Synthesis and antibacterial activity of thioglycolic amino acid derivatives and dipeptides containing the 2-methyl-3,4-dihydroquinazolin-4-one moiety

3-(2′-Chloroethyl)-2-methyl-3,4-dihydroquinazolin-4-one ( I ) was reacted with sodio (sodium thioglycolate) in dry dioxane and yielded compound II . By using thionyl chloride, this compound was converted to the corresponding acid chloride ( III ). The prepared acyl chloride ( III ) was allowed to interact with different α-amino acids such as Gly, L -Ala, L -B-Phe, DL -Asp, L -Glu, L -Thr and L -Val to give new amino acid derivatives ( IVa – g ). A selected C-terminal derivative of glycine ( IVa ) was converted into acid chloride ( V ). The acid chloride formed was reacted with L -Ala, L -B-Phe, DL -Asp, L -Glu, L -Thr and L -Val and yielded the new dipeptides VIa – f . The structures of the synthesized compounds were elucidated by elemental analysis and IR spectra. The prepared peptides were tested for their antimicrobial activities by comparison with tetra-cycline as a reference compound.     

Synthesis of some new heterocyclic systems derived from 2-acetylbenzimidazole

The named compound was reacted with thiosemicarbazide and/or semicarbazide to produce the corresponding condensation products II and V respectively. Reaction of II with chloroacetic acid in ethanol containing anhydrous sodium acetate yielded III. Condensation of III with aromatic aldehydes yielded the corresponding arylidene derivatives (IV). Oxidation of the semicarbazone V with selenium dioxide gave 2-(1,2,3-selenadiazole-4-yl)benzimidazole (VIa, b) while with thionyl chloride it gave 2-(1,2,3-thiadiazole-4-yl)benzimidazole (VIIa, b). The chalcones of 2-acetyl and/or 1-methyl-2-acetylbenzimidazole were condensed with hydrazine hydrate, phenylhydrazine and/or hydroxylamine to produce 2-(5-aryl-1(H)-pyrazolin-3-yl)-, 2-(5-aryl-1-phenyl-2-pyrazolin-3-yl)- and 2-(5-aryl-2-isoxazolin-3-yl)benzimidazole (IX, X, XI) respectively.     

Synthesis of some new thiophene derivatives with antimicrobial activity. part I

For possible antimicrobial activity, thiophene-2-sulphonyl chloride was condensed with primary or secondary amines, phenols and hydrazine hydrate. Thiopene-2-sulphonhydrazones and thiophene-2-sulphoniminoazo derivatives were obtained. The constitution of some of the prepared products is discussed in the light of their infrared spectra. The biological activities of all prepared compounds were tested.     

Synthesis and antimicrobial activity of some new 2-(3-chloro-1-benzothiophen-2-yl)-3-(substituted-phenyl)-4- (3H)-quinazolinones derivatives

3-Chloro-1-benzothiophene-2-carbonylchloride 1 reacted with anthranilic acid in pyridine to give compound 2. The main aim of the work is to study the behavior of this 4H-3,1-benzoxazin-4-one toward nitrogen nucleophiles. The compound reacted with aromatic amines, hydroxylamine hydrochloride, formamide, thioglycolic acid, thiosemicarbazide and acid chlorides to give various 3-substituted quinazolinones, respectively. The structures of all the synthesized compounds were confirmed by spectral data and have been screened for antibacterial and antifungal activity.

     

Synthesis of novel pyridazine derivatives as potential antimicrobial agents

A series of novel pyridazine derivatives incorporated with triazole, thiazolidine, imidazolidine, oxazine, and quinazoline moieties was synthesized by the reaction of [6-(4-phenoxyphenyl)pyridazin-3-yloxy]acetyl isothiocyanate with variety of nucleophilic reagents. The structures of all products were confirmed and characterized by the elemental analysis and spectroscopic studies (IR, MS, ¹H NMR). Also, the products were investigated for their antibacterial and antifungal activities and were compared with the standard drugs. Most of the synthesized compounds demonstrated potent to weak antimicrobial activity.     

