Reaction of 4-Aryl-1-(4-oxo-3,4-dihydrothieno-[2,3-d]pyrimidin-2-yl)thiosemicarbazides with Dimethyl Acetylenedicarboxylate

4-Aryl-1-(4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-2-yl)thiosemicarbazides react with dimethyl acetylenedicarboxylate in methanol to give the corresponding methyl {3-aryl-4-oxo-2-[(4-oxo-3,4-dihydro-thieno[2,3-d]pyrimidin-2-yl)hydrazono]-1,3-thiazolidin-5-ylidene}acetates, whereas in dioxane methyl 5-aryl-amino-2-methoxycarbonylmethyl-3-(4-oxo-3,4-dihydrothieno[2,3-d]pyrimidin-2-yl)-2,3-dihydro-1,3,4-thiadiazole-2-carboxylates are mainly formed.     

Synthesis of 1,2,4-triazole, 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazine derivatives of benzotriazole

A novel series of 1-(1-carbonylmethyl-1H-benzotriazole) thiosemicarbazides 3a-e was synthesized and then cyclized with sodium hydroxide to afford 1-(4-substituted-4H-1,2,4-triazole-3-thion-5-yl)methyl-1H-benzotriazoles 4a-e , which were alkylated with ethyl iodide to l-(3-ethylthio-4-substituted-4H-1,2,4-triazol-5-yl)-methyl-1H-benzotriazoles 5b-e . The reaction of 1H-benzotriazol-1-acetic acid hydrazide ( 2 ) with carbon disulphide and potassium hydroxide followed by hydrazine hydrate gave 1-(4-amino-4H-1,2,4-triazole-3-thion-5-yl)methyl-1H-benzotriazole ( 6 ). Its subsequent condensation with carboxylic acids in the presence of phosphorus oxychloride or with phenacyl bromides afforded two series of fused heterocycles namely; 6-substituted-3-[1-(1H-benzotriazole)methyl]-1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles 7a-e and 6-substituted phenyl-3-[1-(1H-benzotriazole)methyl]-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazines 8a-e respectively. The structure of the newly synthesized compounds was elucidated by elemental analyses, ir and nmr spectra.     

Syntheses of substituted-oxazolo-1,3,4-thiadiazoles, 1,3,4-oxadiazoles,and 1,2,4-triazoles

Starting from readily available methyl 5-methyloxazole-4-carboxylate ( 1 ) and 4-methyl-5-oxazolylcar-boxylic acid hydrazide ( 11 ) the title compounds were prepared. The reaction of compound 1 with hydrazine hydrate afforded the corresponding hydrazide 2 . The reaction of compound 2 with formic acid yielded 1-formyl-2-(5-methyloxazole-4-carboxyl)hydrazine ( 3 ). Refluxing of the latter with phosphorus pentasulfide in xylene gave compound 5 in 62% yield. The reaction of compound 3 with phosphorus pentoxide afforded compound 4 . Starting from hydrazide 11 , compounds 13 and 14 were prepared similarly. Reaction of compound 2 with substituted isothiocyanate yielded compound 9 which was cyclized in basic medium to 4-alkyl-5-(5-methyl-4-oxazolyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione ( 10 ). The isomer 19 was prepared similarly. Methylation and subsequent oxidation of compound 19 gave compound 21 . Reaction of the acid 7 with thiosemicarbazide in the presence of phosphorus oxychloride gave 2-amino-5-(5-methyl-4-oxazolyl)1,3,4-thiadiazole ( 8 ). 2-Amino-5-(4-methyl-5-oxazolyl)-1,3,4-thiadiazole ( 17 ) was prepared from acyl chloride 15 by the usual method.     

