Synthesis and Antibacterial Activity of Certain Fused Azoles and Oxazinones

2‐Phenyl‐4‐benzylidene‐5(4H)‐oxazolones ( 1a‐e) were used as versatile starting materials for the synthesis of fused compounds such as: 4H‐3,1‐benoxazin‐4‐ones (2a,b), imidazo[4,3‐b]benzimidazoles (3,4), imidazo[1,5‐b]1,2,4‐triazoles (5a,b), and 7 .     

Methylated Azoles, 2‐Tetrazenes,and Hydrazines

This report is a summary of our work on energetic materials. Herein, triazole‐, tetrazole‐, 2‐tetrazene‐ and hydrazine‐based energetic compounds are described. An overview of the synthetic methods and of the problematic around the quest of new explosives is given. Hydrogen‐bonding formation and alkylation (methylation) reactions were studied as a mean to decrease the sensitivities towards classical stimuli and increase their thermal and chemical stability. ¹⁵N NMR spectroscopy is a valuable tool for the assignment of the methylation site in keeping with the results of the crystal structure analysis. Lastly, the thermal/chemical stability, sensitivity data and energetic performance of the compounds is described.     

Microwave‐promoted Synthesis of Novel Fused Osthole Analogues

Osthole is a natural coumarin derivative and has a broad scope of biological activities. Two series of novel fused osthole analogues were designed, and synthesized through a highly efficient microwave‐promoted synthetic protocol via the reaction of 4‐hydroxycoumarins and β‐ketoesters. The reaction conditions including solvent, catalyst, microwave power and irradiation time were also optimized. The pyrano[3,2‐c]chromene‐2,5‐diones and furo[3,2‐c]coumarins were obtained through two distinct intramolecular cyclization processes, and the proposed mechanism was also discussed.     

Synthesis of New Fused and Spiro 1,5‐Benzodiazepines

[1,3‐Dihydro‐4‐phenyl(1,5)benzodiazepin‐2‐ylidene]malononitrile 1_a was treated with formaline and some different primary amines to give the corresponding pyrimido(1,5)benzodiazepines 2_a–d . Treatment of compound 1_a with halo reagents yielded the corresponding pyrrolobenzodiazepines 3_a,b . The reaction of compound 1_a with active methylenes, bidentates, S,S‐ and N,S‐acetals afforded the corresponding spiro(1,5)‐benzodiazepines 4_a‐c–8_a,b , respectively.     

An Efficient Synthesis of Some New Isolated and Fused Triazole Derivatives

A facile and efficient route to 5‐hydrazinyl‐3‐phenyl‐3H‐[1,2,4]triazole 2 from the reaction of triazol‐3‐one 1 and hydrazine hydrate is described. In addition, the formation of isolated and fused triazole derivatives was prepared via reaction of 2 with some selected electrophilic reagents in basic medium.     

CuI/8‐Hydroxyquinalidine Promoted N‐Arylation of Indole and Azoles

An efficient catalytic system of CuI/8‐hydroxyquinalidine was developed for the coupling of aryl iodides and indole as well as some azoles. The reaction could be carried out at 90°C under the condition of relatively low catalyst loading, affording various N‐arylindoles and N‐aryl azoles in good yields. The functionalized and hindered aryl iodides were suitable substrates for this transformation.     

Pentacene‐Fused Diporphyrins

In this work, we report the synthesis, spectroscopic characterization, and theoretical analysis of a linearly conjugated pentacene‐fused porphyrin dimer and cross‐conjugated quinone‐fused dinaphtho[2,3]porphyrins. These multichromophoric systems display non‐typical UV‐visible absorptions of either porphyrins or pentacenes/quinones. UV‐visible, emission and magnetic circular dichroism (MCD) spectroscopy suggest strong electronic interactions among the multichromophores in the system. DFT calculations revealed the delocalization of the HOMOs and LUMOs spanning the entire dimer and linker assembly. The pentacene‐fused porphyrin dimer is significantly more stable than both the corresponding pentacene and the heptacene derivatives. The availability of these huge π‐extended and electronically highly interactive multichromophoric systems promises unprecedented electronic and photophysical properties.     

