Folate antagonists. 5. Antimalarial and antibacterial effects of 2,4-diamino-6-(aryloxy and aralkoxy)quinazoline antimetabolites

2 Various4-diamino-6-(phenoxy, naphthyloxy, and phenalkoxy)quinazolines (VIII, XIV) were synthesized for antimalarial and antibacterial evaluation. Treatment of the anion of the requisite phenol or naphthol with 5-chloro-2-nitrobenzonitrile (V) gave the corresponding 2-nitro-5-(phenoxy and naphthyloxy)benzonitriles (VI) (33–78%). Alternatively, alkylation of 5-hydroxy-2-nitrobenzaldehyde (IX) with the appropriate phenalkyl halide afforded the 2-nitro-5-(phenalkoxy)benzaldehydes (X) (27–62%), which were converted to the 2-nitro-5-(phenalkoxy)benzonitriles (XII) via the intermediate oximes XI (62–87% overall). Reduction of the 2-nitrobenzonitriles (VI, XII) with stannous chloride-hydrochloric acid provided the corresponding 2-amino-5-(phenoxy, naphthyloxy, and phenalkoxy)benzonitriles (VII, XIII) (30–83%), which upon cyclization with chloroformamidine hydrochloride gave the 2,4-diaminoquinazolines VIII and XIV (12–85%). Against Plasmodium berghei in mice, eleven compounds were active orally at doses ranging from 6.3 to 174 mg./kg./day for 6 days, while seven substances displayed activity subcutaneously following single doses of 40–640 mg./kg. Fifteen compounds exhibited in vitro antibacterial activity against Streptococcus faecalis (MGH-2), normal (UC-76) and drug-resistant (S18713) Staphylococcus aureus, Escherichia coli (Vogel), and Shigella sonnei (C-10) with MIC's ranging from < 0.25 to 20 μg./ml. (gradient plate). Data on the inhibitory effects of representative compounds against Streptococcus faecalis R (S. faecium var. durans), S. faecalis A (amino-pterin, methotrexate-resistant), and Lactobacillus plantarum are presented, and overall structure-activity relationships are discussed.     

Folate antagonists. 16. Antimalarial and antibacterial effects of 2,4-diamino-6-[(heterocyclic)thio,sulfinyl, and sulfonyl]quinazolines

The reaction of 5-chloro-2-nitrobenzonitrile with a variety of mercaptoheterocycles provided the corresponding 2-nitro-5-[(heterocyclic)thio]benzonitriles. Reduction to the amine followed by cyclization with chloroformamidine hydrochloride afforded a series of 2,4-diamino-6-[(hetero-cyclic)thio]quinazolines. Bromination, oxidation, and amidine formation were accomplished with 2,4-diamino-6-[(4-phenyl-2-thiazolyl)thio]quinazoline (23) to provide additional analogs. Several of these compounds exhibited suppressive antimalarial activity against drug-sensitive lines of Plasmodium berghei in mice.     

Syntheses of various 5-(bromoaryl)-substituted uracils

The Suzuki Pd(0)-catalyzed coupling between arylboronic acids and aryl bromides or iodides in weakly alkaline medium, previously further developed by us, has been used for regioselective preparation of 5-(2′-bromo-5′-furyl)-, 5-(2′-bromo-4′-furyl)-, 5-(2′-bromo-5′-thienyl)-, 5-(2′-bromo-4′-thienyl)-, 5-(4′-bromo-2′-thiazolyl)-, 5-(3′-bromophenyl)-, 5-(6′-bromo-2′-pyridyl)- and 5-(4′-bromo-2′-pyrimidyl)-substituted 2,4-di-t-butoxypyrimidines. In the coupling between 2,4-di-t-butoxy-5-pyrimidineboronic acid and the nine different aryl dibromides that were tried as coupling partners, only the 2,4- and 2,5-dibromothiazoles did not give satisfactory yields, 15% and 0%, respectively. The other seven aryl dibromides gave the desired 5-(bromoaryl)-2,4-di-t-butoxypyrimidines in 58-89% yield. Attempts to synthesise 2,4-di-t-butoxy-5-(2′-bromo-4′-thienyl)pyrimidine from 2-bromo-4-iodothiophene failed. Dealkylation of the 5-(bromoaryl)-2,4-di-t-butoxypyrimidines in 2.5 M hydrochloric acid gave the corresponding 5-(bromoaryl)uracils in almost quantitative yields.     

