Selenium heterocycles XXV. Synthesis of thieno[3,4-d][1,2,3]-thiadiazole,selenolo[3,4-d][1,2,3]thiadiazole and pyrrolo[3,4-d][1,2,3]-thiadiazole. Three novel ring systems

Starting from the readily available 4-bromomethyl-5-benzoyl-1,2,3-thiadiazole and 5-bromomethyl-4-benzoyl-1,2,3-thiadiazole; thieno[3,4-d][1,2,3]thiadiazole, selenolo[3,4-d][1,2,3]-thiadiazole and pyrrolo[3,4-d][1,2,3]thiadiazole were synthesized in good yield.     

Chemistry of 1,2,3-thiadiazole. IV. Synthesis of [1]benzoxepino-[3,4-d][1,2,3]thiadiazole, [1]benzothiepino-[3,4-d][1,2,3]thiadiazole, [1]benzoxepino[4,3-d][1,2,3]thiadiazole, [1]benzoxepino[4,3-d]oxazole and [1]benzoxepino[4,3-d]oxazole. Four novel heterocycles

Starting from the readily available 4-bromomethy-5-carbethoxy 1,2,3-thiadiazole (V), 5-bromomethy-4-carbethoxy-1,2,3-thiadiazole (IX) and ethyl 2-aryl-5-bromomethyloxazole-4-carboxylate (XIV), 4,10-dihydro-10-oxo[1]benzoxepino[3,4-d][1,2,3]thiadiazole (Ia), 4,10-dihydro-10-oxo[1]benzothiepino[3,4-d][1,2,3]thiadiazole (Ib), 4,10-dihydro-4-oxo[1]benzothiepino[4,3-d] [1,2,3]thiazole (II), 2-aryl-4,10-dihydro-4-oxo[1]benzoxepino[4,3-d]oxazoles (XIXa-XIXc) and 2-aryl-4,10-dihydro-4-oxo[1]benzothiepino[4,3-d]oxazoles (XIXd-XIXf) were prepared.     

Synthesis and Ring Transformation of Pyrrolo[2,3-d][1,3]oxazine to Pyrrolo[2,3-d]Pyrimidines

A convenient route is reported for the synthesis of fused pyrrolo[2,3-d][1,3]oxazine and pyrrolo[2,3-d]-pyrimidine derivatives from 2-amino-1-benzyl-3-t-butoxycarbonyl]-4,5-dimethylpyrrole.     

Synthesis and Reactions of Some New Heterocyclic Compounds Related to Pyrrolylthieno[2,3-d]pyrimidines and Thieno[2,3-d][4,5-d]dipyrimidines

Abstract

Condensation of ethyl-5-amino-2,4-diphenylthieno[2,3-d]pyrimidine-6-carboxylate (3a) with 2,5-dimethoxy tetrahydrofurane in acetic acid gives the corresponding 5-pyrrolyl derivative4, which in turn could be easily reacted with hydrazine hydrate in ethanol yielding the carbohydrazide derivative5. Reaction of5 with aromatic aldehydes, acetylacetone, carbon disulfide or phenylisothiocyanate gave pyrrolyl derivatives6,7,8,9 respectively. On the other hand, condensation of 5-(1-pyrrolyl)-6-acetyl-2,4-diphenylthieno[2,3-d]pyrimidine11 with benzaldehyde afforded the corresponding chalcone12, which on treatment with hydrazine hydrate, phenyl hydrazine, or thiourea gave the pyrazolinyl derivatives13,14 and pyrimidinyl derivative15, respectively. Furthermore some new pyrimidothienopyrimidne16,17a–d,19,20a–c were obtained using 5-amino-carboxamide3c as starting material.     

A new heterocyclic structure. The [1,2,3]triazolo[1,5-d][1,2,4]triazine

The hydrazone derivatives of 4-benzoyl-1,2,3-triazole can easily be cyclised by reaction with various organic reagents (ortho esters, aldehyde and ketone compounds, phosgene, etc) which result in the incorporation of the introduced reagent's carbon atom into the new six membered ring. The newly created C-N bond of the resulting [1,2,3]triazolo[1,5-d][1,2,4]triazines displays a particular sensitivity due to the electron attracting effect of the triazole ring. Some mechanistic considerations are proposed to account for the observed results.     

Synthesis and unusual chemical reactivity of certain novel 4,5-disubstituted 7-benzylpyrrolo[2,3-d][1,2,3]triazines.

The fact that only two pyrrolo[2,3-d][1,2,3]triazines heterocycles had been reported in the literature prompted us to initiate studies designed to provide additional members of this ring system. Initial attempts to prepare additional derivatives of the 7-unsubstituted pyrrolo[2,3-d][1,2,3]triazin-4-ones were limited by their low chemical reactivity. Subsequently, 7-benzyl-5-carboxamidopyrrolo[2,3-d][1,2,3]triazin-4-one (16) was prepared from diethyl 2-nitropyrrole-3,4,-dicarboxylate via an alkylation, ammonolysis, reduction and intramolecular diazocoupling sequence. Conversion of 16 into 7-benzyl-4-(1,2,4-triazol-1-yl)pyrrolo[2,3-d][1,2,3]triazine-5-carbonitrile (17) was accomplished, and nucleophilic displacements of the 4-triazol-1-yl group were studied. Treatment of 17 with NH3/CH3CN gave a mixture of 4-amino-7-benzylpyrrolo[2,3-d][1,2,3]triazine-5-carbonitrile (19) and 2-amino-1-benzylpyrrole-3,4-dicarbonitrile (21). A mechanism to account for the formation of this mixture is described along with studies on the effect that ammonia concentration and a TFA catalyst have on the product ratio. Compound 19 was converted into the 5-carboxamide and 5-thioamide derivatives of 19.     

Synthesis and base-catalyzed cleavage of 1-aryl-4,9-dioxo-1H-naphtho[2,3-d][1,2,3]triazole 2-oxides

A method was developed for the synthesis of 1H-1-arylnaphtho[2,3-d][1,2,3]triazole-4,9-dione 2-oxides based on 2-arylamino-3-chloro-1,4-naphthoquinones. The reaction of 1H-1-arylnaphtho[2,3-d][1,2,3]triazole-4,9-dione 2-oxides with an ethanolic alkali solution affords 2-{[1-(aryl)-2-oxido-1H-1,2,3-triazol-4-yl]carbonyl}benzoic acids.     

Design and selection of pyrazolo[3,4-d][1,2,3]triazole-based high-energy materials

Structural Chemistry - In this study, we design a series of bridged energetic compounds based on pyrazolo[3,4-d][1,2,3]triazole to screen potential energetic materials with excellent detonation...     

Synthesis of thiopyrano[2,3-d] pyrimidines and thieno[2,3-d]pyrimidines

The reaction of 4-chloro-5-cyano-2-methylthiopyrimidine (I) with ethyl mercaptosuccinate (II) in refluxing ethanol containing sodium carbonate has afforded diethyl 3-amino-2-(methyl-thio)-7H-thiopyrano[2,3-d]pyrimidine-6,7-dicarboxylate (IV). Displacement of the methylthio group in IV with hydrazine gave the corresponding hydrazino derivative which underwent Schiff base formation with benzaldehyde or 2,6-dichlorobenzaldehyde. Treatment of IV in refluxing acetic anhydride afforded the corresponding diacetylated amino derivative. Partial saponification of IV with sodium hydroxide gave 5-amino-2-(methylthio)-7H-thiopyrano-[2,3-d]pyrimidine 6,7-dicarboxylic acid 6 ethyl ester (VIII). The reaction of 4-amino-6-chloro-5-cyano-2-phenylpyrirnidine (XI) with II resulted in the formation of ethyl 4-amino-6-(ethoxy-carbonyl)-5,6-dihydro-5-amino-2-phenylthieno[2,3-d]pyrimidine-6-acetate (XIII) which when subjected to hydrolysis gave ethyl 4,5-diamino-2-phenylthieno[2,3-d]pyrimidine-6-acetate isolated as the hydrochloride (XIV). Diazotization of IV with sodium nitrite in acetic acid unexpectedly afforded diethyl 5-(acetyloxy)-6,7-dihydro-6-hydroxy-2-(methylthio)-5H-thio-pyrano[2,3-d]pyrimidine-6,7-diearboxylate (XV). Several structural ambiguities were resolved by ir and pmr spectra.     

