New heterocyclic ring systems. IX. Polyazadithiasteroid analogues

The synthesis of the novel tricyclic ring 5-rnethyl-4-oxo-2,3,4,5-tetrahydrothiopyrano[3,2-c]-[1,2]benzothiazine 6,6-dioxide (III) is described. By the reaction of hydrazine and hydroxylamine with the glyoxylate (IV) and ester (V) obtained from III, several polyazadithiasteriod analogues have been synthesized.     

New heterocyclic ring systems. XIII. 7,11-Dithiaazasteroid analogues

Synthesis of the tittle compounds has been achieved starting with the new tricyclic ring, 6-methyl-4-oxo-3,4-dihydro-2H,6H-thiopyrano[3,2-c][2,1]benzothiazine 5,5-dioxide (III). This compound was converted to the glyoxylate VI, the β-ketoester IX, a difluoride complex XIII and an enamino ketone XXIV which, by hydrazine, hydroxylamine and glycine treatment, gave 7,11-dithiaazasteroid analogues. Some unexpected products were also obtained from the ketone XVIII and the β-diketone XIX by treatment with chloroacetone and hydrazine respectively.     

New heterocyclic ring systems from α-hydroxymethyleneketones. X Thiadiazasteroid-related compounds

Some thiadiazasteroid analogues have been synthesized by the reaction of 3-hydroxymethyl-enebenzo[h]thiochroman-4-one with hydrazine and substituted hydrazines, semicarbazide and thiosemicarbazide. Pmr data supporting the structural assignments have been discussed.     

Molecular associations of hydrazones of heterocyclic systems. XI

Complexes of hydrazones of heterocyclic compounds with organic acceptors are investigated through the evaluation of spectroscopic and thermodynamic properties. Values of the formation constants and comparison between uv-visible and ft-ir determinations on liquid and solid phases indicate these systems are weak complexes. Contributions from hydrogen bonding and the effects of π?π* or n?π* transitions on the spectroscopic and thermodynamic properties of the complexes are discussed.     

New heterocyclic ring systems. XII. Synthesis of [1,4]thiazinocarbazoles

Five [1,4]thiazinocarbazoles have been synthesized from 6-, 7- and 8-amino-2H[1,4]benzo-thiazin-3(4H)ones by the Jaap-Klingemann reaction with 2-hydroxymethylenecyclohexanone followed by Fischer indolisation of the resulting hydrazones. The structures of the hitherto unknown ring systems have been confirmed by pmr spectral data.     

Heterocyclic studies: New heterocyclic ring systems from isomeric dimethyl diaminophthalates

The synthesis and reactions of dimethyl 3, 4- and 4, 5-diaminophthalate 7 and 9 were investigated. The condensation of these isomeric diaminophthalates and their respective nitroacetamido precursors have been shown to give rise to a variety of five, six and seven membered heterocyclic ring system. Several new tetraazanthracenes have also been prepared in this sequence.     

Synthesis of fused purinoquinazolines. Three new heterocyclic ring systems

The Ullmann reaction of 8-aminotheophylline or 8-aminocaffeine with 2-chlorobenzoic acid and of 8-bromotheophylline with ethyl-2-aminobenzoate afforded derivatives of three new heterocyclic systems: purino[7,8-α]quinazoline-5,9,11(6H,8H,10H)-trione, purino[8,9-b]quinazoline-2,4,11(1H,3H,5H)-trione and purino[8,7-b]quinazoline-2,4,6(1H,3H,11H)-trione, respectively.     

Sigma-polarization in 5-membered heterocyclic ring systems

Extended Hückel calculations on the 5-membered heterocyclic molecules furan, pyrrole, imidazole, pyrazole, 1,2,3-triazole, and the four possible oxadiazoles suggest a significant polarization of the -framework. This -polarization appears to follow simple electronegativity considerations. The calculated -polarizations are independent of, and may be opposed to, the corresponding -polarizations. For furan and pyrrole the above results reproduce the different direction of the experimental dipole moments of these two molecules. A good correlation is observed between the total (+) calculated electron densities and the experimental proton and carbon-13 chemical shifts in all of the systems studied.

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Zusammenfassung Rechnungen mit der erweiterten Hückel-Methode über die Fünferheterozyklen Furan, Pyrrol, Imidazol, Pyrazol, 1,2,3-Triazol und die vier möglichen Oxadiazole lassen eine beträchtliche Polarisation des -Gerüsts vermuten. Die -Polarisation scheint einfachen Elektronegativitätsbetrachtungen zu folgen. Die -Polarisation ist unabhängig von der entsprechenden -Polarisation und kann entgegengesetzt gerichtet sein. Für Furan und Pyrrol reproduzieren die oben genannten Ergebnisse die verschiedenen Richtungen der experimentellen Dipolmomente beider Moleküle. Eine gute Korrelation wird zwischen der gesamten ( +)-Elektronendichte und der experimentellen chemischen Verschiebung für Protonen und C¹³ in allen Systemen beobachtet.

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Résumé Des calculs par la méthode de Hückel étendue portant sur les molécules à cycle pentagonaux: furane, pyrrole, imidazole, 1,2,3 triazole et les quatre oxadiazoles, suggèrent l'existence d'une polarisation significative du squelette . Cette polarisation apparaît en accord avec de simples considérations d'électronégativité. Les polarisations calculées sont indépendantes des polarisations correspondantes et peuvent leur être contraires. Pour le furane et le pyrrole les résultats ci-dessus reproduisent les directions différentes des moments dipolaires expérie mentaux des deux molécules. On observe une bonne corrélation entre les densités totales (+) calculées et les déplacements chimiques expérimentaux du proton et du carbone 13 dans tous les systèmes étudiés.

