Methods for syntheses of N-methyl-DL-aspartic acid derivatives.

A novel practical method for the synthesis of N-methyl-DL-aspartic acid 1 (NMA) and new syntheses for N-methyl-aspartic acid derivatives are described. NMA 1, the natural amino acid was synthesized by Michael addition of methylamine to dimethyl fumarate 5. Fumaric or maleic acid mono-ester and -amide were regioselectively transformed into beta-substituted aspartic acid derivatives. In the cases of maleamic 11a or fumaramic esters 11b, the alpha-amide derivative 13 was formed, but hydrolysis of the product provided N-methyl-DL-asparagine 9 via base catalyzed ring closure to DL-alpha-methylamino-succinimide 4, followed by selective ring opening. Efficient methods were developed for the preparation of NMA-alpha-amide 13 from unprotected NMA via sulphinamide anhydride 15 and aspartic anhydride 3 intermediate products. NMA diamide 16 was prepared from NMA dimethyl ester 6 and methylamino-succinimide 4 by ammonolysis. Temperature-dependent side reactions of methylamino-succinimide 4 led to diazocinone 18, resulted from self-condensation of methylamino-succinimide via nucleophyl ring opening and the subsequent ring-transformation.

Evaluation of CD detection in an HPLC system for analysis of DHEA and related steroids.

The biological importance of dehydroepiandrosterone (DHEA) is reflected by the fact that DHEA is a crucial precursor of the biosynthesis of the steroidal sex hormones. Simultaneous separation of DHEA, dehydroepiandrosterone sulfate (DHEA-S), pregnenolone, androstenedione and testosterone has been accomplished by reversed-phase ion-pair high-performance liquid chromatography (RP-IP-HPLC) based on isocratic elution applying circular dichroism (CD) detection at 295 nm. Addition of tetrabutylammonium hydrogensulfate to the mobile phase increases the retention of DHEA-S on the C8-silica column by an apparent ion-pairing mechanism without affecting the retention of the other (non-ionic) steroids. CD spectroscopy provides highly selective detection of compounds possessing optically active absorption bands and the separation is even more selective in the higher wavelength range applied. The linearity of the steroid concentration (c, mg mL(-1)) versus peak area was tested in the concentration range of 0.5-2 mg mL(-1) (injected quantities were 10-40 microg). The relative standard deviation (RSD) values for DHEA and DHEA-S indicated a good intra-assay and inter-assay precision of the method.

6-oxo-morphinane oximes: pharmacology, chemistry and analytical application.

The permanent therapeutic importance of morphine derivatives in pain treatment has inspired continual synthetic efforts to modify the rigid pentacyclic systems in search for new selective analgesic agents. As a result, several morphinane oximes have been synthesized recently, which have the additional advantage of possessing an oxime group that can provide a method for selective determination of opiate alkaloids in biological matrices. The oximes of hydrocodone and oxycodone have stronger analgesic effect than the parent ketones and they also proved to be effective in preventing the respiratory depressant and hypotensive actions of fentanyl. In this work a review is given on the present status of oxime pharmacology, chemistry and analysis and also the oxime and O-methyl oxime formation of 6-oxo-morphinanes with therapeutic interest (codeinone, oxycodone, hydrocodone and 14-OH-codeinone). The oxime formation was monitored by reversed-phase HPLC and the chromatographic properties of oxime isomers have been characterized. The assignation of the individual isomers isolated by preparative HPLC was performed by (1)H NMR spectroscopy based on the chemical shift differences of the 5-H signals. In this way the isomeric ratio in the oxime products could also be determined. It was found that in the case of Delta(7)-6-oxo-morphinanes, depending on the substituents, the formation of the Z-isomer highly dominates (73-96%) over that of the E-isomer. However, for the saturated 7,8-(dihydro) derivatives the E-isomer is definitely preferred (>98%). In conclusion of a survey on the theoretical background of oxime isomerism, the conformational differences between the saturated and unsaturated morphinane systems were found responsible for the different E/Z ratios. On the basis of the isomeric ratio and the on-line CD and UV spectra of the pure isomers, the molar ellipticities and absorbancies of the isomers were calculated by a parameter estimation method.

Quinazolone-alkyl-carboxylic acid derivatives inhibit transmembrane Ca(2+) ion flux to (+)-(S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid.

