Optimization of the synthesis of het/aryl-amidoximes using an efficient green chemistry

Abstract

This work focuses on optimizing an efficient green synthesis of arylamidoximes from appropriate nitrile and hydroxylamine hydrochloride in water and triethylamine (1.6?mol equivalent) as a base at room temperature for 6?h. This new green synthetic methodology is compared with previously known methods. The main advantages of this new process reported are good yield, easier work-up and short reaction times. Moreover, some of the synthesized arylamidoximes converted to 1,2,4-oxadiazole derivatives 13a,b and 14 via the reaction with (4-acetylphenoxy)acetic acid 12.     

一种新的合成12-氧代-1,15-十五内酰胺的方法

设计了一种新的合成12-氧代-1,15-十五内酰胺(4)的方法, 即以α-硝基环十二酮(1)为原料, 经与丙烯腈的Michael加成, 氰基选择性还原为氨基后扩环, 再经Nef反应合成了4, 总收率为28%.     

Design,synthesis, and toward a side-ring optimization of tricyclic thieno[2,3-d]pyrimidin-4(3H)-ones and their effect on melanin synthesis in murine B16 cells

Abstract

Herein, we report the synthesis of 48 novel 3-sulfonylamides containing a tricyclic thieno[2,3-d]pyrimidin-4(3H)-one moiety, and their influence on melanin synthesis in murine B16 cells. All target sulfonylamides were synthesized through key intermediate 3-nitro-thieno[2,3-d]pyrimidin-4(3H)-ones using three types of ipso-nitration reactions. In this case, we converted the pyrido[1,2-a]- fragment of the thieno[2,3-d]pyrimidine moiety to pyrrolo[1,2-a]- and azepino[1,2-a]- side-rings in order to evaluate the bioactivities of the synthesized derivatives for a structure activity-relationships point of view. The obtained results suggest that some of the selected compounds revealed a promising influence on melanin synthesis in murine B16 cells and may serve as lead compounds for further drug discovery and development.     

METHYLTHIODITHIOLYLIUM REACTIONS WITH 2-BUTENE NITRILES DERIVATIVES

Abstract

The 3-methylthio-1. 2-dithiolylium including at 5 position a donor substituent, in acetic acid in the presence of pyridine, the 2-methylthio-1. 3-dithiolylium ions in methylene chloride-triethylamine, react with the 2-butene nitrile derivatives and lead to the (A) and (B) corresponding 4-dithiolylidene-2-butene nitriles. In contrast ring opening reaction of the 1, 2-dithiole is observed when 2-cyano-3-phenyl-2-butene nitrile reacts with the 3-methylthio-4-aryl-1. 2-dithiolylium ions in 3 and 5 positions, in methylene chloride-triethylamine. The nucleophilic attack on the 5 position of the dithiolylium ion leads to a 2-cyano-3-phenyl-3 (4-aryl-5-methylthio-2-thienyl) propene nitrile (C), meanwhile the attack on the 3 position leads to a 2-cyano-3-phenyl-3-(4-aryl-3-mercapto-2-thienyl) propene nitrile (D). The proposed structures are established by means of physical methods (IR, NMR, and Mass Spectrometry) and by non ambiguous synthesis. The reactivities of the various sites are explained in function of the electronic and steric effects, furthermore the reaction conditions and the intermediary isolation allow to propose the mecanisms of these reactions.     

Nitrile Containing Bisphosphonates: Easy Synthesis through Metal Catalyzed Michael Addition

New nitrile‐containing gem‐bisphosphonates as drug candidates for the contrast of osteoporosis are presented, their synthesis being based on the metal catalyzed Michael conjugate addition of trimethylsilyl cyanide to unsaturated bisphosphonate precursors. Zn(OT f)₂ turned out to be the most efficient metal catalyst for the reaction enabling the formation of β‐nitrile substituted bisphosphonates in good yields. The corresponding final bisphosphonic acids bearing the nitrile moiety were obtained by deprotection of the ethyl ester moiety. They showed aggregation properties in water due to their amphiphilic nature and will be evaluated in order to assess their biological anti‐osteoclast activity.     

New methods of preparation of nitrile oxides and the corresponding disubstituted furoxans by interaction of N2O4 with salts of substituted dinitromethanes

A new method of generation of nitrile oxides through interaction of N₂O₄ with salts of substituted dinitromethanes (1) has been worked out. It has been shown by¹H,¹³C,¹⁴N NMR spectroscopy that this reaction proceeds via dinitronitrosomethyl intermediates (one of these has been isolated), and that the reaction is feasible only for substituents capable of conjugation with the nitrile oxide fragment. On the basis of cyclodimerization of the obtained nitrile oxides, preparative methods of synthesis of symmetrically substituted furoxans have been developed.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 147–151, January, 1993.     

Novel Synthesis of 1-(1,2,3,5,6,7-Hexahydro- s-indacen-4-yl)-3-[4-(1-hydroxy-1-methyl-ethyl)-furan-2-sulfonyl]urea,an Anti-inflammatory Agent

Abstract

A novel synthesis of the anti-inflammatory agent 1-(1,2,3,5,6,7- hexahydro-s-indacen-4-yl)-3-[4-(1-hydroxy-1-methyl-ethyl)-furan-2-sulfonyl] urea 1 is described. Sulfonamide 5 was prepared starting from ethyl 3-furoate 2. Key steps were a one-pot sulfonylation with chlorosulfonic acid in methylene chloride followed by pyridinium salt formation and reaction with phosphorus pentachloride to provide ethyl 2-(chlorosulfonyl)-4-furoate 7. This sulfonyl chloride was treated with ammonium bicarbonate to form sulfonamide 8, followed by treatment with excess methyl magnesium chloride to provide 4-(1-hydroxy-1-methyl-ethyl)-furan-2-sulfonamide 5. 4-Isocyanato-1,2,3,5,6,7-hexahydro-s-indacene 16 was prepared from indan in five steps. The formation of the desired sulfonyl urea was carried out both with the isolated isocyanate 16 and via an in situ method.     

Eco-friendly synthesis of 2-azetidinone analogs of isonicotinic acid hydrazide

Abstract

2-Azetidinones possess broad and potent activity due to presence of β-lactam ring and has been established as one of the biologically important scaffolds. The synthesis of N-(4-aryl-2-oxoazetidinone)-isonicotinamide by novel methods of stirring and sonication are described. The conventional method for synthesis of 2-azetidinones involves use of Dean–Stark water separator for the removal of water from the reaction with long reaction time (12–16 h reflux) at a very low temperature (?70 to ?90°C). The microwave method reported requires inert atmosphere of nitrogen gas for the synthesis of 2-azetidinones. We report herein the synthesis of 2-azetidinone analogs of isonicotinic acid hydrazide by novel green route methods of sonication and stirring using molecular sieves. Results indicate that higher yields and shorter reaction times can be achieved by employing novel green route methods of synthesis.     

A new strategy for isoflavone C-glycoside synthesis: The total synthesis of puerarin

Abstract

Given that C-glucosylisoflavones often possess promising biological activities, the development of an efficient synthetic method for this type of molecules is useful for drug discovery. Accordingly, a highly efficient five-step strategy was developed for the total synthesis of puerarin, an isoflavone C-glycoside. An alkyl substituent 4-CH₃OC₆H₄CH₂CH₂ with an electron-donating group on the aromatic ring was used to enhance the reactivity of phenol and the regioselectivity of O-C rearrangement of phenol glycoside. Thus, coupling of the ethylbenzene derivative of a phenol 1c with glycosyl trifluoroacetimidate 2 resulted in C-glycoside 3c in a 46.2% yield, which was easily de-tert-butylated with trifluoroacetic acid and oxidized with 2,3-dicyano-5,6-dichlorobenzoquinone to produce deoxybenzoin 5. The ring closure reaction of 5 followed by deprotection gave puerarin. This new synthetic strategy is also suitable for the total synthesis of other C-glucosylisoflavones.     

CATALYSE INTRAMOLECULAIRE DE L'AMINOLYSE DES HETEROCYCLES PHOSPHORES DERIVES DES α AMINOAMIDES. II: ETUDE DE LA CYCLISATION DES PHOSPHORDIAMIDES INCORPORANT UN RESIDU DE β AMINOACIDE,REACTIVITE VIS A VIS DE NUCLEOPHILES DES HETEROCYCLES FORMES

Abstract

Derivatives of β aminoacids in form of esters 1 or nitrile 4 (table I) undergo in an alcohol-ate/alcohol medium a rearrangement (Fig. 2), with formation of a β peptide link, resulting in the formation of esters 6 (table II). According to the experimental conditions the six membered ring heterocycles 5 are detected or isolated. They are also synthetized by cyclisation of acids 2 or hydrazide 3 (Fig. 5). While phosphorus easily reacts with alcohols and water, leading respectively to esters 6 and acids 9 (Fig. 7), it remains unaffected by amines. These results are discussed in term of mechanisms of the phosphorylation. The applications for β peptide synthesis and the participation of the p amide group in phosphorylation are limited.     

SYNTHESIS OF 2-THIOXOPYRIDO[2,3-d]PY RIMIDINE-4- ONES AND 1,4-BRIDGED BIS-2-THIOXO-1,2,3,4-TETRAHYDRO-5-PYRIMIDINE CARBOXYLIC ACID ETHYL ESTER DERIVATIVES

Abstract

The synthesis and structural characterization of 2-thioxopyrido[2,3-d]pynmidinethiones 5,9,12 and 4,4′-(1,4-phenylene)-di-(2-thioxo-1,2,3,4-tetrahydropyrimidines) 16-22 are described.     