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This work was supported by a grant from the University of Puerto Rico. It was presented at the Fourth Caribbean Chemical Symposium, January 3–7, 1967, Kingston, Jamaica.The Puerto Rico Nuclear Center is operated by the University of Puerto Rico through a contract with the U. S. Atomic Energy Commission.     

Synthesis of purinobenzothiazine and pyridothiazinopurine derivatives. Two new heterocyclic ring systems

The synthesis of derivatives of two new heterocyclic systems, purino[8,7-b][1,3]benzothiazine and pyrido[3′,2′:5,6][1,3]thiazino[3,2-f]purine, was effected by the Ullmann reaction between 8-mercaptotheophylline or 8-bromotheophylline with the appriopriately substituted benzoic or nicotinic acid, respectively. The 8,8′-dithiobistheophylline is also reported.     

Synthesis of some heterocyclic ring systems based on pyridazine

Ethyl pyridazine-3-carboxylate is used to synthesize previously unknown pyridazine derivatives.     

The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 6. Naphthothienonaphthyridines

Five novel polycyclic heterocyclic ring systems are reported via photocyclization. The specific final products in these ring systems are: naphtho[1′,2′:4,5]thieno[2,3-c][1,8]naphthyridin-6(5H)-one ( 5 ), naphtho-[1′,2′:4,5]thieno[2,3-c][1,6]naphthyridin-6(5H)-one ( 6 ), naphtho[1′,2′:4,5]thieno[2,3-c]-1,5-naphthyridine ( 9 ), naphtho[1′,2′:4,5]thieno[2,3-c][1,2,4]triazolo[4,3-a]-1,5-naphthyridine ( 12 ), and naphtho[2′,1′:4,5]thieno[2,3-c]-1,5-naphthyridine ( 17 ). The direction of photocyclization to produce 9 was established from a zero quantum two-dimensional nmr spectroscopy experiment (ZQCOSY) using 6-chloronaphtho[1′,2′:4,5]thieno[2,3-c]-1,5-naphthyridine ( 8 ) as the model compound.     

New helerocyclic ring systems from α-llydroxymethylenekelones. VIII. Polyuzasteroidal analogues of equilenin

Some 6, 15,16-triazasteroidal analogues of Equilenin carrying a 7-methyl substituent have been synthesized from 4-methyl-7-methoxy-10,11]-dihydroisoxazolo[5,4-i]phenanthridine (III).     

New tellurium-containing ring systems

The recent discovery of a suitable synthesis of the monoanionic ditelluroimidodiphosphinate ligands [TePR₂NPR₂Te]⁻ (R = Ph, ⁱPr, ^tBu) has facilitated investigations of the fundamental chemistry of these chelating inorganic ligands. This article is focused on aspects of that chemistry in which the behaviour of this ditelluro PNP ligand differs from that of the well-studied dithio and diseleno congeners. The emphasis is on new tellurium-containing ring systems formed in: (a) redox transformations and (b) the synthesis of metal complexes.     

Molecular modelling,synthesis, and antimalarial potentials of curcumin analogues containing heterocyclic ring

The molecular modelling approach was applied to a series of nineteen curcumin analogues to find the possible PfRIO2 kinase inhibitory action. A putative active site in flexible loop (S1) of PfRIO2 kinase was explored computationally to recognize the molecular basis of ligands binding. The ligands (curcumin analogues; 3a–3s) were well accommodated in the selected active site (S1) due to their higher molecular size and length. Further all these synthesized compounds (3a–3s) were evaluated for their in vitro antimalarial activity according to the reported method. The antimalarial data showed that all these compounds to have parasiticidal activity with minimum killing concentrations (MKCs) range between 3.87 and 25.35 μM and schizonticidal activity with IC₅₀ range between 1.48 and 23.09 μM. The compound 3p showed the most significant result with maximum schizonticidal (IC₅₀; 1.48 ± 0.10 μM) and parasiticidal activities (MKC; 3.87 ± 0.36 μM) could be identified as promising lead for further investigations.     

Synthesis of novel bis‐condensed heterocyclic ring assembly systems

The novel bis‐condensed heterocyclic systems with ring assemblies based on peripheral barbituric acid rings and central pyran, pyridine and thiine rings have been generated by the reaction of terephthalaldehyde and isophthalaldehyde with barbituric acid for comparison with the analogous systems generated with said dialdehydes and 1,3‐cyclohexanedione.     

Stereoselective reduction of bicyclic acetals. A method for reductive generation of heterocyclic ring systems

A new synthetic process for the construction of oxygen-containing heterocyclic systems starting from bicyclic acetals is described.     

Ring transformations of heterocyclic compounds. XI. 2,4,6-triarylphenylquinolinium salts from methyl substituted derivatives via (thio)pyrylium ring transformations

The preparation of hitherto unknown 2,4,6-triarylphenyl substituted quinolinium perchlorates 3 from methylquinolinium derivatives 2 by a 2,6-[C₅+C] ring transformation of 2,4,6-triaryl(thio)pyrylium salts 1/4 in the presence of triethylamine/acetic acid is described. Spectroscopic data of the quinolinium perchlorates 3 and their formation via anhydrobases of the salts 2 are discussed.