4-Alkoxycarbonyl, 4-alkylthiocarbonyl and 5-alkoxycarbonyloxy derivatives of 1-substituted-3-methylpyrazol-5-ones

The reaction of 1-substituted-3-methylpyrazol-5-ones 1 with alkyl chloroformates and calcium hydroxide in dioxane have been studied. With 1-phenyl-3-methylpyrazol-5-one, the isolated product was alkyl 3-methyl-5-oxo-1-phenylpyrazole-4-carboxylate 2 but with 1-alkyl-3-methylpyrazol-5-one formation of 1-alkyl-5-alkoxycarbonyloxy-3-methylpyrazole 3 was observed. Replacement of alkyl chloroformate by bis(alkoxythiocarbonyl) sulfide results in the formation of 4-alkoxythiocarbonyl derivatives 4 in low yield with both 1-substituted-3-methylpyrazol-5-ones.     

Efficient synthesis of 5-substituted-4,5-dihydro-1,2,4-triazin-6-ones and 5-substituted-1,2,4-triazin-6-ones

Treatment of methyl α-(dimethylarninomethyleneamino)carboxylates 1 (from α-amino acids and dimethylformamide dimethylacetal) with hydrazine gives 5-substituted-4,5-dihydro-1,2,4-triazin-6-ones 2 , which are smoothly dehydrogenated to 5-substituted-1,2,4-triazin-6-ones 3 with potassium permanganate in acetone/acetic acid.     

Synthesis of 2-substituted-5-halo-2,3-dihydro-4(H)-pyrimidin-4-ones and their derivatization utilizing the Sonogashira coupling reaction in the enantioselective synthesis of alpha-substituted beta-amino acids

A convenient, one-pot procedure for the synthesis of 1-benzoyl-2(S)-substituted-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones by tandem decarboxylation/beta-iodination of the corresponding 6-carboxy-perhydropyrimidin-4-ones was developed. In addition, several 1-benzoyl-2(S)-substituted-5-bromo-2,3-dihydro-4(H)-pyrimidin-4-ones were readily prepared by bromination of 1-benzoyl-2(S)-substituted-2,3-dihydro-4(H)-pyrimidin-4-ones. Subsequently, Sonogashira coupling of the halogenated heterocyclic enones with various terminal alkynes produced 1-benzoyl-2(S)-isopropyl-5-alkynyl-2,3-dihydro-4(H)-pyrimidin-4-ones in good yields. Hydrogenation of the unsaturated C-C moieties in the Sonogashira products followed by acid hydrolysis afforded highly enantioenriched alpha-substituted beta-amino acids.     

Synthesis of 1- and 4-substituted-5H-benzo[a]phenoxazin-5-ones

The 1- and 4-substituted-5H-benzo[a]phenoxazin-5-ones (substitutents: nitro, amino and acetylamino) were prepared by the condensation of o-aminophenol with 5-substituted-2,3-dichloro-1,4-naphthoquinones. The resulting compounds were subjected to reduction, acetylation and dehalogenation.     

Transformation of methyl N-methyl-N-(6-substituted-5-nitro-4-pyrimidinyl)aminoacetates into 4-methylamino-5-nitrosopyrimidines and 9-methylpurin-8-ones

N-Methyl-N-(6-substituted-5-nitro-4-pyrimidinyl)aminoacetic acid methyl esters under the treatment of sodium alkoxides, depending on the nature of substituents in 6 position of the pyrimidine ring, undergo ring closure and rearrangement to give 6-substituted-4-methylamino-5-nitrosopyrimidines or 9-methylpurin-8-ones.     

Diastereoselective synthesis of alpha-methyl and alpha-hydroxy-beta-amino acids via 4-substituted-1,3-oxazinan-6-ones

1,3-oxazinan-6-ones have been utilized in a series of enolate reactions to produce 5-hydroxy and 5-alkyl-4-substituted-1,3-oxazinan-6-ones with excellent trans diastereoselectivity. Highlighting the versatility of the oxazinanone, a number of transformations were performed to produce a variety of protected N-H and N-methyl alpha-hydroxy- and alpha-methyl-beta-amino acids.     

Eco-friendly rapid synthesis of 3-substituted-2-thioxo-2,3-dihydroquinazolin-4(1H)-ones in choline chloride based deep eutectic solvent

A series of 3-substituted-2-thioxo-2,3-dihydroquinazolin-4(1H)-ones and 6-iodo-3-substituted-2-thioxo-2,3-dihydroquinazolin-4(1H)-ones were synthesized in choline chloride/urea deep eutectic solvent. Substituted 2-mercapto-4(3H)-quinazolinones were synthesized from anthranilic acid or 5-iodoanthranilic acid and appropriate isothiocyanates in good to excellent yields. Isolation of final product was easy and required no further purification. Synthesis of these compounds was rapid, selective, and catalyst free, while preparation of deep eutectic solvent was easy, components are readily available, cheap, and environmentally friendly.     

