Hetero Ring Research Articles

X-ray study of the hetero ring flexibility in cis-trimethylene- and tetramethylene-1,3-oxazin-2-ones and a cis-trimethylene-1,3-oxazine-2-thione [1] : The structures of cis-5,6-trimethylene-5,6-dihydro-4 H-1,3-oxazin-2(3 H)-one (I), cis-5,6-trimethylene-5,6-dihydro-4 H-1,3-oxazine-2(3 H)-thione (II) and 3-methyl- cis-5,6-tetramethylene-3,4,5,6-tetrahydro-1,3-oxazin-2-one (III)

The structures of the title compounds have been established by X-ray crystallography using direct methods. Crystals of compound I (C 7H 12NO 11) are monoclinic, space group P2 1/ c, with a = 12.013(4), b = 6.133(3), c = 9.899(4) Å, β = 100.83(2)°, Z = 4 and D c = 1.309 g cm −3. Crystals of II (C 7C 11NOS) are monoclinic, space P2 1/ n, with a = 6.291(4), b = 21.316(8), c = 6.058(1) Å, β = 102.95(3)°, Z = 4 and D c = 1.319 g cm −3. Crystals of III (C 9H 12NO 2 are also monoclinic, space group P2 1/ c, with a = 6.207(4), b = 14.365(5), c 10.474(4) Å, β = 104.30(5)°, Z = 4 and D c = 1.242 g cm −3. The structures were refined to R = 0.078 for 909 reflections of I, R = 0.049 for 1372 reflections of II and R = 0.074 for 953 reflections of III. The conformations of the hetero rings have been studied in comparison with those found in the structures of IVVII [2]. A marked influence of the five-membered carbocyclic ring on the puckering of the 1,3-oxazine moiety is shown.

The Crystal and Molecular Structure of 2,3,6,8,9-Pentaphenyl-1-thia-6-azaspiro[4.4]nona-2,8-diene-4,7-dione

Abstract The title compound crystallizes in monoclinic form, space group P21/c with a=20.810(1), b=16.000(1), c=18.131(1) Å, β=107.77(1)°, Z=8. The structure was established by the direct method and refined including all hydrogen atoms by the blockdiagonal least-squares procedure, R=0.062 for 4609 observed reflections. The heterocyclic spiran skeletons in two independent molecules have the same structure; however, four phenyl rings out of five take different conformations to the hetero rings to which they attached.

„Push‐pull”︁‐substituierte Allene, VIII. 1,2‐Bismethylencyclobutane und Pyrano‐pyrane: Dimere von unterschiedlich substituierten Donor/Akzeptor‐Allenen

Push-Pull Substituted Allenes, VIII. 1,2-Bismethylenecyclobutanes and Pyrano-pyrans: Dimers from Differently Substituted Donor/Acceptor Allenes Depending on the substituents donor/acceptor-substituted allenes dimerize to give two different classes of compounds: 1,1-diethoxy-3,3-bis(trifluoromethyl)allene (4) in a [2 + 2]-cyclodimerization gives 1,2-bismethylenecyclobutane 5 and 1,1-diethoxy-3-acylallene 13 dimerizes with substituent participation in a hetero Diels-Alder reaction and subsequent electrocyclic ring closure reaction to give pyrano 14.

Synergism of Pirimicarb and Organophosphorus Insecticides against the Resistant Rice Stem Borer, Chilo suppressalis WALKER (Lepidoptera : Pyralidae)

Synergism of carbamates and organophosphorus insecticides against an organophosphate-resistant strain of rice stem borer, Chilo suppressalis WALKER, was investigated. Although no synergism was observed with the combination of fenitrothion and each of four substituted phenylcarbamates, carbaryl, methomyl or bendiocarb, a remarkable elevation of co-toxicity was observed with the combination of pirimicarb and fenitrothion. Pirimicarb, a selective aphicide, showed a high synergistic action with all dimethylthiophosphates tested, especially with compounds having a hetero ring in their structure. However, synergism was not observed with diethylthiophosphates, phosphates and dithiophosphates other than malathion. Pirimicarb showed no synergistic action with organophosphorus insecticides against the susceptible strain.

Stereochemical studies, 88 1. Saturated heterocycles, 83 : Synthesis of stereoisomeric condensed-skeleton 2-imino-substituted 1,3-oxazines

Thiourea ( 1a - d , 2a - d ) and urea ( 3a - d , 4a - d ) derivatives have been prepared from cis - and trans -2-aminomethyl-1-cyclopentanols, and -l-cyclohexanols and their N -methyl derivatives with phenyl isothiocyanate and phenyl isocyanate, respectively. Treatment of 1 and 2 with methyl iodide and then with alkali furnished - with the exception of the cis - N -methyl derivative - 2-phenylimino-1,3-oxazines ( 5a , c , 6a - d ). The remarkable fact that the ring closure of trans -2-amino-methyl-1-cyclopentanols gives 1,3-heterocycles with trans -anellation supports the assumption that the trans -1,2-disubstituted-1,3-difunctional cyclopentanes undergo ring closure when 1,3-heterocycles with a delocalized pπ bond system are formed. With thionyl chloride the cis -urea derivatives 3a - d afforded an elimination product ( 8 ), whereas the trans isomers 4 yielded the cis oxazines 5 by inversion. 1H and 13C NMR spectroscopic studies indicated that in 5a - d , the “O-in” conformers are favoured (the methylene group of the hetero ring is equatorial , while the oxygen atom is axial ) and all 3-unsubstituted-2-phenylimino-1,3-oxazines exist exclusively in the tautomeric form with an exo CN bond.

ChemInform Abstract: OXIDATIONS WITH LEAD TETRAACETATE. V. OXIDATIONS OF 1,3‐BENZOXATHIOLES

AbstractDurch Kondensation des Mercaptophenols (I) mit den Ketonen (II) werden die Benzoxathiazole (III) dargestellt.

Direct fusion of a triazine to a pyrazine ring. Synthesis of derivatives of [1,2,4]triazino[5,6-b]quinoxaline

Derivatives of heterocyclic systems containing condensed triazine and pyrazine rings are known -pyrazino[l,2-a][l,3,5]triazines [2] and [l,2,3]triazino[3,4-a]quinoxalines [3], a nitrogen atom being common to the two condensed hetero rings in both cases. Systems in which the triazine and pyrazine rings have two carbon atoms in common were not described in the literature until very recently. