Unusual transformations of lithium enolate of ethyl 4,4,4-trifluoro-3-oxobutanoate

The present paper describes unusual reactions of lithium enolate of ethyl 4,4,4-trifluoro-3-oxobutanoate with ammonium acetate and 1-aminonaphthalene. These reactions produce 4-amino-2,6-bis(trifluoromethyl)pyridine and 4-trifluoromethyl-2-[(Z)-1,1,1-trifluoroprop-1-en-2-ol-1-yl]benzo[h]quinoline, respectively. The reaction of 1,1,7,7,7-hexafluoroheptane-2,4,6-trione hydrate with 1-naphthylamine gives a mixture of 4-trifluoromethyl-2-[(Z)-1,1,1-trifluoroprop-1-en-2-ol-1-yl]benzo[h]quinoline and N,N??-bis(naphth-1-yl)-2,6-bis(trifluoromethyl)pyridine-4(1H)-imine, respectively.     

Über die Synthese von 5-(o-Chlorphenyl)-7-trifluormethyl-1Hthieno[3,2—e]-1,4-diazepin-2(3H)-on

The synthesis of 5-(o-chlorophenyl)-7-trifluoromethyl-1H-thieno[3.2?e]-1.4-diazepin-2(3H)-one (10) starting from ethyl 3-amino-5-trifluoromethyl-2-thiophenecarboxylate (1) is described.     

Trifluoromethyl-substituted 1,6-naphthyridines and pyrido[4,3-d]pyrimidines

A convenient method for the synthesis of 1-alkyl-5-trifluoromethyl-1,6-naphthyridin-4(1H)-ones was elaborated based on the reaction of 4-alkylamino-3-trifluoroacetimidoyl-3-penten-2-one diphenylboron chelates with dimethylformamide dimethyl acetal. 3-Acetyl-4-amino-2-trifluoromethylpyridine was used to obtain 5-trifluoromethyl-1,6-naphthyridin-4(1H)-one and its 2-methoxycarbonyl derivative, as well as 4-methyl-5-trifluoromethylpyrido-[4,3-d]pyrimidine.     

Reactions of regioisomeric 3,3-dimethyl- and 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyrones with N-nucleophiles

Reactions of 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyrone with ethylenediamine, hydrazine, or hydroxylamine yield 5-methyl-7-trifluoromethyl-2,3-dihydro-1H-1,4-diazepine, 3(5)-(2-hydroxy-2-methylpropyl)-5(3)-trifluoromethylpyrazole, and 5-hydroxy-3-(2-hydroxy-2-methylpropyl)-5-triflouromethyl-Δ², respectively. The same compounds were obtained from 2-amino-1,1,1-trifluoro-6-hydroxy-6-methylhept-2(Z)-en-4-one and 2-hydroxy-6, 6-dimethyl-2-trifluoromethyltetrahydro-4-pyrone.     

Stereocontrolled transformation of nitrohexofuranoses into cyclopentylamines via 2-oxabicyclo[2.2.1]heptanes. Part 6: synthesis and incorporation into peptides of the first reported 2,3-dihydroxycyclopentanecarboxylic acid

Herein we report the intramolecular alkylation of nitronates of methyl-5-O-benzyl-3,6-deoxy-6-nitro-β-d-glucofuranoside and methyl-5-O-benzyl-3,6-deoxy-6-nitro-α-d-glucofuranoside into the corresponding 2-oxabicyclo[2.2.1]heptane derivatives. Similarly, methyl-3-O-benzyl-5-deoxy-5-nitromethyl-β-d-xylofuranoside and methyl-3-O-benzyl-5-deoxy-5-nitromethyl-α-d-xylofuranoside were cyclized to (1R,3R,4S,5R,7R)-7-benzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptane and (1R,3S,4S,5R,7R)-7-benzyloxy-3-methoxy-5-nitro-2-oxabicyclo[2.2.1]heptane, respectively. These 2-oxabicyclo[2.2.1]heptane derivatives were eventually transformed into enantiopure methyl (1S,2S,3R,4S,5R)-2-amino-2,3-dihydroxycyclopentanecarboxylate and this novel β-amino acid was incorporated into peptides.     

