A practical synthesis of new S,N-disubstituted derivatives of 5-(4-methylpiperidino)methyl-2-thiouracil

5-(4-Methylpiperidino)methyl-2-thiouracil (1) has been obtained via the Mannich reaction between 2-thiouracil, paraformaldehyde, and a cyclic secondary amine such as 4-methylpiperidine (4-MP) in ethanol. New S,N(1)-di-o-(m- and p-)bromo-(nitro-) benzyl-substituted derivatives have been synthesized successfully in the reactions of 1 with the corresponding o-(m- and p-)bromobenzyl bromides or o-(m- and p-) nitrobenzyl chlorides in DMF solution in the presence of K₂CO₃. The opposite method of synthesis, that is, the reaction between 2-o-(m- and p-)bromobenzylthio-1-o-(m- and p-)bromobenzyluracils and 2-o-(m- and p-)nitrobenzylthio-1-o-(m- and p-) nitrobenzyluracils (8), with paraformaldehyde and 4-methylpiperidine in ethanol failed, indicating the important role of the enol form of 2-thiouracil for the Mannich reaction to be successful.     

Electrochemical study and analytical applications for new biologically active 2-nitrophenylbenzimidazole derivatives

The present study addresses the electrochemical behavior and the analytical applications of six 2-nitrophenylbenzimidazole derivatives with activity against Trypanosoma cruzi. When studied in a wide range of pH, by differential pulse polarography, tast polarography and cyclic voltammetry, these compounds exhibited two irreversible cathodic responses. With analytical purposes, the differential pulse polarography mode was selected, which exhibited adequate analytical parameters of repeatability, reproducibility and selectivity. The percentage of recovery was in all cases over 99%, and the detection and quantitation limits were at the level of 1 × 10⁻⁷ mol L⁻¹ and 1 × 10⁻⁶ mol L⁻¹, respectively. In addition, the differential pulse polarography method was successfully applied to study the hydrolytic degradation kinetic of one of the tested compounds. Activation energy, kinetic rate constants at different temperatures and half-life values of such application are reported.     

Synthesis of novel, potentially biologically active dibenzosuberone derivatives

Novel representatives of the important group of biologically active dibenzosuberone derivatives were prepared: 3,7-dibromo-5-(dimethylaminoethyl- oxyimino)-10,11-dihydro-5H-dibenzo[a,d]cyclohepta-1,4-diene (1), 3,7-dibromo-5-(3- dimethylaminopropylidene)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene (2) and 1,7- dibromo-5-(3-dimethylaminopropylidene)-10,11-dihydro-5H-dibenzo-[a,d]-cycloheptene (3). These compounds are potential tricyclic antidepressants (TCAs), which are still the most frequently prescribed antidepressants in many countries.     

A practical synthesis of S-quinuclidine-2-carboxylic acid and its enantiomer

A short and convenient synthesis of (S)- and (R)-quinuclidine-2-carboxylic acids has been developed. The resolution of enantiomers has been accomplished by both chemical and enzymic means.     

A study of polychlorinated leucine derivatives: synthesis of (2S,4S)-5,5-dichloroleucine

The first total synthesis of (2S,4S)-5,5-dichloroleucine has been achieved in 11 steps from l-pyroglutamic acid. A key step is the dichlorination process on the hydrazone of aldehyde 13 with CuCl₂ in triethylamine.     

Synthesis and spectroscopic studies on organotin derivatives of biologically active Schiff bases

Some five- and six-coordinated di- and tri-n-butyl tin(IV) complexes of the type Bu₂SnL, Bu₂SnL₂ and Bu₃SnL (where L is the anion of a monofunctional bidentate or bifunctional tridentate Schiff base) have been synthesized and characterised on the basis of microanalyses, molecular weight determinations, IR, NMR (¹H, ¹³C, ¹¹⁹Sn) and ¹¹⁹Sn Mössbauer spectroscopy. These complexes are highly active towards bacteria.     

Synthesis of some new biologically active coumarin derivatives

The reaction of 4-hydroxycoumarin in toluene with a variety of aromatic binucleophilic compounds has been studied. 3-(Dimethylaminomethylene)chromane-2,4-dione was used as a key intermediate for the preparation of bis[N-(4-oxocoumarinylmethylene)]-1,4-diamines. Alternative synthetic procedures and antibacterial activity data of some of the new compounds are given. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 361–366, March, 2006.     

Synthesis of biologically active derivatives of 2-aminobenzothiazole

Chemistry of Heterocyclic Compounds - The minireview considers the current trends in the synthesis of some biologically active compounds based on 2-aminobenzothiazole. The presented information...     

