8‐Fluoro‐4‐hydroxy‐1H‐[1,2,4]triazino[4,5‐a]quinoline‐1,6(2H)‐dione: Synthesis and reactivity

A simple and versatile methodology to synthesise 4‐hydroxy‐1H‐[1,2,4]triazino[4,5‐a]quinoline‐1,6(2H)‐dione from methyl 6‐fluoro‐4‐oxo‐1,4‐dihydro‐2‐quinolinecarboxylate has been developed. It involves car‐bohydrazide formation followed by a condensation with triphosgene to form the fused [1,2,4]triazino ring. In addition, the reactivity of the [1,2,4]triazino ring has been studied.     

Synthesis of novel fused tricyclic quinolones: 4a,5‐Dihydro‐1H‐[1;2,4]triazino[1,6‐a]quinoline‐2,4,6(3H)‐triones

A versatile methodology to build the 1H‐[1,2,4]triazino[1,6‐a]quinoline‐2,4,6(3H)‐trione structure from methyl 6‐fluoro4‐oxo‐1,4‐dihydro‐2‐quinolinecarboxylate was developed. The method involves an N‐ami‐nation followed by condensation of an aroyl isocyanate to form an alpha semicarbazidocarboxylate that readily cyclizes to the fused [1,2,4]triazino ring under ammonia/ethanol condition. Also, the reactivity of the [1,2,4]triazino ring thus obtained was studied.     

Cyclocondensation reaction of heterocyclic carbonyl compounds . The direction of competitive cyclocondensation between carbonyl groups of 6‐azauracile and 1,2‐dihydro‐quinoxalin‐2‐one cycles

In the article the study of cyclocondensation of 3‐[2‐amino‐3‐(3,5‐dioxo‐2,3,4,5‐tetrahydro[1,2,4]‐triazme‐6‐yl)phenyl]‐2,3‐dihydro‐quinoxalin‐2‐one 5 is described and it was found, that the reaction does not proceed by both possible directions, but only cyclization with the carbonyl group of 6‐azauracile cycle proceeds. The 6‐(3‐oxo‐3,4‐dihydro‐quinoxaline‐2‐yl)‐4H‐2,3‐dihydro[1,2,4]triazino[5,6‐b]indol‐3‐one 6 was formed in this way. This course of cyclocondensation was confirmed by the fact, that the product 6 , mentioned above, is quite different from isomeric compound 7 , prepared unambiguously by condensation of 7‐(6‐azauracile‐5‐yl)isatine 8 with o‐phenylenediamine.     

Synthesis and reactions of 11H‐benzo[b]pyrano[3,2‐f]indolizines an pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolines

2‐Methyl‐3H‐indoles 1 cyclize with two equivalents of ethyl malonate 2 to form 4‐hydroxy‐11H‐benzo[b]pyrano[3,2‐f]indolizin‐2,5‐diones 3, whereas 2‐mefhyl‐2,3‐dihydro‐1H‐indoles 9 give under similar conditions regioisomer 8‐hydroxy‐5‐methyl‐4,5‐dihydro‐pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolin‐7,10‐diones 10 . The pyrone rings of 3 and 9 can be cleaved either by alkaline hydrolysis to give 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 4 or 5‐acetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo‐[3,2,1‐ij]quinolin‐4‐ones 11 , respectively. Chlorination of 3 and 9 with sulfurylchloride gives under subsequent ring opening 7‐dichloroacetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 5 or 5‐dichloracetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 12 . The dichloroacetyl group of 5 can be reduced with zinc to 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 7. Treatment of the acetyl compounds 4, 7 and 11 with 90% sulfuric acid cleaves the acetyl group and yields 8‐hydroxy‐10H‐pyrido[1,2‐a]‐indol‐6‐ones 6 and 8 , and 6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 13 . Reaction of dichloroacetyl compounds 12 with sodium azide yields 6‐hydroxy‐2‐methyl‐5‐(1H‐tetrazol‐5‐ylcarbonyl)‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 14 via intermediate geminal diazides.     