Synthesis of 3-Substituted Pyrazole Derivatives by Mixed Anhydride Method and Study of Their Antibacterial Activities

A convenient synthesis of 3-substituted pyrazole derivatives by a mixed anhydride method using i-butylchloroformate and N-methylmorpholine at ?20 °C in tetrahydrofuran and study of in vitro antibacterial activities of the prepared compounds against Staphylococcus epidermidis, Bacillus subtilis, Pseudomonas aeruginosa, and Proteus valguris by agar-diffusion method were carried out. The results suggested that the products 4a, 4b, and 4c exhibited moderate to feeble inhibition against all test bacteria at greater concentration but 4d was best against Staphylococcus epidermidis (22 mm) and worst against Pseudomonas aeruginosa (16 mm) at the greatest concentration (2.5 mg/ml), and the activities decreased with decrease in concentration.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Synthesis and anticancer activity of some novel diethyl {(chromonyl/pyrazolyl) [(4-oxo-2-phenyl-quinazolin-3(4H)-yl)amino]methyl}phosphonates

Abstract

The synthesis of some novel chromonyl and pyrazolyl α-aminophosphonates containing a quinazolinone ring was carried out by applying Pudovik and Kabachnik-Fields reactions under solvent- and catalyst-free conditions. The anticancer activities of these compounds were evaluated against five cancer cell lines. 3-{[(3-Phenyl/1,3-diphenyl-1H-pyrazol-4-yl)methylidene]amino}-2-phenyl-quinazolin-4(3H)-ones (3d,e) and diethyl {[3-phenyl/1,3-diphenyl-1H-pyrazol-4-yl][(4-oxo-2-phenyl-quinazolin-3(4H) yl)amino] methyl}phosphonates (4d,e) displayed the potent anticancer activities against HCT116, MCF-7 and HepG2 cell lines in comparison with the standard drug.     

Stereoselective total synthesis of C2-symmetric natural products pyrenophorol and its derivatives

Abstract

A stereoselective total synthesis of 16-membered C₂-symmetric macrodiolide Pyrenophorol, Tetrahydropyrenophorol and 4,4-diacetylpyrenophorol have been accomplished. The synthesis started from commercially available L-Aspartic acid and the key reactions involved are regioselective epoxide opening, CBS reduction, Pinnick oxidation and Mitsunobu dilactonization.     

Synthesis of Novel Spiro Tetrahydrothiapyrano-Isoxazolines and Pyrazolines

Cis 2,6-Diphenyltetrahydrothiapyranone (1) was subjected to Wittig reaction to generate exocyclic double bond (2a-c). Cycloaddition of nitrile oxides and nitrile imines to the latter led to a novel spiro tetrahydrothiapyranoisoxazolines (3a-f) and spiro tetrahydrothiapyranopyrazolines (4a-f)     

Formal Synthesis of Ambrox® and 9-Epiambrox

(-)-Drimenol (5) was used as starting material for the synthesis of diastereoisomeric diols 3 and 4, through the nitrile 7, Compounds 3 and 4 are the direct precursors of Ambrox® (1) and 9-epiambrox (2).     

Theoretical Aspects of Cycloaddition Reactions of Phosphorylnitrile Oxides to Unsaturated Compounds

Abstract

Ab initio (4–31G?) and semiempirical (MNDO, AMI) quantum-chemical calculations of phosphorus-functionalized and non- phosphorylated nitrile oxides have been done. In approximation of general multielectronic perturbation theory, all nitrile oxides, including trifluoroacetonitrile oxide and dialkoxyphosphorylnitrile oxides, by type of orbital interactions qualify as electron-donor dipoles.     

Diastereoselective Synthesis and Antifungal Activity of Glycosyl Isoxazolines

Abstract

Glycosyl nitrile oxides, generated in situ by reaction of glycosyl oximes (3a, 3b, 4) with N‐chlorosuccinimide and DBU, on 1,3‐dipolar cycloaddition with substituted alkenes resulted in glycosyl isoxazolines (5, 7–28) in diastereoselective manner. The extent of diastereoselection varies with the nature of substituents both in sugar and alkenes. The compounds synthesized were screened in vitro against many fungi wherein two of the compounds (12, 23) showed significant inhibition against Sporothrix schenckii, Trychophyton mentagrophytes, and Cryptococcus neoformans with MIC of 12.5 and 6.25 µg/mL, respectively.     

Heterocyclization of Orthoaminoester and Orthoamino-nitrile-thieno[2, 3-c]pyridine: The Facile Synthesis of Fused Pyridothienopyrimidines

A highly efficient and versatile synthetic approach to the synthesis of pyrido[4′, 3′: 4]thieno[2,3-d]pyrimidines (4, 14, 15, 21) and their heterofused (e.g., triazolo-, triazino-, imidazo-, and tetrazolo-,) pyridothienopyrimidines (5–9, 16, 17, 22–24) is described utilizing 2-amino-3-cyano-4,5,6,7-tetrahydro-thieno[2,3-c]pyridine-6-carboxylic acid ethyl ester ( 2 ) and diethyl 2-isothio-cyanate-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3,6-dicarboxylate ( 10 ) as starting materials.     

A Convenient One-Pot Completely Stereoselective Synthesis of trans-4-Hydroxystilbenes and Its Derivatives and X-Ray Structure of Its Precursor

Abstract

The synthesis of E-isomer of 4-Hydroxystilbene and its derivatives 3 by reductive elimination of the carbonyl function in 2-phenyl-1-(4-hydroxyphenyl)ethan-1-one and its derivatives 2 and the X-ray structure of 2a are described.