Five-membered 2,3-dioxo heterocycles: LXIII. Cascade recyclization of isopropyl 2-(1-aryl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrol-3-yl)-2-oxoacetates with cyclic enamines. Crystalline and molecular structure of 1′-benzyl-6′,6′-dimethyl-3-[(Z)-phenyl(phenylamino)methylidene]-6′,7′-dihydro-3H-spiro[furan-2,3′-indole]-2′,4,4′,5(1′H,5′H)-tetraone

Isopropyl 2-(1-aryl-4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrol-3-yl)-2-oxoacetates reacted with N-substituted 3-amino-5,5-dimethylcyclohex-2-en-1-ones to give the corresponding 1′-substituted (Z)-6′,6′-dimethyl-3-[phenyl(arylamino)methylidene]-6′,7′-dihydro-3H-spiro[furan-2,3′-indole]-2′,4,4′,5(1′H,5′H)-tetraones. The structure of 1′-benzyl-6′,6′-dimethyl-3-[(Z)-phenyl(phenylamino)methylidene]-6′,7′-dihydro-3Hspiro[furan-2,3′-indole]-2′,4,4′,5(1′H,5′H)-tetraone was proved by X-ray analysis.     

4-Substituted 5-nitroisoquinolin-1-ones from intramolecular Pd-catalysed reaction of N-(2-alkenyl)-2-halo-3-nitrobenzamides

4-Methyl- and 4-benzyl-5-aminoisoquinolin-1-ones are close analogues of the water-soluble PARP-1 inhibitor 5-AIQ. Their synthesis was approached through Pd-catalysed cyclisations of N-(2-alkenyl)-2-iodo-3-nitrobenzamides. Reaction of N,N-diallyl-2-iodo-3-nitrobenzamide with Pd(PPh₃)₄ gave a mixture of 2-allyl-4-methyl-5-nitroisoquinolin-1-one and 2-allyl-4-methylene-5-nitro-3,4-dihydroisoquinolin-1-one. N-Benzhydryl-N-cinnamyl-2-iodo-3-nitrobenzamide similarly gave 2-benzhydryl-4-benzyl-5-nitroisoquinolin-1-one and 2-benzhydryl-4-benzylidene-5-nitro-3,4-dihydroisoquinolin-1-one. The isomeric products are not interconvertible. A deuterium-labelling study indicated that the isomers were formed by different pathways: a π-allyl-Pd route and the classical Heck route. The corresponding secondary amides N-allyl-2-iodo-3-nitrobenzamide and N-((substituted)-cinnamyl)-2-iodo-3-nitrobenzamide gave good yields of the required 4-methyl- and 4-((substituted)-benzyl)-5-nitroisoquinolin-1-ones, respectively, under optimised conditions (Pd(PPh₃)₄, Et₃N, Bu₄NCl, 150 °C, rapid heating). Hydrogenation of the nitro groups gave 4-methyl- and 4-benzyl-5-aminoisoquinolin-1-ones, which were potent inhibitors of PARP-1 activity.     

Synthesis of the dibenzo[f,h]phthalazine and dibenzo[f,h]cinnoline skeleton via a ‘Suzuki-Pd-catalyzed intramolecular arylation’ and a ‘Suzuki-Pschorr’ approach

Palladium-catalyzed intramolecular arylation of 2-benzyl-5-(2-bromophenyl)-4-phenylpyridazin-3(2H)-one yielded hitherto unknown 2-benzyldibenzo[f,h]phthalazin-1(2H)-one. The synthesis of this new tetracyclic pyridazinone from 2-benzyl-5-(2-aminophenyl)-4-phenylpyridazin-3(2H)-one via a Pschorr type reaction was also investigated. Similarly, the construction of 2-methyldibenzo[f,h]cinnolin-3(2H)-one from 2-methyl-5-(2-bromophenyl)-6-phenylpyridazin-3(2H)-one and 2-methyl-5-(2-aminophenyl)-6-phenylpyridazin-3(2H)-one is also reported. Removal of the N-benzyl protective group of 2-benzyl-dibenzo[f,h]phthalazin-1(2H)-one with AlCl₃ yielded unsubstituted dibenzo[f,h]phthalazin-1(2H)-one.     