Syntheses of various 5-(3′-substituted phenyl)uracils

The Suzuki Pd(0)-catalysed coupling between arylboronic acids and aryl bromides or iodides in weakly alkaline medium has been used for the preparation of 5-(3′-chlorophenyl)-, 5-(3′-iodophenyl)-, 5-(3′-aminophenyl)-, 5-(3′-azidophenyl)-, 5-(3′-methylthiophenyl)- and 5-(3′-styryl)-substituted 2,4-di-t-butoxypyrimidines. In the coupling between 2,4 di-t-butoxy-5-pyrimidineboronic acid and the six different aryl halides that were used as coupling partners, only 1-azido-3-bromobenzene did not give satisfactory yields, 18%. The other five aryl halides gave the desired 5-(3′-substituted phenyl)-2,4-di-r-butoxypyrimidines in 41–92% yield. Dealkylation of these five 5-(3′-substituted phenyl)-2,4-di-t-butoxypyrimidines in 2.5M hydrochloric acid gave the corresponding 5-(bromoaryl)uracils in almost quantitative yields. 5-(3′-Azidophenyl)uracil was prepared in 43% yield directly from 5-(3′-aminophenyl)-2,4-di-r-butoxypyrimidine.     

Synthesis of 5-substituted benzyl-2,4-diamino pyrimidine derivatives as c-Fms kinase inhibitors

<正>A serials of novel 5-substituted benzyl-2,4-diamino pyrimidine derivatives have been synthesized and evaluated as inhibitors of c-Fms kinase by the standard MTT method.The results showed that compound 15,5-[3-methoxy-4-(pyridine-3-yl)benzyl]-2,4-diamino pyrimidine,had an IC_(50) of 1.45μmol/L in inhibiting the proliferation of M-CSF-dependent myeloid leukemia cells in mice (NFS-60),which was similar with GW2580,a selective inhibitor of c-Fms kinase.     

Synthesis of 4-(pyrazol-5-yl)-1,2,4-triazole-3-thiones

Condensation of pyrazolyl isothiocyanates 2 with N-substituted hydrazines provided the 2-methyl/phenyl-4-(pyrazol-5-yl)thiosemicarbazides 3 . Cyclization of 3 with formic acid-acetic anhydride or with triethyl orthoacetate-acetic anhydride provided 4-(pyrazol-5-yl)-l,2,4-triazole-3-thiones 4a-f and 5-methyl-4-(pyrazol-5-yl)-1,2,4-triazole-3-thiones 4g-I respectively.     

3-Aryl- or 3-(trans-4-alkylcyclohexyl)- 6-arylcyclohex-2-enones: synthesis,transformations and mesomorphic properties

The synthesis and chemical transformations of 3-aryl- or 3-(trans-4-alkylcyclohexyl)- 6-arylcyclohex-2-enones into liquid crystalline compounds are discussed. These 3,6-disubstituted cyclohex-2-enones were prepared by the condensation of appropriate Mannich salts or trans-4-alkylcyclohexyl 2-bromoethyl ketones with 4-substituted benzyl methyl ketones.     

Electrophilic reaction of nitric oxide with Wittig reagents

Reaction of nitric oxide (NO) with p-substituted benzyl triphenylphosphonium chlorides or bromides (Wittig reagents) in CH₂Cl₂ under argon undergoes electrophilic attack of NO on the carbon center of phosphonium ylides, producing benzonitriles.     

