Amination of 5-Spiro-Substituted 3-Hydroxy-1,5-dihydro-2H-pyrrol-2-ones

The 3-hydroxy-1,5-dihydro-2H-pyrrol-2-one motif is a valuable scaffold in drug discovery. The replacement of the 3-oxy fragment in 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones-based compounds with a 3-amino one (3-amino analogs of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones, 3-amino-1,5-dihydro-2H-pyrrol-2-ones) can play a crucial role in their biological effect. Thus, approaches to 3-amino-1,5-dihydro-2H-pyrrol-2-ones are of significant interest. We developed an approach to 5-spiro-substituted 3-amino-1,5-dihydro-2H-pyrrol-2-ones that could not be obtained using previously reported approaches (reactions of 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones with amines). The developed approach is based on the thermal decomposition of 1,3-disubstituted urea derivatives of 5-spiro-substituted 3-hydroxy-1,5-dihydro-2H-pyrrol-2-ones, which were prepared via their reaction with carbodiimides.     

Reaction of 5-Aryl-4-hetaroyl-3-hydroxy-1-hydroxyethyl-1,5-dihydro-2H-pyrrol-2-ones with Nucleophilic Agents

Russian Journal of General Chemistry - The reaction of 5-aryl-4-hetaroyl-3-hydroxy-1-hydroxyethyl-1,5-dihydro-2H-pyrrol-2-ones with p-toluidine proceeds at the carbonyl group in the side chain at...     

Effective synthesis of 5-aryl-3-ethylidene-3H-pyrrol-2-ones

Substituted 5-aryl-3-ethylidene-3H-pyrrol-2-ones were synthesized by the reaction of the corresponding 4-aryl-4-oxobutanoic acids with ketones in the presence of aminating agents. The conditions of this reaction were developed with the use of both the conventional condensation technique and microwave activation. The structures of the reaction products were con-firmed by elemental analysis, IR spectroscopy, and ¹H NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 693–696, April, 2006.     

3-Phenylazo-4-methyl-2,3-dihydro-1,5-benzodiazepin-2-ones

The corresponding azo derivatives, which exist primarily in the azo form, are formed in the reaction of 2,3-dihydro-1,5-benzodiazepin-2-ones with diazonium cations. The hydrazone form of these compounds is possible in solutions of acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1558–1560, November, 1978.     

Parallel synthesis of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones

On the basis of the enaminone methodology, libraries of 3-amino-4H-quinolizin-4-ones, fused 3-amino-4H-pyrimidin-4-ones, and fused 3-amino-2H-pyran-2-ones were synthesized by the solid-phase and by the solution-phase parallel synthesis. The solution-phase approach turned out to be advantageous over the solid-phase approach. The solution-phase synthesis afforded, in most cases, analytically pure products in high yields, whereas the solid-phase approach gave products in poor yields and in low purity.     

Michael condensation of 3-arylidene-3H-pyrrol-2-ones and 3-arylidene-3H-furan-2-ones with cyclohexanone

The Michael condensation in the series of 5-aryl-3-arylidene-3H-pyrrol-2-ones and 5-aryl-3-arylidene-3H-furan-2-ones, containing an activated C=C bond, with cyclohexanone was investigated. It was shown that the condensation products were 1,5-dicarbonyl compounds containing a heterocyclic fragment. The enolization of one of the oxo groups, leading to the formation of hydroxypyrrole or hydroxyfuran structures, was demonstrated by the spectral data. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 823–827, June, 2007.     

Uncatalyzed solventless Diels-Alder reaction of 2-amino-3-nitroacrylate: synthesis of new epimeric 2-amino-3-nitro-norbornene- and norbornane-2-carboxylic acids

A highly diastereoselective Diels-Alder reaction between cyclopentadiene and ethyl (Z)-2-N-Boc-amino-3-nitroacrylate in neat conditions affords the ethyl 2-t-butoxycarbonylamino-3-endo-nitro-bicyclo[2.2.1]hept-5-ene-2-exo-carboxylate: a new constrained carbocyclic amino acid. Catalytic hydrogenation of this cycloadduct gave the corresponding reduced norbornane derivative. A preliminary investigation into the chemistry of these two amino acids was performed. In particular, the epimerization to their corresponding 3-exo-nitro compounds by treatment both with acid and base was studied. From this study, valuable information on the endo/exo process at the C-3 carbon atom, as well as on the stability of the different stereomers, was obtained. The stability is closely related to the presence or the absence of the double bond in the ring and to the substitution pattern. Finally, deprotection of the amino acid function has been performed.     