An Efficient Synthesis of Novel Benzo‐Fused Macrocyclic Dilactams

A facile synthetic approach was adopted towards the synthesis of benzo‐fused macrocyclic lactams 2a – 2g via the base‐catalyzed condensation reaction of 2,2′‐[alkanediylbis(oxy)]bis[benzaldehydes] 3a – 3c with N,N′‐substituted bis[2‐cyanoacetamide] derivatives 7a – 7c (Scheme 2). The latter compounds were obtained by the reaction of the appropriate diamines 6a – 6c with ethyl 2‐cyanoacetate ( 4 ). Attempts to prepare the oxaaza macrocycles 2 by alternative pathways were also investigated. The novel pyrazolo‐fused macrocycles 13a and 13b were obtained in 48 and 52% yield, respectively, upon treatment of 2d and 2g with NH₂NH₂?H₂O at 100° (Scheme 4).     

One‐Pot Synthesis of Fused [1,6]Naphthyridine Derivatives via Three‐Component Reaction

A simple, convenient, and eco‐friendly synthetic protocol has been developed via a one‐pot three‐component reaction between 2‐chloroquinoline‐4‐amines, different substituted aromatic aldehydes, and malononitrile using ethanol as reaction medium. Employing this protocol, a series of 5‐chloro‐4‐phenyl benzo[f ][1,6] naphthyridine‐2‐amino‐3‐carbonitrile derivatives were synthesized in an environmentally friendly approach under operational simplicity, short time reactions, easy work‐up procedure, and comparatively high yields. This chemistry provides a convenient and promising synthetic strategy for the construction of the napthyridine skeleton. All synthesized compounds were identified on the basis of their spectral data.     

Synthesis of New Fused and Spiro Heterocyclic Systems from 3,5‐Pyrazolidinediones

4‐Bromo‐1‐phenyl‐3,5‐pyrazolidinedione 2 reacted with different nucleophilic reagents to give the corresponding 4‐substituted derivatives 3–8 . The cyclized compounds 9–11 were achieved on refluxing compounds 3 , 4 or 6_a in glacial acetic acid or diphenyl ether. 4,4‐Dibromo‐1‐phenyl‐3,5‐pyrazolidinedione 12 reacted with the proper bidentates to give the corresponding spiro 3,5‐pyrazolidinediones 13–15 , respectively. The 4‐aralkylidine derivatives 16_a‐c , were subjected to Mannich reaction to give Mannich bases 17_a‐c‐22_a‐c , respectively. 4‐(p‐Methylphenylaminomethylidine)‐1‐phenyl‐3,5‐pyrazolidinedione 23 or 4‐(p‐methylphenylazo)‐1‐phenyl‐3,5‐pyrazolidinedione 29 were prepared and reacted with active nitriles, cyclic ketones and N,S‐acetals to give pyrano[2,3‐c]pyrazole, pyrazolo[4′,3′:5,6]pyrano[2,3‐c]pyrazole, spiropyrazole‐4,3′‐pyrazole and spiropyrazole‐4,3′‐[1,2,4]triazolane derivatives 24–34 , respectively.     

Copper(I)‐Catalyzed Intramolecular Direct C‐Arylation of Azoles with Aryl Bromides

A concise route to access 5H‐imidazo[2,1‐a]isoindole heterofused compounds by copper(I)‐catalyzed intramolecular coupling of non‐activated aryl bromides with azoles is reported. With CuI as catalyst, 1,10‐phenanthroline as ligand, and K₃PO₄ as base, the reactions of 1‐(2‐bromobenzyl)‐1H‐imidazoles in DMF/o‐xylene (1:1, V:V) at 145°C afford the corresponding substituted 5H‐imidazo[2,1‐a]isoindoles in high yields via intramolecular C‐arylation.     

Azoles as Reactive Nucleophiles with Cyclic Perfluoroalkenes

Di‐ and multiazole‐substituted fluorocyclic products ( 2 – 13 ) were readily synthesized in good to high yields. These were synthesized by nucleophilic substitution reactions of perfluorocycloalkenes with azoles (i.e., imidazole, triazole) involving simple reaction procedures. Interestingly, these azoles were later found to be reactive not only with the vinylic, but also with the allylic fluorine atoms. This resulted in the substitution of up to six azoles on the fluorinated rings. Stoichiometry plays a key role in determining the degree of substitution. For comparison, the analogous reactions of N‐substituted 1‐(trimethylsilyl)‐imidazole and 1‐(trimethylsilyl)‐1,2,4‐triazole were also investigated. All of the new compounds were fully characterized by elemental, spectral (¹⁹F, ¹H, ¹³C NMR), and thermal differential scanning calorimetry (DSC) analyses.     

Synthesis and Characterization of Planar Five‐Ring‐Fused Dithiophene‐dione

A series of new organic semiconductors based on s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐4,9‐dione was successfully synthesized and characterized. The electron withdrawing carbonyl group lowers the LUMO energy levels, leading to increased electronegativities, which is beneficial for high photo‐stability in air. The n‐alkyl substituted compounds, 1c and 1d , crystallize with the rigid coplanar systems packed into slipped face‐to‐face π‐stacks. Interestingly, 1c and 1d also show liquid crystalline behaviors, which give highly ordered molecular packing over large area.     