含噁二唑肟醚取代的均三唑水杨醛席夫碱的合成及抗菌活性

4-氨基-5-(4-甲氧苯基)-3-巯基-均三唑(2)在无水乙酸钠作用下与β-氯苯丙酮(3)缩合得氨基三唑硫代苯丙酮(4). 化合物4与盐酸羟胺肟化得羰基肟化物5, 接着与水杨醛缩合得到席夫碱肟6, 用氯甲基噁二唑7a～7e对化合物6的肟羟基醚化得到目标物均三唑噁二唑肟醚1a～1e. 所合成的新化合物结构由元素分析和光谱数据表征, 体外抗菌活性也被试验.     

1,2,3-Selenadiazolyl-1,3,4-oxadiazole, 1,2,3-Thiadiazolyl-1,3,4-oxadiazole and 5-(1,2,3-Thiadiazolyl)-s-triazolo[3,4-b]-1,3,4-thiadiazoles

A series of 5-substituted-2-(4-alkyl or phenyl-1,2,3-thia(or selena)diazol-5-yl)-1,3,4-oxadiazoles were prepared. 5-Substituted-2-(4-phenyl-1,2,3-selenadiazol-5-yl)-1,3,4-oxadiazoles upon pyrolysis afforded the corresponding alkynes. Also, a series of 5-substituted-4-amino-3-(1,2,3-thiadiazol-5-yl)-s-triazoles and 5-(1,2,3-thiadiazolyl)-s-triazolo[3,4-b]-1,3,4-thiadiazoles were prepared.     

Design and synthesis of novel quinoline derivatives bearing oxadiazole,isoxazoline, triazolothiadiazole,triazolothiadiazine, and piperazine moieties

A new series of 2,3-disubstituted quinoline derivatives were synthesized from 2-chloroquinoline-3-carbaldehyde. In the reaction sequence, acetanilide was cyclized to give 2-chloroquinoline-3-carbaldehyde 1 , which was transformed to 2-(4-phenylpiperazin-1-yl)quinolin-3-carbaldehyde 2 by reaction with 4-phenylpiperazine in DMF-containing anhydrous K₂CO₃; then, compound 2 was oxidized by iodine in methanol, and methyl 2-(4-phenylpiperazin-1-yl)quinoline-3-carboxylate 3 was synthesized. The key intermediate 4 , 4-amino-5-[2-(4-phenylpiperazin-1-yl)quinolin-3-yl]-4H-1,2,4-triazole-3-thiol, was prepared using the ester 3 by a series of step. Reaction of 5 with various aromatic carboxylic acids or phenacyl bromides yielded 1,2,4-triazolo[3,4-b][1,3,4]thiadiazoles 5a-c and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazines 6a-c , respectively. Moreover, compound 2 condensed with o-phenylenediamine to give 2-[2-(4-phenylpiperazin-1-yl)quinolin-3-yl]-1H-benzimidazole 7 . Interaction of 7 and 2-chloromethyl-5-aryl-1,3,4-oxadiazoles in the presence of K₂CO₃ led to the title compounds 8a-c . Furthermore, 4,5-dihydroisoxazoline derivatives 9a-c were obtained by the reaction of readily accessible starting materials including 2-(4-phenylpiperazin-1-yl)quinolin-3-carbaldehyde 2 , 1-phenyl-2-(triphenylphosphoranylidene)ethanone and hydroximoyl chlorides under mild conditions in the presence of Et₃N. The hydrazone intermediates 10a-c were obtained by the condensation of 2 with aroylhydrazides in ethanol, then, refluxing in acetic anhydride yielded 3-acetyl-5-aryl-2-[2-(4-phenylpiperazin-1-yl)quinolin-3-yl]-2,3-dihydro-1,3,4-oxadiazoles 11a-c . Structures of these compounds were established by their elemental analysis, IR, ¹H NMR, and mass spectral data.     

