Synthesis and reactivity of thieno[2,3-b]quinoline derivatives (Part II)

As a continuation of our previous review entitled “Vilsmeier-Haack cyclisation as a facile synthetic route to thieno[2,3-b]quinolines (Part I).” This review describes the methods of preparation and the chemical reactivity of thieno[2,3-b]quinolines, which might show interesting biological activities.     

Copper(II)–neocuproine reagent for spectrophotometric determination of captopril in pure form and pharmaceutical formulations

A simple, rapid, sensitive and accurate spectrophotometric method for the determination of captopril in pure form and pharmaceutical formulations is developed. The procedure is based on the reaction of copper(II) with captopril in the presence of neocuproine (NC) (2,9-dimethyl-1,10-phenanthroline) reagent in acetate buffer at pH 5.0. Copper(II) is reduced easily by captopril to Cu(I)–neocuproine complex, which shows an absorption maximum at 448 nm. Beer’s law was obeyed in the concentration range 0.3–3.0 μg mL^?1 with a minimum detection limit (LOD) of 0.039 μg mL^?1 and a quantification limit (LOQ) of 0.129 μg mL^?1. For more accurate results, Ringbom optimum concentration ranges was 0.5–2.7 μg mL^?1. The apparent molar absorbtivity and Sandell sensitivity were calculated. The validity of the proposed method was tested by analyzing the pure and pharmaceutical formulations and compared well with those obtained by the official method and demonstrated good accuracy and precision.     

Cyanoacetamide in heterocyclic chemistry: Synthesis,antitumor and antioxidant activities of some new benzothiophenes

Cyanoacylation of 2‐amino‐tetrahydrobenzothiophene‐3‐carboxylate ethyl ester with 3‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐3‐oxopropanenitrile afforded cyanoacetamide 2 . The later was utilized as key intermediate for the synthesis of 3‐substituted 2‐iminocoumarins 3 , 4 , 5 , 6 and acrylamides 7a , b via Knoevenagel condensation with 2‐hydroxy‐1‐naphthaldehyde; 2‐hydroxybenzaldehyde; 1‐nitrosonaphthalen‐2‐ol; 7‐hydroxy‐5‐methoxy‐2‐methyl‐4‐oxo‐4H‐chromene‐6‐carbaldehyde; 4‐dimethylamino‐benzaldehyde; and 4‐piperidin‐1‐yl‐benzaldehyde in EtOH/piperidine. The derivatives 7a , b did not afford the pyrazoles 8a , b upon treating with phenyl hydrazine. Furthermore, coupling of 2 with 4‐amino‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one and 4,6‐dimethyl‐1H‐pyrrolo[2,3‐b]pyridin‐3‐amine afforded the hydrazone derivatives 9 and 10 , respectively. The later derivative 10 was cyclized in acetic acid to afford the pyridopyrazolotriazine 11 . Finally, 2 was treated with dimethylformamide‐dimethylacetal (DMF‐DMA) to afford the dimethylaminoacrylamide 12 which underwent transamination with 4,6‐dimethyl‐1H‐pyrrolo[2,3‐b]pyridin‐3‐amine to afford the pyrazole 13 . Cyclization of compound 13 in acetic acid or pyridine was unsuccessful. The antitumor and antioxidant activities of the synthesized products were evaluated; several were found to exhibit promising antioxidant activities. J. Heterocyclic Chem., (2011).     

2-Cyano-N-(4-sulfamoylphenyl) Acetamide as a Synthon in Heterocyclic Synthesis

This review describes the synthesis and reactions of 2-cyano-N-(4-sulfamoylphenyl) acetamide as a building block for the synthesis of polyfunctionalized heterocyclic compounds including its synthesis, reactivity, and reaction.     

Chemistry of 2-Amino-3-cyanopyridines

This review presents a systematic and comprehensive survey of the method of preparation and the chemical reactivity of 2-amino-3-cyanopyridines. The target compounds are important intermediates for the synthesis of a variety of synthetically useful and novel heterocyclic systems.     