3-取代-(1H)-嘧啶[1, 2-a]喹啉-1-酮和2-取代嘧啶[1, 2a]苯骈 咪唑-4-(10H)- 酮的简便合成法

本文利用2-氨基喹啉和2-氨基苯骈咪唑作为亲核试剂,与5-(双甲硫基亚甲基)丙二酸亚异丙酯(1)、5-(甲硫基亚烃基)丙二酸亚异丙酯(3)反应,开发出3-取代-(1H)-嘧啶-[1,2-a]喹啉-1-酮(5)和2-取代嘧啶[1,2-a]苯骈咪唑-4-(10H)-酮(6)通用的简便合成法。     

Reaction of ethyl γ-bromo-β-methoxycrotonate with carbonyl compounds. Synthesis of 4-methoxy-6-substituted-5,6-dihydro-2H-pyran-2-ones and 3-substituted 3-pyrazolin-5-ones

Ethyl β-methoxycrotonate I reacts with substituted carbonyl compounds II in benzene to give 4-methoxy-6-substituted-5,6-dihydro-2H-pyran-2-ones III. The reaction of IIIa and j with hydrazine hydrate in ethanol leads to 3-[(1′-thienyl-1-hydroxy)methyl]-5-hydroxy-1H-pyrazole (IVa) and 3-[1′-styryl-1′-hydroxy)methyl]-5-hydroxy-1H-pyrazole (IVj) in good yields. The structure of the products were assigned and confirmed on the basis of their elemental analysis and the electronic absorption, infrared and nmr spectra.     

Synthesis of 4-alkyl-, 4-aryl- and 4-arylamino-5-aminoisoquinolin-1-ones and identification of a new PARP-2 selective inhibitor

The considerable interest in substituted isoquinolin-1-ones related to 5-aminoisoquinolin-1-one (5-AIQ) as drugs points to a need for an efficient and straightforward synthesis of the 4,5-disubstituted bicycles. Bromination of 5-nitroisoquinolin-1-one gave 4-bromo-5-nitroisoquinolin-1-one but neither this nor 5-amino-4-bromoisoquinolin-1-one would participate in Pd-catalysed couplings. Protection of the lactam as 1-methoxy- and 1-benzyloxy-4-bromo-5-nitroisoquinolines, however, permitted Stille, Suzuki and Buchwald-Hartwig couplings to take place in high yields, insensitive to electronic demands and severe steric bulk in the arylboronic acids. Lithiation of 4-bromo-1-methoxy-5-nitroisoquinoline and quench with iodomethane gave 1-methoxy-4-methyl-5-nitroisoquinoline in low yield. Demethylation of the 1-methoxy-4-substituted-5-nitroisoquinolines with hydrogen bromide gave 4-substituted-5-nitroisoquinolin-1-ones, whereas hydrogenolytic debenzylation was achieved with simultaneous reduction of the 5-nitro group. 5-Amino-4-(4-trifluoromethylphenyl)isoquinolin-1-one was identified as a new potent and selective inhibitor of poly(ADP-ribose)polymerase-2 (PARP-2).     

5-乙氧羰基-4-取代-6-甲基-3,4-二氢嘧啶-2(1H)-酮的电子轰击飞行时间质谱表征

The electron ionization time-of-flight (TOF) mass spectra of a series of 5-ethoxycarbonyl-4-substituted-6-methyl-3,4-dihydropyrimidin-2(1H)-ones were studied to establish their fragmentation processes. Using the high resolution capabilities of the TOF instrument, exact masses for each fragment were determined. These data were used to infer molecular formulas and elemental compositions for all molecular ions and fragments through software interpretation and according to the established fragmentation rules the majority of ions were fully assigned. Two main fragmentation routes can be found in this work. First of them, for all the title compounds, includes the formation of three cations, by loss of R1 from the position 4, C2H4 (via a McLafferty rearrangement) from the ester group and H2O via a cyclic-six-membered transition state. The second route, for 4-aromatic compounds, consists of the formation of a cation by loss of EtCO2. Several additional fragmentations for individual compounds are proposed.     

Synthesis of 3-substituted-3,4-dihydro-2H-1,3-benzothiazin- 2-ones via a highly regioselective palladium-catalyzed carbonylation of 2-substituted-2,3-dihydro-1,2-benzisothiazoles

A novel synthesis of 3-substituted-3,4-dihydro-2H-1,3-benzothiazin-2-ones is described herein. The strategy relies on a highly regioselective palladium-catalyzed carbonylation of 2-substituted-2,3-dihydro-1,2-benzisothiazoles to give the corresponding 3,4-dihydro-2H-1,3-benzothiazin-2-one derivatives in good to excellent yields.     

室温下三光气作环合剂合成5-取代-1,3,4-噁二唑-2-酮类化合物

1,3,4-噁二唑具有抗菌,抗肿瘤,抗惊厥等生物活性~([1-6]),在药物化学方面具有重要的理论意义和实际应用价值.1,3,4-噁二唑类材料具有优良的荧光性和闪烁性和优异的电子传输性能,以及特殊的稳定性和良好的耐热性,被认为是下一代显示器件中载流子输送的首选材料~([7-8]).     