Synthesis of ethyl 6‐aryl‐4‐oxo‐4,6‐dihydro‐1(12)(13)h‐pyrimido‐[2′,1′:4,5][1,3,5]triazino[1,2‐a]benzimidazole‐3‐carboxylates

The synthesis of ethyl 6‐aryl‐4‐oxo‐4,6‐dihdro‐1(12)(13)H‐pyrimido[2′,1′:4,5][1,3,5]triazino[1,2‐a]‐benzimidazole‐3‐carboxylates ( 4a‐p ) was described via pyrimidine ring annulation to 4‐aryl‐3,4‐dihydro[1,3,5]triazino[1,2‐a]benzimidazole‐2‐amines ( 2a‐p ) which were obtained from 2‐guanidinobenzimidazole ( 1 ). Tautomerism in the prepared compounds was investigated using nmr spectroscopy. Compounds 2a‐p were found to be present in dimethyl sulfoxide solution predominantly as 3,4‐dihyhydro tautomeric form. Compounds 4a‐p existed in dynamic equilibrium of 1‐, 12‐ and 13H‐forms. It was found that methylation of 4a‐d led to 13‐methyl substituted derivatives 9a‐d exclusively.     

Preparation of 2,3‐dihydro‐1H,5H‐pyrido[3,2,1‐ij]quinoline‐1,5‐dione derivatives

The 2,3‐dihydro‐7‐methyl‐1H,5H‐pyrido[3,2,1‐ij]quinoline‐1,5‐dione derivatives 9 and 10 were prepared from 3‐(5,7‐dimethoxy‐4‐methyl‐2‐oxo‐2H‐quinolin‐1‐yl)propionitrile ( 6 ). Cyclodehydration of the amide 8 gave 1,2‐dihydro‐7,9‐dimethoxy‐6‐methylpyimido[1,2‐a]quinolin‐3‐one ( 11 ).     

Synthesiss of novel 3‐(2‐thienyl)‐1,2‐diazepino[3,4‐b]quinoxalines with algicidal activity

The reaction of the quinoxaline N‐oxide 1 with thiophene‐2‐carbaldehyde gave 6‐chloro‐2‐[1‐methyl‐2‐(2‐thienylmethylene)hydrazino]quinoxaline 4‐oxide 5 , whose reaction with 2‐chloroacrylonitrile afforded 8‐chloro‐2,3‐dihydro‐4‐hydroxy‐1‐methyl‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]quinoxaline‐5‐carbonitrile 6 . The reaction of compound 6 with various alcohols in the presence of a base effected alcoholysis to provide the 5‐alkoxy‐8‐chloro‐2,3,4,6‐tetrahydro‐1‐methyl‐4‐oxo‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]‐quinoxalines 7a‐d . The reaction of compounds 7a and 7b with diethyl azodicarboxylate effected dehydrogenation to give the 5‐alkoxy‐8‐chloro‐4,6‐dihydro‐1‐methyl‐4‐oxo‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]‐quinoxalines 8a and 8b , respectively. Compounds 8a and 8b were found to show good algicidal activities against Selenastrum capricornutum and Nitzchia closterium.     

Reactions of 4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidines with α,β‐unsaturated carbonyl compounds

The reaction of 5,7‐diphenyl‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidine ( 1 ) with α,β‐unsaturated carbonyl compounds 2a‐f led to the formation of the alkylated heterocycles 3a‐f (Figure 1). However, the reaction of 5‐methyl‐7‐phenyl‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidine ( 5 ) with 2a‐c yielded under the same conditions the triazolo[5,1‐b]quinazolines 6a‐c (Figure 3). In this case, the alkylation is followed by a cyclocondensation. The structure elucidation of the products is based on ir, ms, ¹H and ¹³C nmr measurements and on an X‐ray diffraction study.     

The Pseudo‐Michael Reaction of 2‐Hydrazinylidene‐1‐Arylimidazolidines with Diethyl Ethoxymethylenemalonate

The pseudo‐Michael reaction of 2‐hydrazinylidene‐1‐arylimidazolidines with diethyl ethoxymethylenemalonate (DEEM) was investigated. The reaction yields the chain adduct, namely diethyl{[2‐(1‐arylimidazolidin‐2‐ylidene)hydrazinyl]methylidene}propanedioates. This is contrary to the pseudo‐Michael reaction of DEEM with 1‐aryl‐4,5‐dihydro‐1H‐imidazol‐2‐amines that does not allow isolation of chain derivatives and leads to cyclic imidazo[1,2‐a]pyrimidine derivatives while even at thermodynamic control. At first cyclization of diethyl{[2‐(1‐arylimidazolidin‐2‐ylidene)hydrazinyl]methylidene}propanedioates leads to ethyl 1‐aryl‐5(1H,8H)oxo‐2,3‐dihydro‐imidazo[2,1‐c][1,2,4]triazepine‐6‐carboxylates. 1,5‐Sigmatropic shift, following the cyclization, caused isomerization of 5(1H,8H)oxo‐2,3‐dihydro‐imidazo[2,1‐c][1,2,4]triazepine‐6‐carboxylates to ethyl 1‐aryl‐5(1H)hydroxy‐2,3‐dihydroimidazo[2,1‐c][1,2,4]triazepine‐6‐carboxylates. Presence of both isomers in the reaction product was detected in the NMR spectra. The structure of all the compounds was confirmed with spectroscopic studies (¹H NMR and MS). The structure of diethyl{[2‐(1‐phenylimidazolidin‐2‐ylidene)hydrazinyl]methylidene}propanedioate was also confirmed by X‐ray crystallography. In the addition reaction, thermodynamics and HOMO–LUMO orbitals of the reactants were studied by using quantum chemical calculations.     

