Synthesis of novel pyridocoumarins and benzo-fused 6-azacoumarins

Benzo[7,8]-fused 6-azacoumarins are prepared from 4-quinolinol by treatment with PPh₃ and DMAD, or from 3-formyl-4-quinolinol by Wittig reaction with carbalkoxyalkylidene(triphenyl)phosphoranes. Angular pyridocoumarins are prepared from 8- or 6-quinolinols with PPh₃ and DMAD, or from the reactions of 5,6- or 7,8-quinolinediones with carbalkoxymethylene(triphenyl)phosphoranes.     

Synthesis of novel 6-substituted sulfur-containing derivatives of pyridoxine

An efficient synthesis of novel 6-substituted derivatives of pyridoxine was achieved. The reactions of various thiols with mono-, bis-, and tris(сhlorine) derivatives of 6-methyl-2,3,4-tris(hydroxymethyl)pyridin-5-ol (6-hydroxymethylpyridoxine) gave sulfur-containing derivatives of pyridoxine.     

Synthesis of a novel C-6 nigrogen-substituted carbapenem from 6-aminopenicillanic acid

Synthesis of optically active 6-phthalimidocarbapenems from 6-aminopenicillanic acid is described.     

Synthesis of novel rigid triazine-based calix[6]arenes

In this report, the stepwise synthesis of a novel rigid and functionalised macrocycle 2 based on triazine and phenylenediamine linkers, is presented. Poor recognition of the macrocycle 2 for its substrates is observed, which shows experimentally that for the meltriazine based-calix[6]arene system, the binding ability of the melamine moiety gets more benefit from the ring flexibility derived from a xylenediamine linker 1 than from a phenylenediamine linker 2.     

Synthesis and antiviral evaluation of novel N-6 substituted adenosine analogues

A series of adenosine analogues were synthesized and their biological evaluation was tested against Coxsackie virus B3 (CVB3) and Herpes simplex virus type 1(HSV-1) in HEp-2 cells. The hydrophobic constant, acute toxicity, carcinogenicity and mutagenicity were calculated. Analogues with piperazine derivatives 8b showed promising activities against CVB3 with a lower IC₅₀value and higher selectivity index, their efficacy was better than that of the commercialized medicine, Ribavirin. These described adenosine analogues exhibit potent antiviral activities against several viruses, and offer new leads for further development.     

Synthesis and characterization of novel calix[6]phyrin derivatives

Three novel calix[6]phyrin derivatives have been synthesized by reaction of corresponding tripyrrane with aromatic aldehyde. The reaction condition was optimized and the structures of these compounds have been characterized by NMR and MS.     

Pyrazoles. 6. Synthesis of novel heteroaryl 4-pyrazolyl ketones

The preparation of a variety of novel heteroaromatic analogues of benzophenone 2–11 characterized by a 4-pyrazolyl moiety and a thienyl-, azinyl- or diazinyl-system starting from 1,4-dilithiopyrazole is reported.     

Synthesis and antitumor evaluation of novel derivatives of 6-amino-2-phenylbenzothiazoles

Novel derivatives of 6-amino-2-phenylbenzothiazole bearing different substituents (amino, dimethylamino or fluoro) on the phenyl ring were prepared as the corresponding hydrochloride salts. 6-Nitro-2-(substituted-phenyl)benzothiazoles (1-6) were synthesized by condensation reactions of substituted benzaldehydes with 2-amino-5-nitrothiophenol. Nitro derivatives were reduced to the amino derivatives with SnCl(2)/HCl.Water soluble hydrochloride salts of 6-amino-2-(substituted-phenyl)benzothiazole (13-19)were prepared using concentrated or gaseous HCl. Compounds 13-19 were found to exert cytostatic activities against malignant human cell lines: cervical (HeLa), breast (MCF-7),colon (CaCo-2), laryngeal carcinoma (Hep-2), and normal human fibroblast cell lines (WI-38).     

Synthesis of 6-substituted 6-nitroperhydro-1,4-diazepines via novel tandem retro-Henry and Mannich/Michael reactions

N,N'-Dibenzyl-6-hydroxymethyl-6-nitroperhydro-1,4-diazepine was converted into a nitronate via retro-Henry reaction, followed by either Michael reaction with several acrylic derivatives or Mannich reaction with different amines, thus leading to 6-substituted 6-nitroperhydro-1,4-diazepines. The tandem retro-Henry/Mannich reaction was also carried out using benzylamine as base, solvent, and reagent at the same time. Selective hydrogenation of the nitro group and complete hydrogenolysis were also successfully achieved.     

Synthesis of bastadin-6 trimethyl ether,a novel 28-membered ring lactam

Bastadin-6 trimethyl ether, a 28-membered ring lactam, was synthesized by means of phenolic exidation of dibromobastadin-2 trimethyl ether with thallium (III0 nitrate (TTN) leading to the formation of the corresponding macrocyclic biphenyl ether as a key step. From bastadin-2 trimethyl ether, a 26-membered ring compound was also synthesized.     

Synthesis and structure of a novel molybdenum imido calix[6]arene

Treatment of p-tert-butylcalix[6]areneH₆ (H₆L) with [Mo(OBu^t)₂{[2,2′-(N)-C₆H₄]₂(CH₂CH₂)}] in refluxing toluene affords, after work-up, the complex [Mo(2-NC₆H₄CH₂CH₂C₆H₄NHC(Me)NH-2^/)LH₂]·4MeCN (1), which contains an 11-membered metallocyclic ring as characterised by Synchrotron X-radiation.     