Reaction of 9-substituted 1-aminoadenine with hydrazine

Reaction of 9-substituted (methyl or benzyl) 1-aminoadenines 1 with hydrazine afforded 9-substituted 6-hydrazinopurines 2 and 1-substituted 5-ammo-4-(4-amino-1,2,4-triazol-3-yl)imidazole ( 4 ). The product ratio of 2 to 4 rose with increasing amounts of methanol used as the solvent. When the same reaction was carried out using 1,9-dimethyladenine instead of 1 , compounds 2 and 4 were also obtained with N⁶,9-dimethyladenine. A possible mechanism for formation of 2 and 4 is discussed.     

1-(4-取代苯基)-4-苯基-5-(2-羟基苄基)氨基-1,2,3-三唑类衍生物的合成及抑菌活性

将邻羟苯基引入1,2,3-三唑结构中, 设计合成了10个1-(4-取代苯基)-4-苯基-5-取代-1,2,3-三唑类衍生物. 首先, 以对位取代的芳胺为原料, 经重氮化、叠氮化、闭环和缩合反应制得1-(4-取代苯基)-4-苯基-5-水杨醛亚胺-1,2,3-三唑类衍生物(3a~3e), 再用硼氢化钠还原制得1-(4-取代苯基)-4-苯基-5-(2-羟基苄基)氨基-1,2,3-三唑类衍生物(4a~4e). 目标化合物的结构经核磁、IR及元素分析确认. 抑菌活性测试表明, 当质量浓度为0.1 mg/L时, 除化合物3e和4e外, 所有化合物对白色念球菌的抑菌率均达95%以上, 对大肠杆菌的抑菌率达85%以上, 具有强抑菌活性, 表明该类化合物在抗菌药物开发方面有重要应用价值.     

The site of protonation of bifunctional bases with competing basic centers. I. Aromatic nitriles

The experimental values of the gas-phase proton affinities for a variety of 4-substituted benzonitriles, 4-substitutedN, N-dimethylanilines, and 4-substituted benzaldehydes have been examined by means of correlation analysis techniques and by ab initio quantum mechanical methods (MP2/ 6-31G(d) level). From this study it is concluded that in the gas phase, 4-(dimethylamino)-benzonitrile essentially protonates on the dimethylamino group, while protonated 4-cyanobenzaldehyde is very nearly a 21 mixture of the carbonyl- and cyano-protonated forms.This work is dedicatedin memoriam to Professor Robert W. Taft.     

Reaction of 2-dimethylaminomethylene-1,3-diones with dinucleophiles. X. synthesis of 5-substituted ethyl or methyl 4-isoxazolecarboxylates and methyl 4-(2,2-dimethyl-1-oxopropyl)-5-isoxazolecarboxylate

Reaction of ethyl or methyl 2-dimethylaminomethylene-3-oxoalkanoates with hydroxylamine hydrochloride in methanol solution afforded in high yields the relative esters of 5-substituted 4-isoxazolecarboxylic acids II . These esters were hydrolyzed generally with concentrated hydrochloric acid-acetic acid mixtures to the corresponding carboxylic acids in satisfactory yields. Ethyl or methyl esters II isomerized with sodium ethoxide or methoxide, respectively, to the corresponding esters or hemiesters of 2-cyano-3-oxoalkanoic acids generally in excellent to satisfactory yields. Reaction of methyl 5,5-dimethyl-3-dimethylaminomethylene-2,4-dioxohexanoate with hydroxylamine hydrochloride afforded in moderate yield methyl 4-(2,2-dimethyl-1-oxopropyl)-5-isoxazolecarboxylate, which was converted by acid hydrolysis as above to 4-t-butyl-4-hydroxyfuro[3,4-d]isoxazol-6-(4H)-one.     

Inhibition of human dihydrofolate reductase by 2,4-diaminoquinazolines bearing simple substituents on the aromatic ring

A series of thirty eight 2,4-diaminoquinazolines having diverse substitution patterns on the aromatic ring was evaluated for inhibitory activity against dihydrofolate reductase (DHFR) obtained from a human lymphoblast cell line. Many of these compounds were also evaluated as inhibitors of rat liver DHFR under the same experimental conditions. In most instances the results obtained with each enzyme were comparable indicating that the rodent enzyme is a suitable model for the human DHFR as far as the determination of I₅₀ values is concerned. The results demonstrate that relatively simple 5-substituted- or 5,6-disubstituted-2,4-diaminoquinazolines can be potent DHFR inhibitors. The presence of a nonpolar substituent at position 7 or 8 was highly detrimental to inhibitory potency.     