Synthesis and biological evaluation of some new substituted benzoxazepine and benzothiazepine as antipsychotic as well as anticonvulsant agents

Various 2-((2-((5-benzylideneamino)-1,3,4-oxa/thiadiazol-2-yl)methyl)hydrazinyl) methyl)benzo[b][1,4]oxa/thiazepin-4(5H)-ones (4a–4l), 2-((2-((5-(4-oxo-2-substitutedphenyl thiazolidin-3-yl)-1,3,4-oxa/thiadiazol-2-yl)methyl)hydrazinyl)methyl)benzo [b] [1,4]oxa/thiazepin-4(5H)-ones (5a–5l) and 2-((2-((5-(3-chloro-2-(substitutedphenyl)-4-oxoazetidin-1-yl)-1,3,4-oxa/thia diazol-2-yl)methyl)hydrazinyl)methyl)benzo[b][1,4]oxa/thiazepin-4(5H)-ones (6a–6l) have been synthesized. The structures of these compounds have been established by elemental (C, H, N) and spectral (IR, ¹H-NMR and Mass) analysis. The synthesized compounds were screened for their antipsychotic and anticonvulsant activities. Compound 5l was found to be the most active compound of this series.     

Synthesis and antitumor activity of novel pyridazinone derivatives containing 1,3,4-thiadiazole moiety

Abstract

A series of novel pyridazinone derivatives containing the 1,3,4-thiadiazole moiety were synthesized and characterized by ¹H NMR, 13C NMR, spectroscopies HRMS and IR. Among them, the structure of compound 5c (2-(Tert-butyl)?4-chloro-5-((5-((2-ethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was unambiguously confirmed via single crystal X-ray diffraction analysis. The inhibitory activity of all the target compounds against MGC-803 and Bcap-37 was determined by MTT assay, with doxorubicin (the inhibition rates were 95.5?±?0.4% and 95.7?±?1.0% respectively) as a control. The preliminary results showed that the inhibitory activity of compound 5n (2-(Tert-butyl)?4-chloro-5-((5-((3-fluorophenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was superior to the others. The inhibition rates of MGC-803 and Bcap-37 cells were 86.3?±?2.2% and 92.3?±?0.6% at a concentration of 10?μmol/L, respectively. The preliminary structure-activity relationship showed that when the 2-position of the benzene ring was substituted by a methyl group, such as compound 5j (2-(Tert-butyl)?4-chloro-5-((5-((2,3-dimethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), it exhibited good anticancer activity on MGC-803 cells. Besides, introducing fluorine, chlorine, or trifluoromethyl group onto the benzene ring, such as compound 5?m (2-(Tert-butyl)?4-chloro-5-((5-((4-(trifluoromethoxy)phenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), displayed good anticancer activity on MGC-803 and Bcap-37 cells.     

A selective synthesis of 2-arylamino-4H-1,3,4-thiadiazino[5,6-b]-quinoxalines and mesoionic triazolo[4,3-a]quinoxaline

The reaction of the 6-chloro-2-(1-methyl-2-thiocarbamoylhydrazino)quinoxaline 4-oxides 3a-d with trifluoroacetic anhydride gave the 2-(N-aryl)trifluoroacetamido-8-chloro-4-methyl-4H-1,3,4-thiadiazino-[5,6-b]quinoxalines 7a-d , respectively, while the reflux of compounds 3a-c in N,N-dimethylformamide afforded the mesoionic triazolo[4,3-a]quinoxaline 4 . Hydrolysis of compounds 7a-d with triethylamine/water provided the 2-arylamino-8-chloro-4-methyl-4H-1,3,4-thiadiazino[5,6-b)]quinoxalines 8a-d , respectively.     

