1,2,4,5-Tetrazine-3,6-dicarboxylate

Tetrazine-3,6-dicarboxylic acid, 1,6-dihydro-diethyl ester... 

Tetrazine-3,6-dicarboxylic acids decarboxylation, 3, 555 electronic spectra, 3, 540... 

The isomeric pyridazino[4,5-6]azepine 19 is obtained directly during the decomplexation of the [4 + 2] adduct 17 formed from tricarbonyl(ethyl +17/-azepine-l-carboxylate)iron and 1,2,4,5-tetrazine-3,6-dicarboxylate, with trimethylamine A-oxide.113 Surprisingly, decomplexation of adduct 17 with tetrachloro-l,2-benzoquinone yields only the dihydro derivative 18 (71 %), aromatization of which is achieved in high yield with trimethylamine A-oxide in refluxing benzene. 

Equimolecular amounts of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate and 1,2-diphenylcyclopropene in CH2C12 at 20 LC gave the diazanorcaradiene la (72% mp 172— 174CC), a toluene solution of which was refluxed to afford the diazepinc 2a (50% mp 177-178T7). 

The [4+2] cycloaddition of dimethyl-1,2,4,5-tetrazine-3,6-dicarboxylate 41 with ketene A, O-acetals or cyanamide yielded tetrafunctionalized pyridazines 42 or 1,2,4-triazine 43 respectively. Treatment of 42-43 with zinc dust in AcOH afforded pyrrole 44 or imidazole 45 derivatives <06S1513>. 

Preparation and Diels-Alder Reaction of a Reactive, Electron-Deficient Heterocyclic Azadiene Dimethyl 1,2,4,5-Tetrazine-3,6-Dicarboxylate. 1,2-Diazine and Pyrrole Introduction. 

Tautomerism of tetrazines was investigated by ID 15N INADEQUATE.85 Dimethyl dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate can exist either in 1,2- (8) or... 

Dimethoxy-l-trimethylsilyloxy-l, 3-butadiene. 1,2-Dimethoxy-1 -trimethylsily-loxy-l,3-pentadiene. Dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate. 1 -Methoxy-... 

Substituted 1,2,4-triazines and 1,2,4,5-tetrazines are known to undergo [2-1-4] cycloaddition with inverse electron demand when reacted with alkenes. The primary bicyclic product loses nitrogen to give dihydropyridines and dihydropyridazines, respectively. The reaction of methylenecyclopropane with dimethyl-1,2,4,5-tetrazine-3,6-dicarboxylate at room temperature gave the spiro-dihydropyridazine 2 in 80% yield. ... 

S. Dihydro-1,2,4,5-tetrazine-3,6-dicarboxylic acid. A 2-L, three-necked, round-bottomed flask is equipped with an overhead stirrer and a 100-mL addition funnei. Disodium dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate (90.37 g 0.42 mol) in 100 mL of water and 100 g of crushed ice are added. The resulting slurry is cooled with an ice/sodium chloride bath and a solution of concentrated hydrochloric acid (84 mL of 36-38%) is added dropwise with stirring over 45 min. The reaction mixture is washed five times with 200 mL of dry ether and the ether layer is decanted. The product is immediately collected by filtration using a BOchner funnel. Drying the collected solid at room temperature under reduced pressure affords 51.6-53.06 g (72-74%) of dihydro-... 

This approach to 1,2-diazine and pyrrole introduction based on the inverse electron demand Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate complements the [4 + 2] cycloaddition reactions of a range of electron-deficient heterocyclic azadienes which permits the divergent preparation of a range of heterocyclic agents employing a common dienophile precursor, Scheme I. 

Dimethyl 1,2,4,5-tetrazlne-3,6-dicarboxylate s-Tetrazine-3,6-dicarboxylic acid, dimethyl ester (8) 1,2,4,5-Tetrazine-3,6-dicarboxylic acid, dimethyl ester (9) (2166-14-5)... 

DIHYDROPYRIDINE EQUIVALENT, 70, 54 Dihydroquinidine, benzoate ester, 70, 49 DIhydroquinIdIne 4-chlorobenzoate, 70, 47 Dihydroquinidine, 2-naphthoate ester, 70, 49 Dihydro-1,2,4,5-tetrazine-3,6-dicarboxylate, 70, 80 Dilsobutylaluminum hydride, 70, 20... 

PREPARATION AND DIELS-ALDER REACTION OF A REACTIVE, ELECTRON-DEFICIENT HETEROCYCLIC AZADIENE DIMETHYL 1,2,4,5-TETRAZINE-3,6-DICARBOXYLATE. 1,2-DIAZINE AND PYRROLE INTRODUCTION... 

The submitters employed, without purification, thionyl chloride obtained from Fisher Scientific Company. The procedure should be performed in a well-ventilated hood since thionyl chloride Is a lachrymator. The yield of dimethyl ester was found to be lower in instances when the thienyl chloride-methanol solution was not allowed to stir (30 min, -30°C) prior to the addition of dihydro-1,2,4,5-tetrazine-3,6-dicarboxylic acid. 

The procedure describes the preparation and use of a reactive, electron-deficient heterocyclic azadiene suitable for Diels-Alder reactions with electron-rich, unactivated, and electron-deficient dienophiles. Dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate, because of its electron-deficient character, is ideally suited for use in inverse electron demand (LUMOdiene-controlled) Diels-Alder reactions. Table I and Table II detail representative examples of the reaction of dimethyl 1,2,4,5-tetrazine-3.6-... 

Dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate (10a 0.99 g, 5 mmol) and ethyl thioformate (0.45 g, 5 mmol) were heated at reflux in toluene until the red color of the tetrazine disappeared (ca. 110 h). The solvent was then distilled off, the residue boiled several times with hexane, and filtered hot. Lemon-yellow crystals separated on cooling and were recrystallized (anhyd hexane) yield 0.65 g (50%) mp 90-91CC. 

To a suspension of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate (2.0 g, 10 mmol) in anhyd PhCl (50 raL) was added A -,A -dimethy 1 cyanamide (700 mg, 10 mmol) and the mixture heated under reflux with exclusion of moisture until the solution became colorless. The solvent was removed and the residue dissolved in EtOAc. Cooling in a refrigerator afforded the product yield 1.78 g (78%) mp 130°C. 

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