Pyrimidine derivatives. VII. Nucleophilic reactions of 5-bromo-1-(bromoalkyl)-6-bromomethyl-2,4(1H,3H)-pyrimidinediones

The reactions of 1-(bromoalkyl)-5-bromo-6-bromomethyl-3-methyl-2,4(1H,3H)-pyrimidinedione (1) with several nucleophiles were examined as follows: by reaction with sodium methoxide, 6-(bismethoxy)methyl-5-debrominated derivatives 2, 3 , and 4 were prepared; the corresponding di-substituted compounds (side chains in 1-and 6-positions) 5, 6, 7 , and 9 were obtained by treatment with silver nitrate, silver acetate, potassium thiocyanate, and potassium thioacetate; the reaction with thioacetamide and iso-butylamine gave bicyclic compounds [1,4]thiazino[4,3-c]- 11 , pyrazino[1,2-c]- 12 , and [1,4]diazepino[1,2-c]pyrimidinedione 13 , respectively; pyrrolidine, morpholine, and sodium azide afforded the corresponding 6-substituted compounds 14, 15 , and 16 .     

Synthesis of 1,2,4-triazole and thiazole analogs of ketoconazole

The synthesis of 1,2,4-triazole and thiazole analogs of ketoconazole is described in which one of the α azole ring carbons is linked to C-2 of the ketal by means of a three methylene tether. Lithiation of 1-methyl-1,2,4-triazole and thiazole and subsequent alkylation with 2-(2,4-dichlorophenyl)-2-(3-iodopropyl)-1,3-dioxolane produced, after an aqueous acidic workup, 2,4-dichlorophenyl 3-[5-(1-methyl-1,2,4-triazolyl) and 2-thiazolyl]propyl ketones, respectively. Ketalization with glycerol furnished the corresponding diastereomeric pairs of cis and trans 1,3- dioxolanes. The reaction of 2,4-dichlorophenyl 3-[5-(1-methyl-1,2,4-triazolyl)]propyl ketone with 3-mercapto-1,2-propanediol produced the corresponding diastereomeric cis and trans hydroxymethyl 1,3-oxathiolanes. The diastereomeric racemates were separated by column chromatography and their stereochemistry established by nOe nmr experiments. Some of these racemic cis ketal alcohols were converted by benzyl bromide to the corresponding benzyl ethers. Several of these racemic cis-ketals were reacted, first with methanesulfonyl chloride, then with 1-acetyl-4-(4-hydroxyphenyl)piperazine, to furnish the title compounds.     

3-(4-氯苯基)-6-取代苯氧乙酰氨基均三唑并[3,4-b]-1,3,4-噻二唑类化合物的合成

将取代苯氧乙酰氨基引入到3,6-二取代均三唑并噻二唑的分子骨架中, 设计合成了8个未见文献报道的3-(4-氯苯基)-6-取代苯氧乙酰氨基均三唑并[3,4-b]-1,3,4-噻二唑类化合物5a～5h, 结构经元素分析、IR和¹H NMR等测试得到确证.     

Synthesis of some new 4,5-substituted-4H-1,2,4-triazole-3-thiol derivatives

In this study appropriate hydrazide compounds, furan-2-carboxylic acid hydrazide (1) and phenylacetic acid hydrazide (2) were converted into 1,4-substituted thiosemicarbazides 4a-e and 5a-e and 4-amino-5-(furan-2-yl or benzyl)-4H-1,2,4-triazole-3-thiols 7 and 10. The 1,4-substituted thiosemicarbazides were then converted into 5-(furan-2-yl or benzyl)-4-(aryl)-4H-1,2,4-triazole-3-thiols 8a-e and 9a-e. In addition, the azomethines 11a-d and 12a-d were prepared from the corresponding arylaldehydes and the 4-amino-5-(furan-2-yl or benzyl)-4H-1,2,4-triazole-3-thiols 7 and 10. The structures of all the synthesized compounds were confirmed by elemental analyses, IR, (1)H-NMR and(13) C-NMR spectra.     