Pyrrolo[2,3-d] pyrimidines. I. 5-hydroxypyrrolo[2,3-d] pyrimidines

5-Hydroxy-7-alkyl-2-phenyl-7H-pyrrolo[2,3-d]pyrimidine-6-carbonitriles (VIIb-d) and 5-hydroxy-2-phenyl-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylic acid, ethyl ester (VIIa) were prepared from 5-carbethoxy-4-chloro-2-phenylpyrimidine (IV) via 4-[(cyanomethyl)alkylamino[-2-phenyl-5-pyrimidinecarboxylic acid, ethyl esters (Vb-d) and 4-[(carboxymethyl)amino]-2-phenyl-5-pyrimidinecarboxylic acid, diethyl ester (Va), respectively. The hydroxy group of the pyrrolo-[2,3-d]pyrimidines could be methylated, acetylated and tosylated. Hydrolysis of 5-methoxy-7-methyl-2-phenyl-7H-pyrrolo[2,3-d]pyrimidine-6-carbonitrile (IX) afforded the corresponding amide (X).     

Application of the aza-Wittig reaction for efficient synthesis of diversely substituted benzo[f]Chromeno[2,3-d]pyrimidine and benzo[f]chromeno[2,3-d][1,2,4]triazolopyrimidine derivatives

An efficient synthesis of novel benzo[f]Chromeno[2,3-d]pyrimidine and unknown benzo[f]chromeno[2,3-d][1,2,4]triazolopyrimidine derivatives is described utilizing ethyl-2-amino-4-phenyl-4H-benzo[f]chromene-3-carboxylate as precursor via aza-Wittig reaction. The process proved to be simple, high-yielding, and efficient.     

One-Pot Synthesis of Novel Spiro Pyrano[2,3-d][1,3]thiazolo[3,2-a]pyrimidine Derivatives

In a one-pot synthesis, 1′-methyl-2,3″-dioxo-5″-aryl-1,2,5a″,7″,8″,9a″-hexahydro-5″H,6″H-dispiro[indole-3,2′-pyrrolidine-3′,2″-pyrano[2,3-d][1,3]thiazolo[3,2-a]pyrimidine]-4′-carboxylic acid methyl ester was prepared via the sequential reaction of 4-aryl-octahydro-pyrano[2,3-d]pyrimidine-2-thione, dimethyl acetylenedicarboxylate (DMAD), and a mixture of isatin and sarcosine. All the novel spiro compounds, in moderate yields, were characterized thoroughly by infrared, NMR, mass spectromentry, and elemental analysis together with x-ray crystallographic analysis.     

Efficient Red Electroluminescence From Phenanthro[9,10-d]imidazole-Naphtho[2,3-c][1,2,5]thiadiazole Donor-Acceptor Derivatives

Red emission is one of the three primary colors and is indispensable for full color displays. Fluorescent materials that can generate efficient red electroluminescence (EL) are limited and need to be developed. In this work, we report efficient red emitters based on phenanthro[9,10-d]imidazole-naphtho[2,3-c][1,2,5]thiadiazole donor-acceptor derivatives. The molecules, abbreviated as PINzP and PINzPCN, exhibited high photoluminescence quantum yield (PLQY) up to unity in doped films. They can also reach a relatively high PLQY of ∼30% in neat films. PINzP and PINzPCN were capable of generating efficient red EL in doped devices with a maximum external quantum efficiency (EQE) of 6.96% and 5.92%, respectively.