串连aza-Wittig反应合成2-芳氧(硫)基-3-苯基喹唑啉-4-酮

用膦亚胺、异氰酸苯酯与取代酚发生三组分串连aza-Wittig反应制得7个喹唑啉酮类衍生物,用元素分析、IR、^1HNMR表征了它们的结构。     

5-甲氧羰基-4-(4-甲氧苯基)-6-甲基-3,4-二氢嘧啶-2-酮的合成

在固体酸的催化下，茴香醛、乙酰乙酸甲酯与脲进行环化缩合，一步合成了5－甲氧羰基－4－（4－甲氧苯基）－6－甲基－3，4－二氢嘧啶－2－（1H）酮，通过改变各种实验因素，找到了合成标题化合的最佳实验条件。即茴香醛0.05mol，乙酰乙酸甲酯0.06mol.脲0.75 mol，NH2SO3H1.5g，无水乙醇为溶剂，反应时间为0．6h，选用此实验条件收率可达95％以上。     

2-(3,4-二氯苯基)-2,4-二氢-5-甲基-3H-吡唑啉-3-酮的合成及表征

本文以3,4-二氯苯胺为原科合成了3,4-二氯苯肼盐酸盐,再与乙酰乙酸乙酯环化,合成2-(3,4-二氯苯基)-2,4-二氢-5-甲基-3H-吡唑啉-3-酮.用红外光谱、熔点仪、高效液相色谱和核磁共振对产品进行了表征和检测.考察了盐酸用量、还原剂、反应温度、溶剂和后处理对转化率和纯度的影响.结果表明:选用氯化亚锡作还原剂,在低温和盐酸过量下有利于提高3,4-二氯苯肼盐酸盐的收率.选用V(乙醇)∶V(水)=6∶1为溶剂,75℃下反应4小时,以碳酸钠调节pH =7,2-(3,4-二氯苯基)-2,4-二氢-5-甲基-3H-吡唑啉-3-酮转化率为82.6％,熔点163～164℃,纯度述96％.     

Synthesis and application of some new oxazole derivatives as antimicrobial agents

5-(p-Acetylphenyl)-2-phenyloxazole ( I ) was condensed with aromatic aldehydes to furnish chalcones 2a-e . Cyclocondensation of 2a-e with hydrazine hydrate and with phenyl hydrazine led to the formation of pyrazoline derivatives 3a-e and 4a-e respectively. Similarly, 2a was interacted with hydroxylamine to give isoxazoline ( 5 ). On the other hand, condensation of 1 with phenyl hydrazine yielded hydrazone 6 which on treatment with Vilsmeier reagent (DMF/POCl₃) gives 5-[p-(4-formyl-1-phenylpyrazol-3-yl)phenyl]-2-phenyloxazole ( 7 ). Also, a few derivatives of 7 have been prepared. Moreover, all compounds were screened for their antimicrobial activity against some strains of bacteria and fungi.     

Electrogenerated base-promoted synthesis and antimicrobial activity of 2-imino-1,3-thiazolidin-4-one derivatives

Electrogenerated cyanomethylanions obtained by reduction of dry acetonitrile at a steel grid cathode were used to promote the addition of ethyl bromoacetate to thiourea derivatives. The reaction yields the corresponding 2-imino-1,3-thiazolidin-4-one. The reaction pathway was discussed based on the kinetic and thermodynamic data obtained by computational methods. In addition, the biological activity of these new compounds was also investigated.     

微波辐射下合成4-(4-氯苯基)-6-甲基-5-乙氧羰基-3,4-二氢嘧啶-2(1H)-酮

研究了微波辐射催化合成标题化合物的方法。最优合成条件:催化剂氨基磺酸0.8g,微波功率240W,辐射时间4min,n4-氯苯甲醛∶n乙酰乙酸乙酯∶n尿素为1.0∶1.2∶1.5,在此条件下产率达94.2%。     

Synthesis of some novel 2-oxo-pyrano(2,3-b)- and 2-oxo-pyrido(2,3-b)quinoline derivatives as potential antimalarial,diuretic, clastogenic and antimicrobial agents

The 2-chloro-3-formyl quinoline derivatives ( 1a–e ) on treatment with acetic anhydride and sodium acetate, afforded the corresponding novel 2-oxo-pyrano(2,3-b) quinoline derivatives ( 2a–e ), and these were subjected to ammonia treatment to yield the corresponding naphthyridine derivatives ( 3a–e ). The prepared compounds ( 2a–e ) were tested for their antimalarial, diuretic, clastogenic and antimicrobial properties. Not all the compounds showed a diuretic effect and the significant increase in the frequency of micronuclei shows that they are non-clastogens, whereas the 7-chloro derivative ( 2e ) was a very effective antimalarial agent against the mosquito species. All the compounds were found to have optimum antimicrobial activity against Staphylococcus aureus, Escherichia coli and Salmonella typhi. Compounds 2d and 2e were found to be most active against the bacteria tested. © 1998 SCI     