1,3,4-THIADIAZOLES. REGIOSELECTIVE O-DEMETHYLATION ON DEHYDRATIVE CYCLIZATION OF 1-(3,4,5-TRIMETHOXYBENZOYL)4-SUBSTITUTED THIOSEMICARBAZIDES WITH SULPHURIC ACID

Cyclization of 1-(3,4,5-trimethoxybenzoyl)-4-substituted thiosemicarbazides 2a–g with sulphuric acid at ambient temperature afforded the selectively demethylated products 2-(4-hydroxy-3,5-dimethoxyphenyl)-5-substituted amino-1,3,4-thiadiazoles 4a–g. Meanwhile, dehydrative cyclization of 1-(3,4,5-trimethoxybenzoyl)-4-(benzyl or t-butyl)thiosemi- carbazides 2h, i with sulphuric acid yielded 2-(4-hydroxy-3,5-dimetho xyphenyl)-5-amino-1,3,4-thiadiazole 5. On the other hand, dehydration of 2h, i by heating with phosphorus oxychloride yielded 2-(3,4,5-trimethoxyphenyl)-5-amino-1,3,4-thiadiazole 6.     

Synthesis of 5-amino-1,3,4-thiadiazoles containing dithiocarbamate groups

Synthesis of alkyl ((5-[alkylamino]-1,3,4-thiadiazol-2-yl)methyl)carbamodithioates via the reaction of glycine-based dithiocarbamates with thiosemicarbazides in the presence of POCl₃ in ethanol is disclosed. The main advantages of this method including the use of ethanol as solvent, no need to column chromatography for purification and high to excellent yields of products are noteworthy.     

Synthesis and biological activities of benzothiazole derivatives bearing a 1,3,4-thiadiazole moiety

A series of benzothiazole derivatives bearing a 1,3,4-thiadiazole moiety were designed, synthesized and evaluated for their antibacterial, antifungal and antiviral activities. The bioassay results indicated that most of target compounds showed good antiviral activities against tobacco mosaic virus (TMV) and antibacterial activities against Xanthomonas oryzae pv. oryzae (Xoo) and Ralstonia solanacearum (Rs). Especially, the anti-Xoo effect of title compounds 5k (N-(5-methoxybenzo[d]thiazol-2-yl)-2-((5-(2-tolyl)-1,3,4-thiadiazol-2-yl)thio)acetamide) and the anti-Rs effect of title compounds 5a (N-(5-nitrobenzo[d]thiazol-2-yl)-2-((5-(4-(trifluorom ethyl)phenyl)-1,3,4-thiadiazol-2-yl)thio)acetmide) respectively reached 52.4% and 71.6% at 100?µg/mL, which are superior to that of bismerthiazol (32.0% and 52.3%). In addition, the protective and inactivation activities of title compound 5i (N-(5-methoxybenzo [d]thiazol-2-yl)-2-((5-(4-nitrophenyl)-1,3,4-thiadiazol-2-yl)thio)acetamide) against TMV were 79.5% and 88.3%, respectively, which are better than that of ningnanmycin (76.4% and 86.8%). The above research showed that benzothiazole derivatives bearing a 1,3,4-thiadiazole moiety may be used as potential molecular templates in searching for highly-efficient antiviral and antibacterial agents.     

Synthesis and anti-arrhythmic activity of some piperidine-based 1,3-thiazole, 1,3,4-thiadiazole, and 1,3-thiazolo[2,3-c]-1,2,4-triazole derivatives

Abstract  The reaction of 1-[4-(piperidin-1-yl)benzylidene]thiosemicarbazide with hydrazonoyl chlorides afforded 1,3-thiazole derivatives. Cyclization of two compounds of the latter 1,3-thiazole by means of bromine in the presence of sodium acetate at room temperature gave 1,3-thiazolo[2,3-c]-1,2,4-triazole derivatives. The reaction of 2-cyano-3-(4-piperidin-1-ylphenyl)prop-2-enethioamide with hydrazonoyl chlorides under reflux in ethanol in the presence of triethylamine yielded 1,3-thiazoles. Treatment of 3-oxo-3-(piperidin-1-yl)propanenitrile with phenyl isothiocyanate in DMF, in the presence of KOH, at ambient temperature, resulted in the formation of 3-anilino-3-mercapto-2-(piperidin-1-ylcarbonyl)acrylonitrile which was reacted with hydrazonoyl chlorides to yield the corresponding 1,3,4-thiadiazole derivatives. Some of the newly synthesized compounds had significant anti-arrhythmic activity. Graphical Abstract        

