1,3-Diphenylbenzo[e][1,2,4]triazin-7(1H)-one: selected chemistry at the C-6, C-7 and C-8 positions

1,3-Diphenylbenzo[e][1,2,4]triazin-7(1H)-one (6) reacts with tetracyanoethylene (TCNE) or tetracyanoethylene oxide (TCNEO) to give the deep green 2-[1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-ylidene]propanedinitrile (11) in 17 and 15% yields, respectively. Nucleophiles such as amines, alkoxides, thiols and Grignard reagents all reacted with the 1,3-diphenylbenzotriazinone 6 regioselectively at C-6, while halogenating agents reacted exclusively at C-8. Furthermore, 8-iodo-1,3-diphenylbenzo[e][1,2,4]triazin-7(1H)-one (32) undergoes palladium-catalysed Suzuki-Miyaura and Stille coupling reactions to give 8-aryl- or heteroaryl-substituted benzotriazinones. By combining both the C-6 and C-8 chemistries 1,3,6,8-tetraphenylbenzo[e][1,2,4]triazin-7(1H)-one (42) and 1,3-diphenyl-6,8-di(thien-2-yl)-benzo[e][1,2,4]triazin-7(1H)-one (43) can be prepared. All new compounds are fully characterized.     

Synthesis and molecular structure of 6-amino-3-benzylmercapto-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H)-one

The title compound 6-amino-3-benzylmercapto-1,2,4-triazolo[3,4-f][1,2,4]-triazin-8(7H)-one (4), molecular formula C(11)H(10)N(6)OS, was obtained by the reaction of 3-amino-2-benzyl-6-hydrazino-1,2,4-triazin-5(2H)-one (3) with carbon disulfide in a water/pyridine mixture. Compound 4 can also be synthesized by reacting 6-amino-3(2H)mercapto-1,2,4-triazolo[3,4-f][1,2,4]triazin-8(7H)-one (7) with benzyl bromide in methanolic ammonia water. The compound crystallizes in the monoclinic space group P2(1)/c with a = 7.2926(15), b = 14.456(2), c = 11.436(2) A, beta = 105.30(2) degrees , V= 1162.9(4) A(3) and Z = 4, resulting in a density Dcalc of 1.567 g/cm(3). Molecules of 4 are linked by extensive intermolecular N-H...N and N-H...O hydrogen bonding [graph set R(2)(2 )(9)]. The structure is further stabilized by pi-pi stacking interactions.     

1,2,4-Triazines. 5. Regioselective N2-amination of 3-methylthio-1,2,4-triazin-5(2H)-ones. A new efficient synthesis of [1,2,4]triazolo[2,3-b][1,2,4]triazin-7(1H)-one

A regioselective synthesis of 2-amino-1,2,4-triazinones ( 3a-b ) is reported, by reaction of 3-methylthio-1,2,4-triazinones ( 1a-b ) with O-(2,4-dinitrophenyl)hydroxylamine ( 2 ), as an amino transfer agent. A spectroscopic study and an unequivocal synthesis of 2-amino-4-methyl-6-phenyl-1,2,4-triazinone ( 8a ) has shown the site of amination to be N2 of the 1,2,4,-triazinone ring. Subsequent reaction of 2-amino-1,2,4-triazinone ( 3b ) with ammonium hydroxide, followed by ring closure with formic acid provided [1,2,4]triazolo[2,3-b][1,2,4]triazin-7 (1H)-one ( 10 ).     

Amine-carbon disulfide promoted synthesis of novel benzo[e][1,3]thiazepin-5(1H)-one derivatives

In this paper, a simple method is introduced for the synthesis of novel 4-substituted-3-thioxo-3,4-dihydrobenzo[e][1,3]thiazepin-5(1H)-one derivatives. The synthesis is based on a two-step reaction of 2-methylbenzoic acid, an amine, and carbon disulfide. In the first step, 2-methylbenzoic acid reacts with sulfuric acid in ethanol, followed by the reaction with N-bromosuccinimide to produce ethyl 2-(bromomethyl)benzoate. Amine and carbon disulfide react in a separate flask in basic medium to give carbamodithioate salt. Carbamodithioate and ethyl 2-(bromomethyl)benzoate react together in dimethylformamide to produce the desired 4-substituted-3-thioxo-3,4-dihydrobenzo[e][1,3]thiazepin-5(1H)-one derivatives. The method is simple and fast and is applicable to a wide variety of substrates and gives the desired products in high isolated yields.     

吡唑并三嗪[1,5-a][1,3,5]-4(3H)-酮类衍生物的合成

设计并实现了以具有脒代吡唑结构的中间体与三聚光气在低温下进行分子内环合得到吡唑并三嗪[1,5-a][1,3,5]-4(3H)-酮衍生物(9a~9c)的新方法。1H NMR,IR,MS和元素分析表征证明9a~9c为新化合物。     

Synthesis of 8-R-7-amino-3-tert-butylpyrazolo- [5,1-c][1,2,4]triazin-4(6H)-ones derivatives

8-R-7-Amino-3-tert-butylpyrazolo[5,1-c][1,2,4]triazin-4(6H)-ones derivatives were isolated by boiling them with ketones, anhydrides, benzoyl chloride, and hydrazine. The structures of the compounds were established from data of elemental analysis, IR, ¹H NMR, and mass spectrometry.     