Microwaves in organic synthesis: Facile synthesis of biologically active pyridazinone and iminopyridazine derivatives

Condensation of Wittig reagents 1a,b with arylhydrazones 2a,b by conventional and by microwave heating techniques furnished the corresponding pyridazines 3a‐e . The arylhydrazones 7a,b were allowed to react with 1a,b under the same conditions to produce the pyridazinones 10a,b and iminopyridazines 11a,b respectively. On the other hand, the arylhydrazones 12a‐c reacted with 1a to afford the pyridazinones 13a‐c . Treatment of 3b with dimethylformamide dimethyl acetal (DMFDMA) produced the adduct 15 . The utility of microwave heating technique led to the reduction of the reaction times to few minutes and to the improvement of the yields of the products. The in vitro biological activity of some newly prepared compounds against four types of fungi was studied.     

A study of the biologically active conformers for prodine opiates and their derivatives

Conformational energy calculations using the empirical MM 2 (molecular mechanics II) and semiempirical quantum mechanical PCILO (perturbative configuration interaction using localized orbitals) methods are reported for various prodine derivatives. These include 3-demethylprodine, α-prodine, β-prodine, the α-2-methyl derivative, α-promedol, the γ-2,3-dimethyl derivative, and γ-isopromedol. The results are consistent with all of the compounds activating the opiate receptor in a phenyl equatorial conformation with optimum activity resulting from a particular orientation of the phenyl and propionoxyl groups. In disagreement with previous limited experimental data, α-promedol is found to prefer a phenyl equatorial conformer. It is confirmed that, of the two mirror image phenyl equatorial conformers that are preferred for 3-demethylprodine, the more active prodines antipodes consistently prefer the one in which the phenyl orientation is the opposite (mirror image) of that found in morphine and in the preferred conformer of the morphine-like (+)-phenylmorphan. This is a possible molecular basis for the nonmorphine-like effects that occur with the introduction of a phenyl meta hydroxyl into some prodine derivatives. It is also suggested that the less active prodine antipodes, which have a morphine-like phenyl orientation, may act in a morphine-like manner at opiate receptors.     

An efficient synthesis of rearranged new biologically active benzimidazoles derived from 2-formyl carvacrol

Research on Chemical Intermediates - A new series of benzimidazole derivatives was synthesized by one-pot two-step reaction as a result of unexpected rearrangement during reaction of 2-formyl...     

A new synthesis of highly functionalized 2H-pyran derivatives

Ethyl oxo-(2-oxo-cycloalkyl)-ethanoates undergo a smooth reaction with triphenylphosphine and dialkyl acetylenedicarboxylates via intramolecular Wittig reaction to produce spiro-cyclobutene derivatives. These spiro systems undergo electrocyclic ring opening reaction to produce electron-deficient 1,3-dienes, which spontaneously cyclize to 2H-pyran derivatives.     

A two-step practical synthesis of dehydroalanine derivatives

A two-step practical synthesis of dehydroalanine derivatives from commercially available starting materials is reported. The approach comprises an Ugi four-component reaction using 2-benzoylacetaldehyde, followed by an elimination process of the benzoate group. This protocol provided access to several dehydroalanine derivatives modified with diverse functional groups, which might be useful for further transformations in the construction of more complex molecules.     

Synthesis, spectroscopic and cytotoxic studies of biologically active new schiff bases derived from p-nitrobenzaldehyde

Thirteen new Schiff bases derived from p-nitrobenzaldehyde were synthesized by condensation with the appropriate amines. An unusual reduction of the p-nitrobenzaldehyde to the corresponding alcohol was also observed in one of the reactions. The structures of the compounds were identified using spectroscopic techniques. Cytotoxicity for the titled compounds was studied against Brine Shrimp, used as the test animal.     

Greener approach toward synthesis of biologically active s-Triazine (TCT) derivatives: A recent update

The greener methodology to synthesize s-triazine derivatives (also known as TCT) is described, including synthesis through microwave, ultrasound, and solvent-free conditions. This review mainly focuses on reactions of TCT (2,4,6-trichloro-1,3,5-triazine) with various substituents having amine and hydroxy functionalities to give corresponding triazine derivatives under a greener approach. The results of reactions indicate that, unlike classical methods, green methods result in better yields of the product, through a rapid reaction, under mild reaction conditions, and by easy workup procedures.     

A new efficient synthesis of the biologically potent PGD2-analogue ZK118182

A highly stereoselective and practical synthetic method for ZK118182, which is chemically and metabolically stable and a biologically potent PGD₂-analogue developed by Schering AG, is reported.