Synthesis and properties of novel polyimide/nylon‐6 triblock copolymers

Nylon‐6‐b‐polyimide‐b‐nylon‐6 copolymers were prepared by first synthesizing a series of imide oligomers end‐capped with phenyl 4‐aminobenzoate. The oligomers were then used to activate the anionic polymerization of molten ϵ‐caprolactam. In the block copolymer syntheses, the phenyl ester groups reacted quickly with caprolactam anions at 120 °C to generate N‐acyllactam moieties, which activated the anionic polymerization. In essence, nylon‐6 chains grew from the oligomer chain ends. All of the block copolymers had higher moduli and tensile strengths than those of nylon‐6. However, their elongations at break were much lower. The thermal stability, chemical resistance, moisture resistance, and impact strength were dramatically increased by the incorporation of only 5 wt % polyimide in the block copolymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4247–4257, 2000     

Synthesis of 6-cyanopurines and the isolation and X-ray structure of novel 2H-pyrroles

(Z)-N¹-(2-Amino-1,2-dicyanovinyl)-N²-substituted-formainidines react with dimethylformamide diethyl acetal at room temperature to give 6-cyanopurines as the major product together with novel 5-amino-2-arylimino-3,4-di[(N,N-dimethylamino)methylideneamino]-2H-pyrroles, which have been fully characterised and a single crystal X-ray analysis has been carried out on the N-phenyl derivative.     

Two novel 18-metallacrown-6 complexes: Synthesis,structural characterization and bioactivity

Two new macrocyclic hexanuclear metal(III) 18-metallacrowns-6, [Mn₆(acshz)₆(H₂O)₆] · 18H₂O (1) and [Fe₆(acshz)₆(CH₃OH)₆] · 6CH₃OH · 6H₂O (2), have been synthesized and characterized, where acshz³⁻ is N-acetyl-5-chlorosalicylhydrazidate. These crystal structures contain neutral 18-membered metallacrown rings consisting of six metal(III) ions and six acshz³⁻ ligands. The ring is formed by the succession of six structural moieties of the type [M(III)–N–N] through hydrazide N–N groups bridging the ring metal ions. The ligand enforces the metal ions to form the stereochemistry of a propeller configuration with alternate Λ/Δ or Δ/Λ forms. The largest diameters of the hexanuclear rings are about 6.97 Å at the entrance and 9.53 Å at the centre of the cavity for 1; and 7.94 and 10.24 Å for 2, respectively. The solution integrity and stability of the metallacrowns were confirmed using electrospray ionization ESI-MS and UV–Vis spectroscopy in methanol. Antibacterial screening data indicate the formation of the metallacrown 1 reduces the antimicrobial activity of the ligand H₃acshz hugely, while metallacrown 2 has strong antimicrobial activity against Bacillus subtilis (B. subtilis).     

Synthesis of novel C6-phosphonated purine nucleosides under microwave irradiation by SNAr-Arbuzov reaction

Novel C6-phosphonated purine nucleosides were obtained in good to excellent isolated yields by the simple and catalyst-free SNAr-Arbuzov reaction of trialkyl phosphite with 6-choloropurine nucleosides, including a series of nonsugar carbon nucleosides. Shorter reaction times were needed, and substantially higher yields were obtained under microwave irradiation conditions compared with conventional heating conditions.     

Synthesis of novel symmetrical and nonsymmetrical 6-membered heterocycles with pendant electron-rich organoiron substituents

The functionalized complexes [(dppe)Cp^*Fe(CC)]₂-(Py) (Py=2,6-C₅H₃N and 3,5-C₅H₃N (dppe=1,2-bis(diphenylphosphino)ethane) were isolated in good yields from reaction of the chloro complex (dppe)Cp^*FeCl with the protected bis-acetylenic heterocyclic precursor. These electron-rich pyridyl ligands constitute interesting examples of organometallic heterocycles bearing redox-active substituents. Attempts to find an alternative route starting from the alkynyl complex [(dppe)Cp^*Fe(CCH)] and the corresponding dibromopyridines using a Sonogashira cross-coupling reaction are also described. By this route, the monofunctionalized products [(dppe)Cp^*Fe(CC)]-2,6-Py-Br and [(dppe)Cp^*Fe(CC)]-3,5-Py-Br could be cleanly isolated. These compounds open the way to the generation of heteroaromatics featuring nonequivalent alkyne substituents such as [(dppe)Cp^*Fe(CC)]-2,6-Py-[(CC)SiMe₃] or [(dppe)Cp^*Fe(CC)]-3,5-Py-[(CC)SiMe₃] by further coupling.In commemoriation of the centenary of Academician A. N. Nesmeyanov.UMR CNRS 6509 Organométalliques et catalyse: Chimie et Electrochimie Moléculaires, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1207–1218, September, 1999.     

Synthesis of novel dihydro-2H-1,2,4-oxadiazin-5(6H)-ones

The title compounds 4 were synthesized via the acid-catalyzed reaction of α-(acylaminooxy)carboxylic acid amides 6 with carbonyl compounds, and controlled catalytic hydrogenation of the resulting 2-benzyloxy-carbonyldihydro-2H-1,2,4-oxadiazin-5(6H)-ones 7 (R⁶ = PhCH₂O).     

Synthesis of novel imidazolidinones

Summary The preparation of a number of new imidazolidinones by a simple method based on the reaction of -aminocarboxamides with carbonyl compounds is described.

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Synthese neuer Imidazolidinone

Zusammenfassung Die Darstellung einer Reihe neuer Imidazolidinone durch Reaktion von -Aminocarboxamiden mit Carbonylverbindungen wird beschrieben.