Reactivity of 3H-1,2,4-dithiazole-3-thiones and 3H-1,2-dithiole-3-thiones as sulfurizing agents for oligonucleotide synthesis

The reactivity of 5-amino-3H-1,2,4-dithiazole-3-thiones substituted at their amino group and 5-amino-3H-1,2-dithiole-3-thiones substituted at their amino group and C4 toward compounds containing P(III) atoms has been studied. N,N-Disubstituted-N′-(3-thioxo-3H-1,2,4-dithiazol-5-yl)methanimidamides were selected as novel efficient sulfur transfer reagents suitable for DNA and RNA synthesis.     

Reaction of ketenes with N,N-disubstituted α-aminomethyleneketones VII. Synthesis of 2H,5H-[1]benzothiopyrano[4,3-b]pyran and 2H,5H-thiopyrano[4,3-b]pyran derivatives

The dipolar 1,4-cycloaddition of dichloroketerie to N,N-disubslituled 3-aminomethylene-2,3-dihydro-4-thiochromanones and 3-aminomethylenetelrahydro-4-thiopyranones gave N,N-disubstituted 4-amino-3,3-diehloro-3,4-dihydro-2H,5H-[1]benzolhiopyrano[4,3-b]pyran-2-ones and 4-amino-3,3-dichloro-3,4,7,8-tetrahydro-2H,5H-thiopyrano[4,3-b]pyran-2-ones, respectively, only in the ease of aromatic or strong hindering aliphatic N-substitution. The adducts gave N,N′-disubstituted 4-amino-3-chloro-2H,5H-[1]benzothiopyrano[4,3-b]pyran-2-ones and 4-amino-3-chloro-7,8-dihydro-2H,5H-thiopyrano[4,3-b]pyran-2-ones, respectively, by dehydro-chlorination with DBN. By chromatography on neutral alumina, 3-(2,2-dichloroethylidene)-2,3-dihydro-4-thiochromanone was isolated as an unstable liquid from the reaction between dichloroketerie and 3-diethylaminornethylene-2,3-dihydro-4-thiochromanone.     

Uranyl ion complexes with long chain aminoalcoholbis(phenolate) [O,N,O,O′] donor ligands

The reaction between uranyl nitrate hexahydrate and phenolic ligand precursor [(N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-4-amino-1-butanol) · HCl], H₃L1 · HCl, leads to a uranyl complex [UO₂(H₂L1)₂] (1a) and [UO₂(H₂L1)₂] · 2CH₃CN (1b). The ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-4-amino-1-butanol)H₃L2 · HCl], H₃L2 · HCl, yields a uranyl complex with a formula [UO₂(H₂L2)₂] · CH₃CN (2). The ligand [(N,N-bis(2-hydroxy-3,5-dimethylbenzyl)-5-amino-1-pentanol) · HCl], H₃L3 · HCl, produces a uranyl complex with a formula [UO₂(H₂L3)₂] · 2CH₃CN (3) and the ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-5-amino-1-pentanol) · HCl], H₃L4 · HCl, leads to a uranyl complex with a formula [UO₂(H₂L4)₂] · 2CH₃CN (4). The ligand [(N,N-bis(2-hydroxy-5-tert-butyl-3-methylbenzyl)-6-amino-1-hexanol) · HCl], H₃L5 · HCl, leads to a uranyl complex with a formula [UO₂(H₂L5)₂] · 4toluene (5). The complexes 1–5 are obtained using a molar ratio of 1:2 (U to L) in the presence of a base (triethylamine). The molecular structures of 1a, 1b, 3, 4 and 5 were verified by X-ray crystallography. All complexes are neutral zwitterions and have similar centrosymmetric, mononuclear, distorted octahedral uranyl structures with the four coordinating phenoxo ligands in an equatorial plane. In uranyl ion extraction studies from water to dichloromethane with ligands H₃L1 · HCl–H₃L5 · HCl, ligands H₃L1 · HCl, H₃L4 · HCl and H₃L5 · HCl are the most effective ones.     

Derivatives of α,β-dehydro amino acids: VI. Reaction of 4-benzylidene-2-phenyl-1,3-oxazol-5(4H)-one with piperidin-2-ylmethanamine

4-Benzylidene-2-phenyl-1,3-oxazol-5(4H)-one reacts with piperidin-2-ylmethanamine to give N-{(Z)-3-oxo-3-[(piperidin-2-ylmethyl)amino]-1-phenylprop-1-en-2-yl}benzamide, N-(4-benzyl-3-oxooctahydro-2N-pyrido[1,2-a]pyrazin-4-yl)benzamide, or/and (Z)-4-benzylidenehexahydro-2H-pyrido[1,2-a]pyrazin-3(2H)-one, depending on the solvent, temperature, and reaction time. The latter product is formed via three-step tandem process.     