Diastereoselective Synthesis of (Z)‐6‐(2‐Oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐diones

Two efficient and diastereoselective procedures for the synthesis of (Z)‐6‐(2‐oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐diones by aldol‐crotonic condensation of 1,3‐dimethyl‐3a,9a‐diphenyl‐3,3a,9,9a‐tetrahydroimidazo[4,5‐e]thiazolo[3,2‐b]‐1,2,4‐triazin‐2,7(1H,6H)‐dione with isatins under acidic or basic catalysis are reported. Isomerization in (Z)‐7‐(1‐allyl‐2‐oxo‐1,2‐dihydro‐3H‐indol‐3‐ylidene)‐1,3‐dimethyl‐3a,9a‐diphenyl‐1,3a,4,9a‐tetrahydroimidazo[4,5‐e]thiazolo[2,3‐c]‐1,2,4‐triazin‐2,8(3H,7H)‐dione was observed under basic conditions.     

Formylation of 4,7‐Dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidines Using Vilsmeier–Haack Conditions

Formylation of 5‐methyl‐7‐phenyl‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidine 1a using Vilsmeier–Haack conditions yields 5‐methyl‐7‐phenyl‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidin‐6‐ylcarbaldehyde 3a . 5,7‐Diaryl‐4,7‐dihydro‐1,2,4‐triazolo[1,5‐a]pyrimidines 1b , 1c in this reaction apart from formylation undergo recyclization into 5‐aryl‐1,2,4‐triazolo[1,5‐a]pyrimidin‐6‐ylmethane derivatives 4b , 4c , 5b , 5c , and 6 . The structure of the synthesized compounds was determined on the basis of NMR, IR, and MS spectroscopic data and confirmed by the X‐ray analysis of the 6‐(ethoxy‐phenyl‐methyl)‐5‐phenyl‐[1,2,4]triazolo[1,5‐a]pyrimidine 6 , 5‐phenyl‐6‐(1‐phenyl‐vinyl)‐[1,2,4]triazolo[1,5‐a]pyrimidine 11 , and 7‐phenyl‐6‐(1‐phenyl‐vinyl)‐[1,2,4]triazolo[4,3‐a]pyrimidine 12 .     

Synthesis of Some New Nitrogen Bridge‐head Triazolopyridines,Pyridotriazines, and Pyridotriazepines Incorporating 6‐Methylchromone Moiety

Some new triazolo[1,5‐a]pyridines, pyrido[1,2‐b][1,2,4]triazines, and pyrido[1,2‐b][1,2,4]triazepines incorporating 6‐methylchromone moiety were prepared from the reaction of 1,6‐diamino‐4‐(6‐methyl‐4‐oxo‐4H‐chromen‐3‐yl)‐2‐oxo‐1,2‐dihydropyridine‐3,5‐dicarbonitrile ( 4 ) with some electrophilic reagents.     

A convenient route to pyridones,pyrazolo[2,3‐a]pyrimidines and pyrazolo[5,1‐c]triazines incorporating antipyrine moiety