Time-shift scheduling-fair scheduling of flows in high-speednetworks

We present a scheduling protocol, called time-shift scheduling, to forward packets from multiple input flows to a single output channel. Each input flow is guaranteed a predetermined packet rate and an upper bound on packet delay. The protocol is an improvement over existing protocols because it satisfies the properties of rate-proportional delay, fairness, and efficiency, while existing protocols fail to satisfy at least one of these properties. In time-shift scheduling each flow is assigned an increasing timestamp, and the packet chosen for transmission is taken from the flow with the least timestamp. The protocol features the novel technique of time shifting, in which the scheduler's real-time clock is adjusted to prevent flow timestamps from increasing faster than the real-time clock. This bounds the difference between any pair of flow timestamps, thus ensuring the fair scheduling of flows     

Synthesis and cytotoxic activity of some new heterocycles incorporating cyclohepta[b]thiophene-3-carboxamide derivatives

A series of 2-amino-5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophene-3-carboxamide-heterocyclic hybrids were synthesized, characterized and their cytotoxic potencies were assessed on four human cell lines. Cyanoacetamide derivative ( 5 ) was used as the key synthetic intermediate for the synthesis many derivatives in this study, derivatives 9 , 11 , 12 were formed by coupled compound 5 with different aryl/heteryl diazonium chlorides, Gewald reaction and Knoevenagel condensation were used for synthesis derivatives 13 , 14 , 16 by treated cyanoacetamide ( 5 ) with different reagents. In another route, compound 5 treated with phenyl isothiocyanate give thiocarbamoyl derivative ( 7 ) which used as intermediate underwent oxidative cyclization with different moieties to offer the corresponding thiazoles and thiophene 18 , 19 , 20 , 21 , respectively. in vitro cytotoxic activity of prepared compounds were tested against four human tumor cell lines. The result revealed that compound 11a displayed promising cytotoxic activity against HepG2, HCT-116, MCF-7, and PC3 cancer cell lines comparing to the positive control (Doxorubicin).     

Assessment of Acrylamide Degradation Potential of Pseudomonas aeruginosa BAC-6 Isolated from Industrial Effluent

Acrylamide finds diverse industrial applications but is considered an environmental threat because of its neurotoxic, carcinogenic, and teratogenic effects. Certain bacteria enzymatically degrade acrylamide to acrylic acid and ammonia. The present investigation was carried out to isolate and identify an acrylamide-degrading bacterium from industrial effluent. Bacterial growth and extent of acrylamide degradation in the presence of different acrylamide concentrations, nutrients, varied range of pH, and temperature were analyzed. Among the eight acrylamide-degrading isolates, isolate BAC-6 demonstrated the highest degradation, and based upon the partial 16S rDNA sequencing, it was identified as Pseudomonas aeruginosa. P. aeruginosa BAC-6 grew over a wide range of acrylamide concentrations, but the highest degradation was recorded at 500 mg/L concentration with concomitant cell growth. Among the carbon supplements, mannitol supported the highest growth and degradation. Maximum degradation was reported at neutral pH. A mesophilic temperature range (25–40 °C) facilitated conducive bacterial growth followed by degradation. The highest degradation and bacterial growth were observed at 30 and 35 °C, respectively. Thus, it could be inferred from the present investigation that cultural conditions strongly affected the degradation potential of P. aeruginosa BAC-6 and advocated the utilization of the isolate in bioremediation of sites polluted with acrylamide.     

Synthesis of Some New Fused and Binary 1,3,4‐Thiadiazoles as Potential Antitumor and Antioxidant Agents

Annulations of 2‐amino‐1,3,4‐thiadiazole ( 1 ) with α,β‐unsaturated carbonyl compounds 2 , 5 , and 9 afforded thiadiazolo[3,2‐a]pyrimidin 3 , benzamide 7 , and bis‐pyrazole derivative 11 . Cyclization of benzamide 7 with POCl₃ gave binary imidazole derivative 8 . Moreover, alkylation of 1 with 2‐bromo‐1‐(2H‐chromen‐3‐yl) ethanone ( 9 ) followed by cyclization gave imidazo[2,1‐b]‐1,3,4‐thiadiazole derivative 15 . Multicomponent reaction of 1 with heterocyclic and/or aromatic aldehyde and thioglycolic acid afforded the corresponding thiazolidinones 17 and 19 . Finally, a one‐pot synthesis of 1 with isatin and thiosemicarbazide furnished the spirotriazole 20 . The newly synthesized compounds were evaluated as antitumor agents.     

1-Phenyl-2-thiocyanatoethanone as Synthons in Heterocyclic Synthesis

This review presents a systematic and comprehensive survey of the method of preparation and the chemical reactivity of 1-phenyl-2-thiocyanatoethanone. The target compound is an important intermediate for the synthesis of a variety of synthetically useful and novel heterocyclic systems.