Electrophilic cyclization of <Emphasis Type="Italic">N</Emphasis>-allyl(propargyl)-5-amino-1<Emphasis Type="Italic">H</Emphasis>-pyrazole-4-carboxamides. Synthesis of 4-[(dihydro)oxazol-2-yl]-1<Emphasis Type="Italic">H</Emphasis>-pyrazol-5-amines

N-Allyl-5-amino-1H-pyrazole-4-carboxamides in reactions with polyphosphoric acid, with N-halosuccinimides in chloroform, and with (chlorosulfanyl)benzenes in nitromethane in the presence of lithium perchlorate underwent cyclization involving the N-allylamide fragment to give 4-[5-methyl(halomethyl)-4,5-dihydrooxazol-2-yl]-1H-pyrazol-5-amines and 2-(5-amino-1H-pyrazol-4-yl)-5-[(arylsulfanyl)methyl]-4,5-dihydro-1,3-oxazolium perchlorates, respectively. Analogous reactions of N-propargyl-5-amino-1H-pyrazole-4-carboxamides with polyphosphoric acid afforded 4-(5-methyloxazol-2-yl)-1H-pyrazol-5-amines, and with (chlorosulfanyl) benzenes, 2-(5-amino-1H-pyrazol-4-yl)-5-[(arylsulfanyl)methylidene]-4,5-dihydro-1,3-oxazolium perchlorates.     

2-amino-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidines: Synthesis and reactions with electrophilic reagents

The hydrogenation of 2-amino-5-R-7-R′-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines with NaBH₄ led to the formation of 2-amino-5-R-7-R′-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidines. Acylation, sulfonylation, and alkylation of these compounds depending on conditions and the reagent character occur at the amino group, atoms N³ or N⁴. The treatment with alkali of 2-amino-3-benzyl-5-R-7-R′-4,5,6,7-tetrahydro-1,2,4-triazolo-[1,5-a]pyrimidinium bromide resulted in 2-amino-3-benzyl-5-R-7-R′-3,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]-pyrimidine, similar reaction of 2-acetamido-3-benzyl-5-R-7-R′-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]-pyrimidinium bromide gave a mesoionic product of a hydrogen elimination from the amide nitrogen atom.     

Synthesis of 1,3,4-thiadiazoles containing the trifluoromethyl group

The following compounds have been synthesized: 2-Amino-5-trifluoromethyl-1,3,4-thiadiazole; N-(5-trifluoromethyl - 1,3,4-thiadizol-2-yl)benzenesulfonamide; N¹-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)sulfanilamide, its N⁴-acetyl, N⁴-succinyl, and N⁴-pathalyl derivatives; o - m - and p-trifluoromethylbenzoylthiosemicarbazide, their corresponding 2-amino-1,3,4-thiadiazoles, their corresponding sulfanilamides, their N⁴-acetyl, N⁴-succinyl and N⁴-phthalyl derivatives; 3-o-trifluoromethylphenyl-4H-1,2,4-triazole-5-thiol. Preliminary in-vitro assays show that synthesized sulfanilamide derivatives have antibacterial activity against Staphylococcus aureus.     

Synthesis of 1,4,5-trisubstituted-1,2,3-triazoles via coupling reaction of diaminomaleonitrile with aromatic diazonium salts

A mild procedure for the preparation of 2-(5-amino-1-aryl-1H-1,2,3-triazol-4-yl)-2-iminoacetonitriles and 2-(5-amino-1-aryl-1H-1,2,3-triazol-4-yl)-2-oxoacetonitriles was achieved by the reaction of diaminomaleonitrile and phenyl/substituted phenyl diazonium chlorides. 4-Nitrophenyl diazonium chloride afforded 2-amino-3-(3-(4-nitrophenyl)triaz-1-en-1-yl)maleonitrile. Triazole iminoacetonitrile and maleonitrile derivatives were reacted further with excess acetone and benzaldehyde with a catalytic amount of 1,8-diazabicyclo[5.4.0]undec-7-ene to yield 5-(5-imino-2,2-dimethyl-2,5-dihydrooxazol-4-yl)-3-aryl-3H-1,2,3-triazol-4-amine and (E)-N-benzylidene-5-(5-imino-2-aryl-2,5-dihydrooxazol-4-yl)-3-aryl-3H-1,2,3-triazol-4-amine, respectively. Two competitive reactions, i.e., nucleophilic substitution and nucleophilic addition, were observed when triazole oxoacetonitrile and maleonitrile derivatives were reacted with hydroxylamine hydrochloride in the presence of sodium acetate.     