Condensation of 4‐aminoantipyrine with ethyl acetoacetate, ethyl benzoylacetate, and ethyl cyanoacetate furnished the corresponding ethyl 3‐(1,2‐dihydro‐1,5‐dimethyl‐2‐phenyl‐3‐oxo‐3H‐pyrazol‐4‐yl)aminoacrylate and 2‐cyano‐N‐[(1,2‐dihydro‐1,5‐dimethyl‐2‐phenyl‐3‐oxo‐3H‐pyrazol‐4‐yl)]acetamide derivatives. The aminoacrylates derivatives react with acetonitrile and sodium hydride to give 2‐amino‐6‐methyl‐1‐(1,2‐dihydro‐1,5‐dimethyl‐2‐phenyl‐3‐oxo‐3H‐pyrazol‐4‐yl)‐4‐pyridone. Reaction of the cyanoacetamide derivative with dimethylformamide‐dimethylacetal (DMF‐DMA) afforded 2‐cyano‐N‐[1,2‐dihydro‐1,5‐dimethyl‐2‐phenyl‐3‐oxo‐pyrazol‐4‐yl]‐2‐(N,N‐dimethylamino)methylene acetamide in high yield. Treatment of the latter with 5‐aminopyrazole derivatives afforded the corresponding pyrazolo[2,3‐a]pyrimidines. 2‐cyano‐N‐[(1,2‐dihydro‐1,5‐dimethyl‐2‐phenyl‐3‐oxo‐3H‐pyrazol‐4‐yl)]acetamide also reacts with heterocyclic diazonium salts to give the corresponding pyrazolo[5,1‐c]‐1,2,4‐triazine derivatives. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:508–514, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20046     

Synthesis of 2‐amino‐s‐triazino[1,2‐a]benzimidazoles as potential antifolates from 2‐guanidino‐ and 2‐guanidino‐5‐methylbenzimidazoles

The syntheses of 2‐amino‐s‐triazino[1,2‐a]benzimidazoles from 2‐guanidinobenzimidazoles were successfully carried out by a ring annelation reaction. The regiochemistry of the ring closure of 5‐methyl‐2‐guanidinobenzimidazole with diethyl azodicarboxylate, aldehydes, acetone, diethyl ethoxymethylenemalonate and orthoesters, leading to the formation of s‐triazine ring was studied. High regioselectivity was not observed in any of these reactions. However, the synthesis of s‐triazino[1,2‐a]benzimidazole system was found to be more regioselective than its 3,4‐dihydro analogue. NOESY experiment indicated that the compound, 2‐amino‐4,4‐dimethyl‐3,4‐dihydro‐s‐triazino[1,2‐a]benzimidazole existed predominantly as the 3,4‐dihydro tautomer in dimethyl sulfoxide. It was found to inhibit bovine dihydrofolate reductase with IC₅₀ 10.9 μM.     

An Efficient Synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one Derivatives via Multi‐Component Approach

An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.     

Strategy to Construct Stair‐Shaped Partially Reduced Naphtho[1,2‐b]pyrano[2,3‐d]oxepines and Dinaphtho[1,2‐b,d]oxepines

A concise and efficient base‐induced synthesis of stair‐shaped, 4‐methylthio‐2‐oxo‐5,6‐dihydro‐2H‐naphtho[1,2‐b]pyran[2,3‐d]oxepine‐3‐carbonitriles ( 3 ) has been delineated by the reaction of 3,4‐dihydronaphtho[1,2‐b]oxepin‐5(2H)‐one ( 1 ) and methyl 2‐cyano‐3,3‐dimethylthioacrylate in DMSO using powdered KOH as a base at room temperature. Amination of 3 has been achieved by reaction with secondary amine in ethanol at reflux temperature to yield 4‐sec‐amino‐2‐oxo‐5,6‐dihydro‐2H‐naphtho[1,2‐b]pyran[2,3‐d]oxepine‐3‐carbonitriles ( 4 ). Reaction of 3 with aryl methyl ketone ( 5 ) in DMSO at room temperature using powdered KOH as a base produced stair‐shaped 5‐aryl‐7,8‐dihydro‐1,4‐dioxa‐2,3‐dioxodinaphtho[1,2‐b,d]oxepine ( 6 ) in good yields. However, reaction of 6‐aryl‐2H‐pyran‐2‐one‐3‐carbonitrile ( 8 ) with 3,4‐dihydronaphtho[1,2‐b]oxepin‐5(2H)‐one ( 1 ) did not give similar product, but in lieu 4‐aryl‐5,6‐dihydronaphtho[1,2‐b]oxepino[4,5‐b]pyran‐2‐ylidene)acetonitrile ( 9 ) was isolated and characterized.     