Synthesis and in-vitro antioxidant activities of some coumarin derivatives containing 1,2,3-triazole ring

A new green protocol was developed for the S-alkylation of 2-mercapto-1,3,4-oxadiazole by the reaction of 5-substituted-2-mercapto-1,3,4-oxadiazole with propargyl bromide in sodium bicarbonate in water. The newly synthesized 5-[(substitutedphenoxy)methyl]-2-[(prop-2-yn-1-yl)sulfanyl]-1,3,4-oxadiazole when reacted with azidomethyl coumarins underwent regioselective reaction yielding 4-(((4-((5-((substitutedphenoxy)methyl)-1,3,4-oxadiazol-2-yl)sulfanylmethyl)-1H-1,2,3-triazol-1-yl)methyl)-6-methyl)-2H-chromene-2-one or 1-((4-((5-((substitutedphenoxy)methyl)-1,3,4-oxadiazol-2-yl)sulfanylmethy)-1H-1,2,3-triazol-1-yl-)methyl)-3H-benzo[f]chromene-3-one. Structures of the newly synthesized compounds were confirmed by spectral and analytical data. The compounds were screened for their in-vitro antioxidant property.     

A simple and efficient approach for the synthesis of a novel class aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives via intramolecular nucleophilic substitution reaction

In this study, we synthesized a new series of substituted aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives (6-24) in yields ranging from 42 to 70% with an interesting mechanism that involves internal nucleophilic substitution followed by an S_N2-type nucleophilic substitution. First, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanone (3) was synthesized from the reaction of 5-methyl-1,3,4-thiadiazole-2-thiol (1) with 2-bromo-1-(4-chlorophenyl)ethanone (2) in the presence of potassium hydroxide. Then, 1-(4-chlorophenyl)-2-((5-methyl-1,3,4-thiadiazol-2-yl)thio)ethanol (4) was synthesized by a reduction reaction of this compound using NaBH₄. Finally, 5-methyl-3-alkyl-1,3,4-thiadiazol-2(3H)-one derivatives (6-24), which are the target compounds, were synthesized from the reaction of this compound (4), which is a secondary alcohol with various alkyl halides (5a-n) in the presence of sodium hydride (NaH). This study presents an interesting reaction mechanism related to the synthesis of aliphatic 1,3,4-thiadiazol-2(3H)-one derivatives that is not recorded in the literature.     

A Facile Synthesis of Aryl‐Substituted Hydrazono‐Pyrazolyl[1,2,4]triazolo[3,4‐b][1,3,4][thiadiazol]‐coumarin Derivatives

Some inimitable and therapeutic coumarin‐substituted fused[1,2,4]triazolo‐[3,4‐b][1,3,4]thiadizole derivatives were synthesized by the cyclocondensation reaction of 2‐oxo‐2H‐chromene‐3‐carboxylic acid ( 1 ) and 4‐amino‐5‐hydrazinyl‐4H‐[1,2,4]‐triazole‐3‐thiol ( 2 ) by using phosphorous oxychloride as a cyclizing agent. This cyclized intermediate 3‐(3‐hydrazino‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazol‐6‐yl)‐chromen‐2‐one ( 3 ) later condensation with various ethyl 2‐(2‐arylhydrazono)‐3‐oxobutanoates ( 4 ) in NaOAc/MeOH under reflux conditions afforded the corresponding new series of aryl‐substituted hydrazono‐pyrazolyl‐[1,2,4]triazolo[3,4‐b][1,3,4][thiadiazol]‐coumarin derivatives ( 5 ) in good to excellent yields. The structures of newly synthesized compounds were established on the basis of elemental analysis, IR, ¹H NMR and mass spectroscopic studies.     