Comparison of the kinetics of the inward Ca(2+) ion flux to (S)-alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid [(S)-AMPA] in cerebrocortical homogenates and that of the previously reported transmembrane Na(+) ion influx mediated by an AMPA receptor in hippocampal homogenates established that the agonist-induced opening of the AMPA receptor channels occurs in two kinetically distinguishable phases. Here we report that the 2-methyl-4-oxo-3H-quinazoline-3-acetic acid (Q1) inhibits the major slow-phase response specifically, whereas the acetyl piperidine derivative (Q5) is a more potent inhibitor of the fast-phase response. Both the quinazolone-3-propionic acid (Q2) and the quinazolone-3-acetic acid methyl ester (Q3) enhanced the slow-phase response to (S)-AMPA. The information provided by docking different Q1, Q2, and Q5 models at the ligand-binding core of iGluRs were used to define agonistic and antagonistic modes of interactions. Based on the effects of quinazolone-3-alkyl-carboxylic acid derivatives on specific [(3)H]Glu binding and kinetically distinguishable Ca(2+) ion permeability responses to (S)-AMPA and molecular modeling, the fast- and the slow-phase (S)-AMPA-elicited Ca(2+) ion fluxes were corresponded to different subunit compositions and degrees of S1S2 bridging interaction relative to substitution of kainate thereupon. Substitutions of agonists and antagonists into the iGluR2 S1S2 ligand binding core induced different modes of domain-domain bridging.

[Use of crystal conversion reactions in the synthesis of pentacyclic alkaloid analogues]. / Kristály-átalakulási reakciók felhasználása pentaciklusos alkaloid analógok szintézisében.

During investigation of substitution of debenzorutaecarpine derivatives thermal cyclization reactions was observed to produce new fused heterocyclic systems. The optimal temperature of cyclizations was determined by differential calorimetric measurements of crystals of intermediate products. The thermolysis of 2-azido-3-formil-debenzorutaecarpine gave, after elimination nitrogen, izooxazolo-debenzorutaecarpine in good yield. The cyclization of the 2-azido-3-nitroso-debenzorutaecarpine readily led to oxadiazolo E-ring analogue of rutaecarpine. The thermal cyclization of 2-hydroxy-debenzorutaecarpines gave 2-oxo- and 4-oxo-pyrano E-ring analogues of rutaecarpine. The structure of substances was confirmed by spectroscopic methods. The synthesised compounds are considered as first representatives of new heterocyclic ring systems.

[Synthesis of carboline alkaloid analogues]. / Karbolinvázas alkaloid analógok szintézise.

Hybrid compounds were synthesized combining the structural features of two isomer natural indolalkaloids rutaecarpine (1) and nauclefine (2). These aza-bioisosteric analogues are the first representatives of a new heterocyclic ring system. Two alternative reaction routes were developed for the synthesis of pentacyclic compounds (4, 5) in which the key step is the Fischer indolization of the 6-phenylhydrazono-dipyrido[1,2-a;4,3-d]pirimidine-11-ones. In the case of E-ring substituted derivatives the synthesis was carried out via preparation and chemical transformation of pyrido[1,2-a]pirimidine-4-ones (14, 15) to 2-substituted-3-aza-rutaecarpines (17-20). Finally, the nucleophilic displacement of the chlorine atom of 2-chloro-3-aza-rutaecarpine (18) by dialkylaminoethylamine provided the 2-amino-substituted derivative (20) having improved physico-chemical properties and increased antitumour activity. The new compounds are characterized by UV, IR, 1H, 13C NMR spectroscopy.

Optical resolution of a series of potential cholecystokinin antagonist 4(3H)-quinazolone derivatives by chiral liquid chromatography on alpha1-acid glycoprotein stationary phase.

Optical resolution of the enantiomers of new 4(3H)-quinazolone derivatives is investigated using the alpha1-acid glycoprotein chiral stationary phase (Chiral-AGP). Stereoselective separation of the model compounds can be controlled by varying the pH and adding uncharged organic modifiers (acetonitrile and 2-propanol) to the mobile phase. For the majority of quinazolone derivatives, Chiral-AGP is proved to be an excellent enantioselector, because optimized chromatographic conditions allow for the baseline separation of the enantiomers. Separation factors between 1.19 and 1.85 are obtained. The effects of acetonitrile and 2-propanol on the chromatographic behavior of the model compounds are quite different because of their different hydrophobic- and hydrogen-bonding properties. The eluent pH and organic modifier concentration also contributes to the chiral recognition by altering the protein environment. The analysis of the experimental results leads to new information about the chromatographic mechanism on a Chiral-AGP surface.