Synthesis of (2′-Methyloxiranyl)quinones as bioreductive alkylating agents

1,4-Benzoquinones and 1,4-naphthoquinones bearing 2′-methyloxiranyl substituents have been synthesized as new bioreductive alkylating agents. The method presented here involved the synthesis of 2-acetyl-1,4-dimethoxybenzenes 6a, b, d and -naphthalenes 6c, e, f , conversion of the acetyl group into 2′-methyloxirane ring using trimethylsulfonium chloride and sodium hydroxide in anhydrous medium, and oxidative demethylation of these intermediates 7a-f to quinones 8a, c, e, f with silver(II) dipicolinate.     

Discovery of N-arylalkyl-3-hydroxy-4-oxo-3,4-dihydroquinazolin-2-carboxamide derivatives as HCV NS5B polymerase inhibitors

The metal ion chelating β-N-hydroxy-γ-ketocarboxamide pharmacophore was integrated into a quinazolinone scaffold, leading to N-arylalkyl-3-hydroxy-4-oxo-3,4-dihydroquinazolin-2-carboxamide derivatives as hepatitis C virus (HCV) NS5B polymerase inhibitors. Lead optimization led to the identification of N-phenylpropyl carboxamide 9 k (IC(50) =8.8 μM). Compound 9 k possesses selectivity toward HCV1b replicon Ava.5 cells (EC(50) =17.5 μM) over parent Huh-7 cells (CC(50) =187.5 μM). Compound 9 k effects a mixed mode of NS5B inhibition, with NTP-competitive displacement properties. The interaction between 9 k and NS5B is stabilized by the presence of magnesium ions. Docking studies showed that the binding orientation of 9 k occupies the central portions of both magnesium-mediated and NTP-ribose-response binding sites within the active site region of NS5B. As a result, 3-hydroxy-4-oxo-3,4-dihydroquinazolin-2-carboxamide derivatives are disclosed herein as novel, mainly active site inhibitors of HCV NS5B polymerase.     

Synthesis and Evaluation of 1,1′‐Hydrocarbylenebis(indazol‐3‐ols) as Potential Antimalarial Drugs

Bis(indazol‐3‐ol) derivatives ( 5 , 30–38 ) were prepared by alkylation of 3‐alkoxyindazoles with α,ω‐dibromides, followed by removal of the O‐protecting groups. These compounds were subsequently evaluated as inhibitors of biocrystallization of ferriprotoporphyrin IX (heme) to hemozoin, a Plasmodium detoxification specific process. Most bis(5‐nitroindazol‐3‐ols) were good inhibitors, however, a denitro analogue ( 38 ), the intermediate bis(3‐alkoxyindazoles) ( 15 – 29 ) as well as bis(indazolin‐3‐ones) ( 39 – 42 ) were not active, showing the importance of the NO₂ and OH groups in the inhibition process.     

3-(5-芳基-[1,3,4]噁二唑-2-亚甲硫基)-5-(4-硝基吡咯)-2-基-4-芳基-[1,2,4]三唑的合成及抗菌活性

用3-(4-硝基吡咯)-2-基-4-芳基-1,2,4-三唑-5-硫醇与5-芳基-2-氯甲基-1,3,4-二唑缩合,得到10个新型多杂环化合物。其结构经元素分析、IR、MS及~1HNMR确证。研究了目标化合物的体外抗菌活性(MIC和IC_(50))。结果显示,化合物3-(5-对氯苯基-[1,3,4]二唑-2-亚甲硫基)-5-(4-硝基吡咯)-2-基-4-苯基-[1,2,4]三唑和3-(5-对氯苯基-[1,3,4]二唑-2-亚甲硫基)-5-(4-硝基吡咯)-2-基-4-对甲基苯基-[1,2,4]三唑表现出一定的体外抗菌活性,含硝基吡咯环的二唑多杂环类化合物有可能成为新型结构的抗菌药物。