Ready access to enantiopure 5-substituted-3-pyrrolin-2-ones from N-benzyl-2,3-O-isopropylidene-d-glyceraldehyde nitrone (BIGN)

The reaction of the lithiated salt of methyl propiolate with N-benzyl-2,3-O-isopropylidene-d-glyceraldehyde nitrone (BIGN) afforded the corresponding propargyl hydroxylamines in a stereocontrolled way depending on the nature of the Lewis acid used as an additive. Subsequent reduction of the obtained hydroxylamines provided chiral 5-substituted-3-pyrrolin-2-ones, in high overall yields.     

Synthesis of 4-substituted-3-aminopiperidin-2-ones: application to the synthesis of a conformationally constrained tetrapeptide N-acetyl-Ser-Asp-Lys-Pro

A new and practical synthetic strategy is developed for the synthesis of six-membered lactam-bridged dipeptides, 4-substituted-3-aminopiperidin-2-ones, featuring two key steps: (a) a diastereoselective addition of cuprate to (E)-alpha,beta-unsaturated ester (3) and (b) racemization-free reductive amination. On the basis of this methodology, conformationally constrained tetrapeptide N-acetyl-Ser-Asp-Lys-Pro (AcSDKP) (2) has been successfully synthesized from 3-amino-4-vinylpiperidin-2-one (22).     

Formation of 2-halomethylene-4-cyclopentene-1,3-diones and/or 2-halo-1,4-benzoquinones via ring-expansion of 4-ethynyl-4-hydroxy-2,3-substituted-2-cyclobuten-1-ones. Total synthesis of methyl linderone

An in-depth study of the reactions of 4-(ethynyl)-4-hydroxy-2,3-substituted-2-cyclobuten-1-ones with N-bromo- or N-iodosuccinimide, affording in most cases 2-halomethylene-4-cyclopentene-1,3-dione, is described. This reaction was used in a short total synthesis of methyl linderone.     

Saturated heterocycles. 57. Synthesis of 4-substituted-9,10-dialkoxy-1,6,7,11b-tetrahydro-2H-pyrimido[6,1-a]isoquinolin-2-ones

A large number of 4-substituted-9,10-dialkoxy-1,6,7,11b-tetrahydropyrimido[6,1-a]isoquinolin-2-ones were prepared by the reaction of 1-(ethoxycarbonylmethyl)-6,7-dialkoxy-1,2,3,4-tetrahydroisoquinolines with iminoethers. Reaction of the corresponding isoquinoline-1-acetic acid derivatives with iminoethers led to the formation of N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides. In the hydrolysis of the prepared 4-substituted-pyrimido[6,1-a]isoquinolin-2-ones, the corresponding N-acyl-1,2,3,4-tetrahydroisoquinolin-1-acetamides were obtained. While reduction of the 4-phenyl derivative resulted in the corresponding 1,3,4,6,7,11b-hexahydropyrimidinone. The steric structures of the tetrahydro- and hexahydropyrimido[6,1-a]isoquinolines were determined by nmr spectroscopy.     

Synthesis and Suzuki-Miyaura reactions of 5-halo-3,4-dihydropyrimidin-2(1H)-ones

A novel synthesis of 6-methyl-4-phenyl-5-substituted-3,4-dihydropyrimidin-2(1H)-ones from 6-methyl-4-phenyl-5-halo-3,4-dihydropyrimidin-2(1H)-ones via the Suzuki-Miyaura reaction is reported. These previously unknown heterocyclic halides are easily prepared using the Biginelli multicomponent reaction followed by halodecarboxylation. The effect of varied substitution at the C-4 position on the cross-coupling reaction is also examined.     

Syntheses of optically active tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones and hexahydroimidazo[1,2-a]pyridin-2(3H)-ones

The reactions of (2S)-2-amino-2-substituted-N-(4-nitrophenyl)acetamides 16a-c, succindialdehyde (13), and benzotriazole afforded enantiopure (3S,5R,7aR)-5-(1H-1,2,3-benzotriazol-1-yl)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 17a-c, which were converted by sodium borohydride into (3S,7aR)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 18a-c. Chiral (2S)-2-amino-2-substituted-N-(4-methylphenyl)acetamides 12a-d, easily prepared in two steps from N-Boc-alpha-amino acids 10a-d, similarly reacted with glutaraldehyde (20) and benzotriazole to generate 5-benzotriazolyl-3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 21a-d, which were converted by sodium borohydride directly into optically active 3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 22a-d.     

A novel route to dipeptide and its derivative by means of the palladium catalyzed facile cleavage of 1-(1-methoxycarbonyl)alkyl-3-substituted-4-arylazetidin-2-ones

1-(1-Methoxycarbonyl)alkyl-3-substituted-4-arylazetidin-2-ones were found to be cleaved exclusively at the NC⁴ bond by the hydrogenolysis on palladium catalyst to give the corresponding dipeptide and its derivative in excellent yields.