[7-aza analogs of quinazolino-carboline alkaloids. Synthesis, structure, characterization]. / Kinazolino-karbolinvázas alkaloidok 7-aza-analóg származékai szintézis, szerkezet, jellemzés.

The synthesis, structure and characterization of 8-substituted-7-azarutaecarpines (2) is described. These compounds were prepared by Fischer indolization of 3-amino-2-(1-phenylhydrazonoethyl)-4(3H)-quinazolin-one (5), followed by cyclocondensation with a series of aliphatic or aromatic aldehydes and formic acid or a Vilsmeyer-Haack reagent. The stereochemistry of compounds (2) was investigated by 1H nmr spectroscopy. It was found that the 8-substituents assume a quasi-axial position on the flattened boat conformation of ring C of (2), with the exception of ortho substituted phenyl groups, which occupy quasi-equatorial position. Semiempirical MO calculations support these conformational preferences.

[Synthesis and investigation of protonation properties and lipophilicity of some new quinazolone-3-carboxylic acid derivatives]. / Kinazolon-3-karbonsav származékok szintézise, protonálódási és lipofilitási vizsgálata.

Several new quinazolone-carboxylic acid derivatives as potential NMDA and AMPA receptor antagonists have been synthesized, and the protonation properties and lipophilicity of some representative molecules have also been studied. The protonation macroconstants (logK) of 4(3H)-quinazolone (Q0) and two 2-methyl-4-oxo-3H-quinazoline-3-carboxylic acids (Q1, Q2) were determined by pH-potentiometry. The acid-base chemistry of Q1 and Q2, where protein-bindings take place in an overlapping fashion, was described in terms of protonation microconstants (logk) as well. Microspeciation was carried out by UV-pH titration and deductive method. Microspeciation revealed remarkable differences between the two homologue compounds (Q1 and Q2), namely insertion of a second methylene moiety into the aliphatic acid side-chain reversed the predominantly zwitterion-involved protonation pathway into neutral form-involved one. Lipophilicity of our molecules was described by the octanol-water partition coefficients. The apparent partition coefficients of Q1 and Q2 were determined by shake-flask method and converted into true logP values using the protonation microconstants. The unexpected differences between their true logP values were explained, similarly to the different protonation pathways with conformational preferences and formation of intramolecular interactions. Out of the other 15 monoprotic quinazolone compounds the lipophilicity of 10 molecules (Q8-Q17, experimental set) was determined by RP-TLC method with the help of a calibration set consisting of 12 standard molecules, five quinazolones (Q3-Q7, determined by shake-flask method) and seven pyrido[1,2a]pyrimidines (PP1-PP7). The obtained logP values proved mostly the expected structure-property relationships. These physico-chemical investigations are pieces of predictive information for the pharmacokinetics of our compounds. These are also discussed in the paper.

[Synthesis and reactivity of debenzorutaecarpine derivatives]. / Debenzorutekarpin származékok szintézise és reaktivitása.

A series of 7,12-dihydropyrimido[1',2';1,2]pyrido[3,4-b]indol-4(6H)-ones was prepared by Fischer indolization of 9-arylhydrazono-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidin-4-one s. Quantumchemical calculations (ab initio and AM1) indicate that position 3 of 7,12-dihydro-pyrimido[1',2';1,2]pyrido[3,4-b]indol-4(6H)-one can be involved in electrophilic substitutions, while position 2 is sensitive towards nucleophilic attack. Bromination of 6-methyl-7,12-dihydropyrimido[1',2';1,2]pyrido[3,4-b]indol-4(6H)-o ne (16) with bromine afforded 3-bromo derivative (25), which was reacted with cyclic amines to give 2-amino-7,12-dihydro-pyrimido[1',2';1,2]pyrido[3,4-b]indol-4(6H)-ones (26-30) in an addition-elimination reaction. Vielsmeier-Haack formylation of compound (16) give 12-formyl (31) and 3,12-diformyl (32) derivatives (an N-formyl-1-aza derivative of nauclefidine alkaloid (34) at 60 degrees C and 100 degrees C, respectively. 3,12-dformyl compound (32) was oxidized to 3-carboxyl derivative (33). The quaternary salt (35), obtained from compound (16) with dimethyl sulphate, suffered a ring opening on the action of aqueous sodium hydroxide. The new compounds have been characterized by elemental analyses uv, 1H nmr and in some cases by 13C ruler, CD spectra and X-ray investigations.