Synthesis and Thermal Behavior of a Fused,Tricyclic 1,2,3,4‐Tetrazine Ring System

This study presents the synthesis and characterization of a fused, tricyclic 1,2,3,4‐tetrazine ring system. The molecule is synthesized in a three‐step process from 5,5′‐dinitro‐bis,1,2,4‐triazole via a di‐N‐amino compound. Oxidation to form the azo‐coupled fused tricyclic 1,2,3,4‐tetrazine is achieved using tert‐butyl hypochlorite as the oxidant. The di‐N‐amino compound and the desired fused tricyclic 1,2,3,4‐triazine display interesting thermal behavior and are predicted to be high‐performance energetic materials.     

Synthesis and Thermal Behavior of a Fused,Tricyclic 1,2,3,4‐Tetrazine Ring System

This study presents the synthesis and characterization of a fused, tricyclic 1,2,3,4‐tetrazine ring system. The molecule is synthesized in a three‐step process from 5,5′‐dinitro‐bis,1,2,4‐triazole via a di‐N‐amino compound. Oxidation to form the azo‐coupled fused tricyclic 1,2,3,4‐tetrazine is achieved using tert‐butyl hypochlorite as the oxidant. The di‐N‐amino compound and the desired fused tricyclic 1,2,3,4‐triazine display interesting thermal behavior and are predicted to be high‐performance energetic materials.     

Synthesis of New Azocompounds and Fused Pyrazolo[5,1‐c][1,2,4]triazines Using Heterocyclic Components

Diazotization of 3‐methyl‐4‐phenyl‐1H‐pyrazol‐5‐amine 1 in hydrochloric acid has been reported to afford the corresponding diazonium salt 2 . The latter underwent azocoupling with a variety of active methylene compounds (barbituric 3a and thiobarbituric 3b acid, 2‐hetarylpyrimidine‐4,6‐dione 6a , 6b , 4‐hydroxy‐6‐methylpyridin‐2(1H)‐one 10a , 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one 10b , 4‐hydroxy‐1‐p‐tolyl‐1H‐pyrazole‐3‐carboxylic acid ethyl ester 14 , 1,3‐thiazolidine‐2,4‐dione 16a , 2‐thioxo‐1,3‐thiazolidin‐4‐one 16b ) to yield new pyrazolylazo derivatives. Fused pyrazolo[5,1‐c][1,2,4]triazines 5 , 9a , 9b , 12 , 13 were obtained by heterocyclization reactions. Copyright © 2013 HeteroCorporation     

Synthesis of Nature‐Inspired Medium‐Sized Fused Heterocycles from Amino Acids

Herein, we describe the synthesis of molecular scaffolds consisting of medium‐sized fused heterocycles using amino acids, which are some of the most useful building blocks used by nature as well as chemists to create structural diversity. The acyclic precursors were assembled by using traditional Merrifield solid‐phase peptide synthesis, and cyclization was carried out through acid‐mediated tandem endocyclic N‐acyliminium ion formation, followed by nucleophilic addition with internal nucleophiles. The synthesis of molecular scaffolds consisting of seven‐, eight‐, and nine‐membered rings proceeded with full stereocontrol of the newly generated stereogenic center in most cases.     

Synthesis and Biological Activity of Some New Diaryl Sulphones Containing Fused Thiazolo Pyrimidines

This paper describes the synthesis of some pyrimido[2,1‐b]benzothiazol‐8‐yl sulphones ( 7, 9, 11, 13, 14, 16 ) starting from bis[2‐aminobenzothiazol‐6‐yl)sulphone 1. Reaction of 1 with acetic anhydride and/or benzoyl chloride gave substituted amino derivatives 2a,b , whereas its reaction with phenacyl bromide and/or p‐chlorophenacyl bromide gave imidazo benzothiazol‐7‐yl sulphones 4a,b .     

Synthesis of New Fused Hetecrocyclic Compounds of Benzpyrid‐4‐One Derivatives and Their Some Biological Activity

A series of fused pyrazolino‐, Isoxazolino‐, Pyrimidino‐, Pyrimidinothino‐, thiazolidinones and β‐lactam incorporating benzpyrid‐4‐one derivatives have been synthesized by different methods of chemical reaction. The prepared compounds were established by universals and modern methods of physical and chemical confirmation.