetylene gives rise to 4-oxo-2-phenyl-3,5,6,7-tetrafluoro-5-chlorobicyclo[4.1.0]hept-2-ene-7-carbonitrile.     

Chlorination features of 1,5-dinitro-3-azabicyclo[3.3.1]non-6-enes

The electrophilic chlorine addition to 3-substituted 1,5-dinitro-3-azabicyclo[3.3.1]-non-6-enes in the tetrachloromethane is accompanied at an intramolecular 3,7-cyclization giving 6-chloro-3-R-1,5-dinitro-3-azoniatricyclo[3.3.1.03,7]nonane chlorides. The reaction of the tricyclic quaternary ammonium salts with sodium methoxide leads to the formation of dealkylated and dehydrohalogenated products, 3-substituted 8-chloro-1,5-dinitro-3-azabicyclo[3.3.1]non-6-enes, bicyclic products with a halogen atom in an allyl position with respect to the double bond.