Characterization of potential NMDA and cholecystokinin antagonists I. acid-base properties of 2-methyl-4-oxo-3H-quinazoline-3-alkyl-carboxylic acids at the molecular and submolecular levels.

The protonation macroconstants (log K) of 4(3H)-quinazolone (1) and two 2-methyl-4-oxo-3H-alkyl-quinazoline-3-carboxylic acid derivatives (2,3) were determined by pH-potentiometry. The acid-base chemistry of compounds 2 and 3, where proton-bindings take place in an overlapping fashion, was described in terms of protonation microconstants as well. Microspeciation was carried out by two means: UV-pH titration (selective, pH-dependent monitoring of the N1-binding site), and deductively (using a derivative compound as covalently fixed model of one of the protonation isomers). The microconstant values obtained by the two different methods are in agreement within 0.05 log K units. Microspeciation revealed remarkable differences between the two homologue compounds (2 and 3). The microconstant values show that insertion of a second methylene moiety into the aliphatic acid side-chain (1) increases the electron-density and most basicity parameters of both functional groups; (2) significantly modifies the extent of site-site interactions in the molecule; (3) opens new conformational preferences by N1 ring nitrogen-carboxylic group intramolecular hydrogen bond formation and (4) reverses the predominantly zwitterion-involved protonation pathway into a neutral form-involved pathway. These molecules exemplify that microconstant values allow the comparative prediction and quantitative evaluation of pharmacokinetic behaviour, and signify the fact that microspeciation is a powerful tool in the process of drug development.

Characterization of potential NMDA and cholecystokinin antagonists. II. Lipophilicity studies on 2-methyl-4-oxo-3H-quinazoline-3-alkyl-carboxylic acid derivatives.

The lipophilicity of 17 newly synthesized potential NMDA and cholecystokinin antagonist 2-methyl-4-oxo-3H-quinazoline-3-alkyl-carboxylic acid derivatives has been investigated. The apparent partition coefficients of two amphoteric compounds of overlapping protonation (Q1 and Q2) were determined by shake-flask method and converted into true log P values using the protonation microconstants. The difference between their lipophilicity expressed with the true partition coefficients was less, than it could be expected from the 2D structures and was explained with conformational preferences and formation of intramolecular interactions. Out of the other 15 monoprotic quinazolone compounds the lipophilicity of ten molecules (Q8-Q17, experimental set) was determined by TLC method with the help of a calibration set consisting of 12 standard molecules, five quinazolones (Q3-Q7) and seven pyrido[1,2-a]pyrimidines (PP1-PP7). In order to justify the suitability of pyrido-pyrimidines as standards for the chromatographic log P determination of quinazolones, first Q3-Q7 were examined by TLC and HPLC using PP1-PP7 for calibration. Data showed good agreement of results obtained by shake-flask and two different chromatographic methods indicating the similar chromatographic behavior of the two bicyclic systems and the relevance of PP1-PP7 to extend the calibration set of quinazolones. The obtained log P values proved mostly the expected structure-activity relationships. Some findings, however, have revealed specific partition behavior of the compounds providing useful information in the estimation of their pharmacokinetics, and these are discussed in the paper.

[Synthesis of hetero-condensed quinazolones: 1,2,4-triazino[6,1-b]- and 1,2,5-triazino[2,3-b]quinazolones]. / Heterokondenzált kinazolonok szintézise: 1,2,4-triazino[6,1-b]- és 1,2,5-triazepino[2,3-b]kinazolonok elöállítása.

In the course of the systematic investigation of heterocondensed quinazolones derivatives of a new heterocyclic ring system, [1,2,5]triazepino[2,3-b]quinazolone have been developed as potential biologically active agents, which are new bioisoteric analogues of cholecystokinin antagonist diazepino[2,1-b]quinazolones. The authors worked out an original synthetic route for preparation of ring analogue [1,2,4]triazino[6,1-b]quinazolines from intermediates of the synthesis, too. Starting 2-alkyl-3-amino-quinazolones are easily prepared by reaction of 2-alkyl-benzoxazone with hydrazine hydrate. In the next step bromination reaction of the alpha-methylene group of 2-alkyl-substituents gave a mono-bromo derivative as major product. In the reaction of the bromo compound with N-nucleophyles 2-alkylamino-3-amino-quinazolones were obtained which reacted with alpha-halogeno-carbonyl compounds and led to the tricyclic quinazolones in ring closure reaction. The structural properties of the heterocyclic compounds were characterized by UV-VIS and NMR data and molecular modelling calculation.