New synthesis of 1,3-dihydro-1,4-benzodiazepin-2(2H)-ones and 3-amino-1,3-dihydro-1,4-benzodiazepin-2(2H)-ones: Pd-catalyzed cross-coupling of imidoyl chlorides with organoboronic acids

A new approach to the synthesis of 1,4-benzodiazepines and 3-amino-1,4-benzodiazepines, which employs the Pd-catalyzed cross-coupling reaction of an imidoyl chloride with an organometallic reagent as the key step, is described. A five-step synthesis of a key intermediate is described and it is shown that in only four further steps (three couplings and a TFA-mediated BOC-deprotection) a wide variety of N1-, C3-amino-, C5-carbon-, or nitrogen-substituted 1,4-benzodiazepines can be synthesized.     

4-Amino-1,5-dihydro-2H-pyrrol-2-one aus Bortrifluorid-katalysierten Umsetzungen von 3-Amino-2H-azirinen mit Carbonsäure-Derivaten

4-Amino-1,5-dihydro-2H-pyrrol-2-ones from Boron Trifluoride Catalyzed Reactions of 3-Amino-2H-azirines with Carboxylic Acid Derivatives Reaction of 3-amino-2H-azirines 1 with ethyl 2-nitroacetate ( 6a ) in refluxing MeCN affords 4-amino-1,5-dihydro-2H-pyrrol-2-ones 7 and 3,6-diamino-2,5-dihydropyrazines 8 , the dimerization product of 1 (Scheme 2). Thus, 6a reacts with 1 as a CH-acidic compound by C? C bond formation via C-nucleophilic attack of deprotonated 6a onto the amidinium-C-atom of protonated 1 (Scheme 5). The scope of this reaction seems to be rather limited as 1 and 2-substituted 2-nitroacetates do not give any products besides the azirine dimer 8 (see Table 1). Sodium enolates of carboxylic esters and carboxamides 11 react with 1 under BF₃ catalysis to give 4-amino-1,5-dihydro-2H-pyrrol-2-ones 12 in 50–80% yield (Scheme 3, Table 2). In an analogous reaction, 3-amino-2H-pyrrole 13 is formed from 1c and the Li-enolate of acetophenone (Scheme 4). A reaction mechanism for the ring enlargement of 1 involving BF₃ catalysis is proposed in Scheme 6.     

Reactions of 4-acyl-1-alkoxyaryl-5-aryl-3-hydroxy-2,5-dihydro-1H-pyrrol-2-ones with nucleophilic reagents

4-Acetyl-1-alkoxyaryl-5-aryl-3-hydroxy-2,5-dihydro-1H-pyrrol-2-ones reacted with amines to give 1-alkoxyaryl-5-aryl-4-(1-R-aminoethylidene)pyrrolidine-2,3-diones. Reactions of amines with 4-benzoyl-substituted analogs involve nucleophilic attack on the C³ atom in the heteroring to produce the corresponding 3-R-amino-1-alkoxyaryl-5-aryl-4-benzoyl-2,5-dihydro-1H-pyrrol-2-ones. Reactions of the title compounds with hydrazine hydrate, regardless on the substituent on C₄, afforded 4-aryl-3-methyl(phenyl)-5-[2(4)-methoxyphenyl]-4,6-dihydropyrrolo[3,4-c]pyrazol-6-ones.     