Synthesis and reactivity of 1‐amino‐4‐methyl‐3,4‐dihydro‐5H‐pyrazolo[3′,4′:4,5]pyrimido[1,6‐a]benzoimidazolo‐5‐one

Pyrimido[2“,1”:5′,6′]pyrazolo[3′,4′:4,5]‐pyrimido[1,6‐a]benzoimidazoloe‐2,8(1H,7H)‐diones, and [1,2,4]‐triazino‐[3“,4”:5′,6′]pyrazolo[3′,4′:4,5]pyrimido[1,6‐a]benzimidazol‐8(7H)‐ones were synthesized in a good yields via 1‐amino‐4‐methyl‐3,4‐dihydro‐5H‐pyrazolo[3′,4′:4,5]pyrimido[1,6‐a]benzoimidazolo‐5‐one and the appropriate active methylene compounds. Structures of the newly synthesized compounds were elucidated on the basis of elemental analyses, spectral data, and alternative synthesis methods whenever possible.     

Reaction of cyclic imidates with α,β‐unsaturated esters: Synthesis of new pyrrolo[2,1‐b]‐1,3‐oxazine and pyrido[2,1‐b]‐1,3‐oxazine derivatives

The cycloaddition reaction of cyclic imidates, 2‐benzyl‐5,6‐dihydro‐4H‐1,3‐oxazines 1a , 1b , 1c , 1d , 1e , 1f , with dimethyl acetylenedicarboxylate 2 , trimethyl ethylenetricarboxylate 4 , or dimethyl 2‐(methoxymethylene)malonate 6 afforded new fused heterocyclic compounds, such as methyl (6‐oxo‐3,4‐dihydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐ylidene)acetates 3a , 3b , 3c , 3d , 3e , 3f (71–79%), dimethyl 2‐(6‐oxo‐3,4,6,7‐tetrahydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐yl)malonates 5b , 5c , 5d , 5e , 5f (43–71%), or methyl 6‐oxo‐3,4‐dihydro‐2H,6H‐pyrido[2,1‐b]‐1,3‐oxazine‐7‐carboxylates 7a , 7b , 7c , 7d , 7e , 7f (32–59%), respectively. In these reactions, 1a , 1b , 1c , 1d , 1e , 1f (cyclic imidates, iminoethers) functioned as their N,C‐tautomers (enaminoethers) 2 to α,β‐unsaturated esters 2 , 4, and 6 to give annulation products 3 , 5 , and 7 following to the elimination of methanol, respectively. J. Heterocyclic Chem., (2011).     

Rapidly and Highly Yielded Synthesis of Pyrimidine,Dihydropyrimidinone, and Triazino[2,1‐b]quinazolin‐6‐ones Derivatives

The reaction of 4‐oxo‐3,4‐dihydroquinazolinyl‐2‐guanidine 1 with several active methylene compounds has revealed formation of the corresponding hydropyrimidine and dihydropyrimidnone (DHPMs) derivatives via cycloaddition reaction mechanism. Satisfactory results were obtained with good yields, short time, and simplicity in the experimental procedure. Reaction with ketones in DMF proceeded via (5+1) heterocyclization and resulted in the formation of 2‐amino‐4‐(het)aryl‐4,6‐dihydro‐1(3)(11)H‐[1,3,5]triazino[2,1‐b]quinazolin‐6‐ones 8 , 9 , 10 , 11 , 12 , 13 , respectively. All compounds have been characterized based on IR, ¹H‐NMR, and mass spectrum.     

A simple and efficient synthesis of novel N,N′‐bis (1H‐pyrrol‐1‐yl)‐1‐[2‐(2‐aryl‐5‐methyl‐3‐oxo‐2,4‐dihydro‐3H‐1,2,4‐triazol‐4‐yl)ethyl]‐1H‐1,2,3‐triazole‐4,5‐dicarboxamides

One‐pot reaction of 3‐aryl‐5‐methyl‐1,3,4‐oxadiazolin‐2‐ones 1a‐g with ethanolamine yielded the 4‐(2‐hydroxyethyl)‐2‐aryl‐5‐methyl‐2,4‐dihydro‐3H‐1,2,4‐triazolin‐3‐ones 2a‐g which were converted to the azido compounds 6a‐g . These azides on 1,3‐dipolar cycloaddition with DMAD afforded the dimethyl‐1‐[2‐(2‐aryl‐5‐methyl‐3‐oxo‐1,2,4‐triazol‐4‐yl)ethyl]‐1H‐1,2,3‐triazol‐4,5‐dicarboxylates 7a‐g which on conversion to bishydrazides 8a‐g and further cyclisation with 2,5‐hexanedione afforded the title compounds 9a‐g . This new short route for the so far unkown bis‐(triazolinone‐triazole)ethanes involves mild and convergent 1,3‐dipolar cycloaddition reaction yielding overall good yields of the products.