Synthesis of 8-Aryl[1,2,4]triazolo[1,5-d][1,2,4]triazin-5(6H)-ones by S HN Reactions

A new procedure has been proposed for the synthesis of 8-aryl[1,2,4]triazolo[1,5-d][1,2,4]-triazin-5(6H)-ones by reaction of 6-aryl-1,2,4-triazin-3(2H)-ones with hydrazides derived from aliphatic, aromatic, and heterocyclic carboxylic acids. The process invloves nucleophilic substitution of hydrogen (S_N ^H)in aryltriazinones, oxidative closure of azole ring, and Dimroth rearrangement.     

Synthesis and biological activity of 3,6-diaryl-7H-thiazolo[3,2-b][1,2,4]triazin-7-one derivatives as novel acetylcholinesterase inhibitors

Acetylcholinesterase inhibitors played significant roles in treatment of Alzheimer’s disease. Based on the research foundation of our previous work and molecular modeling, twelve 3,6-diaryl-7H-thiazolo[3,2-b][1,2,4]triazin-7-one derivatives were synthesized and characterized by mass spectra, infrared spectra, NMR and elemental analyses. The study of AChE inhibitory activity was carried out using the Ellman colorimetric assay with huperzine-A as the positive control. All target compounds exhibited more than 40% inhibition at 10 μM. Some target compounds showed good inhibition against AChE. The preliminary structure-activity relationships were the halogen atoms at the phenyl ring at the C6 position, the hydroxy groups and the long side chains at the phenyl ring at the C3 position of the parent nucleus played significant roles in the AChE inhibitory activity of the target compounds.     

Halo-heterocyclization of trans-5-phenyl-3-cinnamylsulfanyl[1,2,4]triazine into [1,3]thiazino[3,2-b][1,2,4]triazin-9-ium systems

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Synthesis and Characterization of [1,2,4,6]Thiatriazino[2,3-a][1,3]benzimidazol-1(2H)-one and [1,3,5]Thiadiazino[3,4-a][1,3]benzimidazol-2-imine

Abstract

The reaction of thionyl chloride with amidines 2, derived from N-benzimidazol-2-yl imidates 1, leads to [1,2,4,6]thiatriazino[2,3-a][1,3]benzimidazol-1(2H)-one 3 in good yields. [1,3,5]Thiadiazino[3,4-a][1,3]benzimidazol-2-imine 4 was prepared by condensation of NaSCN with benzimidazol-2-yl imidate 1. The isolated compounds 3 and 4 were identified by spectroscopic methods including IR, ¹H NMR, and ¹³C NMR as well as elemental analyses and MS of 3d and 4b.

GRAPHICAL ABSTRACT      

Facile synthesis of novel [1,3]oxazino[2,3-c][1,2,4] thiadiazin-12-one derivatives

Several novel fused heterocyclic systems which have rings containing N/O or N/S have been synthesized through a facile one-pot method by the treatment of substituted 2-(benzo[d]thiazol-2-yl)phenol and cyanogen bromide in THF and NEt₃. This one-pot method contains tough ring-opening of thiazole, special intermolecular rearrangement and ring-closing reactions. The newly synthesized compounds were characterized by HR-MS, ¹H-NMR, ¹³C-NMR spectral data and DFT calculation analysis. 2a was also determined by X-ray crystallographic analysis.     

Hydrolysis of 7,7-Substituted Derivatives of 3-tert-Butyl-3,4-dihydro-2H-thiazolo-[3,2-a][1,3,5]triazin-6(7H)-one

Alkaline hydrolysis of 3-tert-butyl-7,7-bis(hydroxymethyl)-3,4-dihydro-2H-thiazolo[3,2-a][1,3,5]-triazin-6(7H)-one can occur in three directions: with cleavage of the tetrahydrotriazine ring, with cleavage of the thiazolidine ring, and also with opening of both rings. Depending on the process conditions, either the hydrolysis product corresponding to the first direction or the hydrolytic decomposition products corresponding to the second and third directions can be obtained in preparative quantities. Hydrolysis of 3,3′-di-tert-butyl-3′,4′-dihydro-2′ H-spiro[(perhydro-1,3-oxazine)-5,7′-thiazolo[3,2-a][1,3,5]triazin]-6′-one in (NH₄)₂CO₃ solution occurs in two steps: in the first step, cleavage of the tetrahydrotriazine ring occurs; and in the second step, opening of the perhydrooxazine ring occurs. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1089–1097, July, 2005.     

A novel method for the synthesis of imidazo[5,1-f][1,2,4]triazin-4(3H)-ones

[reaction: see text] Imidazo[5,1-f][1,2,4]triazinones, as isosteres of purine, are of interest for pharmaceutical research. The syntheses reported in the literature generally require several steps. We report a novel method to access a broad range of diversely substituted derivatives. The key step is the electrophilic N-amination of 3H-imidazoles containing a 4-carbonyl group. Several different substituted imidazoles have been N-aminated in this manner. The resulting N-aminoimidazoles were cyclized under different conditions to the corresponding imidazotriazinones, which allowed for additional diversification. This novel method was applied in a formal synthesis of vardenafil, a well-known representative of this class of compounds. Furthermore, we report the first synthesis of a 7-aryl-imidazotriazinone via bromination of an unsubstituted imidazotriazinone followed by a Suzuki coupling.     

Synthesis of 3-tert-Butyl-7,8-nitro(dinitro)pyrazolo-[5,1-c][1,2,4]triazin-4(6H)-ones

Russian Journal of Organic Chemistry - 3-tert-Butyl-8-nitro-7-R-pyrazolo[5,1-c][1,2,4]triazin-4(6H)-ones (R = H, Cl, Br, NO2, N3) were prepared by nitration with HNO3/H2SO4 of the corresponding...