Synthesis of 2,4-diaminoquinazolines and tricyclic quinazolines by cascade reductive cyclization of methyl N-cyano-2-nitrobenzimidates

An efficient route to N(4)-substituted 2,4-diaminoquinazolines has been developed by employing tandem condensation of cyanoimidate-amine and reductive cyclization in iron-HCl system. This method is tolerant of a following intramolecular N-alkylation and produces two fused heterocycles in a one-pot procedure. This protocol is a facile two-step synthesis of tricyclic quinazolines, which is effected by potent cyanoimidation and tandem reductive cyclization from 2-nitrobenzaldehydes. Moreover, the forming process of tricyclic quinazolines has been investigated from the ring-opening/ring-closing cascade point of view. It is found that the preparation of tricyclic quinazolinones in good yields relies on the selective hydrolysis of tricyclic quinazolines in base or acid system.     

Reactions of o-aminonitriles with isocyanates. 1. A two-step synthesis of 2,6-dihydroimidazo[1,2-c]quinazolin-5-(3H)one

The reaction of anthranilonitrile with 2-chloroethyl isocyanate yields 2-[3-(2-chloroethyl)ureido]benzo-nitrile ( 6 ) which, upon heating, or treatment with base, undergoes a double cyclization to form 2,6-dihydroimidazo[1,2-c]quinazolin-5-(3H) one ( 8 ) in excellent yield. When heated with hydrochloric acid, 6 is converted initially into 2-(2-chloroethylamino)-4H-[3,1]benzoxazin-4-one ( 18 ) and further into 3-(2-chloroethyl)-2,4-(1H,3H)quinazolinedione ( 15 ). The acid-catalyzed reaction of 2,3-dihydro-5H-oxazolo[2,3-b]quinazolin-5-one ( 14 ) with nucleophilic reagents yields 3-substituted 2,4-(1H,3H)quinazolinediones.     

2-[3-(Trifluoromethyl)phenyl]furo[3,2-b]pyrroles: synthesis and reactions

The synthesis and reactions of methyl 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole-5-carboxylate (1a) are described. Upon reaction with methyl iodide, benzyl chloride, or acetic anhydride, this compound gave N-substituted products 1b-d. By hydrolysis of compounds 1a-c, the corresponding acids 2a-c were formed, or by reaction with hydrazine-hydrate, the corresponding carbohydrazides 3a-c were formed. By heating 2-[3-(trifluoromethyl)phenly]-4H-furo[3,2-b]pyrrole-5-carboxylic acid (2a) in acetic anhydride, 4-acetyl-2-[3-(trifluoromethyl)phenyl]furo[3,2-b]pyrrole (4) was formed. By hydrolysis of 4, 2-[3-(trifluoromethyl)phenyl]-4H-furo[3,2-b]pyrrole (5a) was formed, and reactions with methyl iodide or benzyl chloride gave N-substituted products 5b-c. The reaction of 4 with dimethyl butynedioate gave substituted benzo[b]furan 6. Compound 3a reacted with triethyl orthoesters giving 7a-c, which afforded with phosphorus (V) sulphide the corresponding thiones 8a-c. The thiones 8a-c reacted with hydrazine hydrate to form hydrazine derivatives 9a-c. The reaction of triethyl orthoformiate with compounds 9a-c led to furo[2′,3′: 4,5]pyrrolo[1,2-d][1,2,4]triazolo[3,4-f][1,2,4]triazines 10a-c. Hydrazones 11a-c were formed from 3a-c and 5-[3-(trifluoromethyl)phenyl]furan-2-carboxaldehyde. The effect of microwave irradiation on some condensation reactions was compared with “classical” conditions. The results showed that microwave irradiation shortens the reaction time while affording comparable yields.