Synthesis and anticonvulsant evaluation of 1-amino-1,3-dihydro-2H-benzimidazol-2-ones

1-Amino-2-benzimidazolinones containing alkyl substituents on the amino nitrogen have been prepared by the sodium bis (2-methoxyethoxy)aluminum hydride reduction of 1-acylamino-2-benzimidazolinones. The latter compounds were obtained in two steps from o-nitro-β-acylphenylhydrazines. All of the 1-amino-2-benzimidazolinones exhibited activity in the standard anticonvulsant tests except for the 1-benzylamino compound. The most active compound was 1-ethylamino-2-benzimidazolinone which protected mice in the maximal electroshock seizure test at 30 mg/kg.     

A new synthesis of 3-amino-1-aryl-2-pyrazolin-5-ones

Reaction of ethyl 3-nitropropionate with aryldiazonium chlorides in basic medium yields ethyl 3-nitro-3-(arylhydrazono)propionates. These α-nitrohydrazones are converted by catalytic hydrogenation to 3-amino-1-aryl-2-pyrazolin-5-ones, probably via cyclization of intermediate amidrazones produced in situ. This appears to be the first route to the title compounds that does not use a substituted phenyl hydrazine intermediate and offers advantages in the preparation of pyrazolinones bearing electron-rich aryl rings.     

Nitration of 8-substituted 2,3-dihydro-1H-1,5-benzodiazepin-2-ones

The nitration of a number of 8-R-4-R-2,3-dihydro-1H-1,5-benzodiazepin-2-ones with substituents in the diazepin (4-R=CH₃, C₆H₅, and C₆H₄OCH₃-p) and benzene (8-R=Cl, Br) rings takes place in the 7 position. The presence in the benzene ring of a strong electron-donor substituent (methoxy group), by determining the direction of electrophilic substitution in the ortho position with respect to it, leads to the formation of 7- and 9-nitro isomers in a ratio of 43.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 551–554, April, 1978.     

Synthesis of 4-styryl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones

4-Styryl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones were synthesized and their structure was established by means of PMR spectra and mass spectroscopy.Dnepropetrovsk State University Named in Honor of 300th Anniversary of the Reunion of Ukraina and Russia, Dnepropetrovsk 320625. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1560–1562, November, 1987.     

Solid-supported solution-phase synthesis of 4-amino-1,2,4,5-tetrahydro-2-benzazepine-3-ones

Starting from Boc-o-aminomethylphenylalanine, a solution-phase parallel synthesis of 2,4-substituted 4-amino-1,2,4,5-tetrahydro-2-benzazepine-3-ones is described. This heterocycle has two nitrogen functions, which are differentiated and can be selectively substituted. The sources of diversity are aldehydes for the R(1) position and carboxylic acids, sulfonyl chlorides, or isocyanates for the R(2) position. High-throughput synthesis and purification of this multistep synthetic sequence was accomplished using polymer-bound reagents and scavengers and liquid-liquid extraction protocols, and a small library of compounds was prepared. Polymer-bound cyanoborohydride was found to work well for the reductive amination. Scavenging of excess of amine was performed by polymer-bound benzaldehyde, and cyclization was performed in the presence of polymer-bound coupling reagent 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). After Boc-deprotection, the second nitrogen can be acylated using carboxylic acids, sulfonylated or converted to a urea. The acylation is again performed by polymer-bound EDC. Excellent yields and purities were obtained.     

Synthesis of 4-Pyridyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones

4-Pyridyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones were obtained by the condensation of ethyl nicotinoyl- or isonicotinoylacetates with o-phenylenediamine. Alkylation of the pyridylbenzodiazepinones with ethyl iodide under phase-transfer catalysis conditions occurred at the amide nitrogen of the heterocycle, whereas in nitromethane it occurred at the nitrogen of the pyridine substituent. Bromination with N-bromosuccinimide occurred at position 3 of the heterocycle. Pyridyldibenzodiazepinones underwent thermal rearrangement to derivatives of vinylbenzimidazole.     

Formylation of 4-aryl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones

The formylation of 8-chloro- and 8-methoxy-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones with the Vilsmeier reagent leads to 3-dimethylaminomethylene derivatives which, in the case of the 8-chloro derivative, have been converted by hydrolysis in acetic acid into 8-chloro-3-formyl-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-ones.Translated from Khimiya Geterotsiklicheskaya Soedinenii, No. 9, pp. 1262–1265, September, 1984.