Synthesis of polyazaheterocycles containing linearly bound 1,2,4-thiadiazole using enaminones

A reaction of N-substituted 5-amino-3-(2-oxopropyl)-1,2,4-thiadiazoles with dimethylformamide dimethyl acetal gave 3-(5-amino-1,2,4-thiadiazol-3-yl)-4-(dimethylamino)but-3en-2-ones, whose cyclization with hydrazine, guanidine, 1H-pyrazol-5-amines and 6-aminopyrimidin-4(3H)-ones led to 3-methyl-1H-pyrazole, 4-methylpyrimidin-2-amine, 5-methyl3-arylpyrazolo[1,5-a]pyrimidines, and 5-methyl-2-R-pyrido[2,3-d]pyrimidin-4(3H)-ones containing a 5-amino-1,2,4-thiadiazole fragment linearly bound at position 3.     

Preparation of trifluoromethylated pyrazoles and 1,4-thiazine 1,1-dioxides from trifluoromethylated sulfone derivatives

Trifluoromethylated sulfones, 3-amino-2-arylsulfonyl-4,4,4-trifluoro-3-hydroxybutanenitrile ( 3 ) and 3-(aroylmethyl)sulfonyl-1,1,1-trifluoropropane-2,2,-diols 12 , were prepared and cyclized to 4-arylsulfonyl-5-trifluoromethyl-3-hydrazinopyrazoles 9 and 5-arylsulfonyl-3-trifluoromethyl-3-hydroxy-2,3-dihydro-4H-1,4-thiazine 1,1-dioxides 13 , respectively.     

Synthesis,characterization and biological activity of Hg(II), Fe(III) complexes with 1,3,4-oxadiazole, 1,2,4-triazole derivatives from L-methionine

Four novel heterocyclic1,3,4-oxadiazole, 1,2,4-triazole derivatives, namely: 5-[1-amino-3-(methylsulfanyl)propyl]-1,3,4-oxadiazole-2(3H)-thione (4), 4-amino-5-[1-amino-3-(methylsulfanyl)propyl]-4H-1,2,4-triazole-3-thiol (5), 1-amino-3-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-5-thiol (7), and 5-[1-amino-3-(methylsulfanyl)propyl]-1H-1,2,4-triazole-3-thiol (9) have been synthesized from l-methionine and characterized by different spectroscopic techniques (FT-IR, UV–Vis, ¹H NMR, ¹³C NMR and MS). Complex formation with Hg⁺⁺ and Fe⁺⁺⁺ ions were formed from the four heterocyclic 4, 5, 7 and 9. The antimicrobial activities for synthetic intermediates and final four products were assisted using paper disk diffusion method against Gram-negative bacteria: Escherichia coli, Pseudomonas aeroginosae and Gram-positive bacteria: Staphylococus aureus 25923, Staphylococus aureus 43300 and showed variant activity against some of the microorganisms tested.     

Five-membered 2,3-dioxoheterocycles: LXXIX. Three-component condensation of 1<Emphasis Type="Italic">H</Emphasis>-pyrrol-2,3-diones with acetonitriles and dimedone. Crystal and molecular structure of substituted spiro[chromene-4,3′-pyrrole]

5-Phenyl-4-ethoxycarbonyl-1H-pyrrole-2,3-diones react with acetonitriles and dimedone to form ethyl 2-amino-7,7-dimethyl-2′,5-dioxo-5′-phenyl-1′,2′,5,6,7,8-hexahydrospiro[chromene-4,3′-pyrrole]-4′-carboxylates. The crystal and molecular structure of ethyl 2-amino-1′-benzyl-7,7-dimethyl-2′,5-dioxo-5′-phenyl-3-cyano-1′,2′,5,6,7,8-hexahydrospiro[chromene-4,3′-pyrrole]-4′-carboxylate was proved by XRD analysis.