Heterocondensed quinazolones: synthesis and protein-tyrosine kinase inhibitory activity of 3,4-dihydro-1H,6H-[1,4] oxazino-[3,4-b]quinazolin-6-one derivatives.

1-Benzylidene (2-14) and 1-phenylhydrazono derivatives (15-29) of 3,4-dihydro-1H,6H-[1,4]oxazino[3,4-b]quinazolin-6-one (1) were obtained from the condensation reactions of 1 with a series of aromatic aldehydes and by direct diazonium coupling with aryl-diazonium chlorides. The substances were tested for their ability to inhibit the tyrosine kinase activity of SW-620 (human colon carcinoma) cells. Compounds 8, 10, 12 and 13 showed remarkable inhibitory activity.

[Synthesis of potential CCK antagonist quinazolone derivatives]. / Potenciális CCK-antagonista kinazolon-származékok szintézise.

An original route has been found for the synthesis of [1,4]diazepino-quinazolones, a new ring system of heterocondensed quinazolones. These anthranilicacid-alanin-beta-alanin cyclopeptide derivatives constitute a structural moiety of asperlicin, the first natural cholecystokinin antagonist alkaloid. These compounds are therefore potential CCK antagonists. The new compounds were prepared via condensation of 2-amino-alkyl-quinazolones, obtained from 2-alkyl-quinazolones by side-chain substitution, with 1,3-bifunctional-reagents. We studied the cyclisation process under basic, acidic and phase-transfer catalyzed conditions. The structures of the synthesized compounds were characterized by IR, UV and NMR spectroscopy.

Two antithrombotic quinazolone derivatives.

The structures of two antithrombotic quinazolone derivatives, 1,2,3,5-tetrahydro-2-benzylimidazo[5,1-b]-quinazolin-5-one, (I), and 3-benzyl-2-[1-(2,5-xylidino)-ethyl]quinazolin-4(3H)-one, (II), display significant differences in the bond lengths in one region of the quinazolone moiety.

[HPLC-investigations of imidazoquinazolone derivatives. Part 2]. / Imidazokinazolon-származékok folyadékkromatográfiás vizsgálata. II.

In a previous paper (2) authors, reported good correlation between the HPLC (log k') and TLC (RM) retention data and the 1-octanol/water partition coefficient (log l') of imidazoquinazolone derivatives synthetized in their laboratory. In the present work the behaviour of the compounds in HPLC systems containing ion-pairing agents (camphorsulfonic acid, Na-dodecyl sulfate) has been studied. While, in reversed phase systems no change of retention indicating the formation of ion-pairs or molecule complexes was observed, camphor-sulfonic acid caused significant increase of retention in the chromatographic systems with bare silica as stationary phase. This phenomenon is interpreted by the formation of camphorsulfonic acid double layer on the silica surface and as a consequence of mixed retention mechanism. The results of a detailed study on the latter subject will be published in a next paper. Double peak formation was observed in reversed phase system in case of C1-C3 disubstituted derivatives. This was interpreted with the formation of isomeric mixtures. Theoretical considerations as well as the identical spectra of the two peaks make plausible the appearance and separation of conformational isomers.

Nitrogen bridgehead compounds. 66. Bronchodilator nitrogen bridgehead compounds with a pyrimidinone moiety.

New types of bronchodilator agents, bi- and tricyclic nitrogen bridgehead compounds with a pyrimidin-4(3H)-one ring, were synthesized and evaluated for bronchodilator activity against serotonin-, histamine-, and acetylcholine-induced spasms in the guinea pig Konzett-Rössler test. The structure-activity relationships are discussed. The effects of some bi- and tricyclic derivatives on the human bronchus were also investigated. The homologous tricyclic compounds 68 and 69 were tested on isolated guinea pig ileum and trachea, and the effects of compound 69 were investigated in pilocarpine-treated dogs. Azepino[2,1-b]quinazoline (69; CHINOIN-1289) was selected for further biochemical and clinical investigations.