Reactions with Hydrazonoyl Halides 611: Synthesis of 2,3-Dihydro-1,3,4-Thiadiazoles

2-[1,2-Diaza-3-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))prop-2-enylidene]-3-phenyl-5-substituted 1,3,4-thiadiazolines and 2-{[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]cyanomethylene}-3-phenyl-5-substitu- ted 1,3,4-thiadiazolines were synthesized from hydrazonoyl halides and 4-{-2-aza-2-[(methylthiothioxomethyl)amino]vinyl}-2,3-dimethyl-1-phenyl-3-pyrazoin-5-one and 2-[4-(2,3-dimethyl-5-oxo-1-phenyl-3-pyrazolin-4-yl)-1,3-thiazol-2-yl]ethane-nitrile, respectively. All synthesize compounds were elucidated by elemental analysis, spectra, and alternative synthesis routes, whenever possible.     

Design and synthesis of some new thiophene and 1,3,4-thiadiazole based heterocycles

Abstract

The reaction of 3-oxopropanenitriles with phenyl isothiocyanate in DMF containing KOH afforded the corresponding potassium salts. The latter salts were converted into ketene N,S-acetals upon acidification with hydrogen chloride. The reaction of the ketene N,S-acetals with 2-bromo-1-[5-methyl-1-(p-tolyl)-1H-1,2,3-triazol-4-yl]ethan-1-one or 3-(2-bromoacetyl)-2H-chromen-2-one gave novel thiophenes in good yields. Treatment of the ketene N,S-acetals with hydrazonyl halides afforded 1,3,4-thiadiazoles in good yields. The stereochemistry of the synthesized compounds was studied.     

Synthesis of Some 3-Substituted 1,2-Dihydroindoles

The reaction of 4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6-methyl carboxylate 2 with hydrazine hydrate in methanol gave 4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6-carbonylhydrazine 3. Furthermore, the reaction of 3 with carbon disulfide and then hydrazine hydrate afforded 3-[6-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-4-oxo-1,3-thiazin-2-yl] hydrazone-1,3-dihydroindol-2-one 5. the latest reacted with DMAD to give {6-hydroxy-3-[4-oxo-2-(2-oxo-1,2-dihydroindol-3-ylidene)hydrazone-1,3-thiazin-6yl]-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-7-ylidene}methoxycarbonylmethylene 6.     

A new method for the synthesis of 6H,11H-indolo[3,2-c]-isoquinolin-5-ones/thiones and their reactions

The synthesis of 8-substituted and unsubstituted 6H,11H-indolo[3,2-c]isoquinolin-5-ones/thiones 3a-c and 4a-c and their derivatives viz, ethyl (8-substituted-6H,11H-indolo[3,2-c]isoquinolin-5-on-6-yl)acetates 5a-c , (8-substituted-6H,11H-indolo[3,2-c]isoquinolin-5-on-6-yl)acetyl hydrazides 6a-c , 3,5-disubstituted-pyrazoles 7a-c and 8a-c , 3-substituted-pyrazol-5-ones 9a-c and 5-(8-substituted-6H,11H-indolo[3,2-c]isoquinolin-5-on-6-yl)methyl-1,3,4-oxadiazole-2-thiones 10a-c , also ethyl (8-substituted-11H-indolo[3,2-c]isoquinolin-5-ylthio)ace-tates 11a-c , (8-substituted-11Hindolo[3,2-c]isoquinolin-5-ylthio)acetyl hydrazides 12a-c , 3,5-disubstituted-pyrazoles 13a-c and 14a-c , 3-substituted-pyrazol-5-ones 15a-c and 5-(8-substituted-11H-indolo[3,2-c]isoquin-olin-5-yl)thiomethyl-1,3,4-oxadiazole-2-thiones 16a-c is described.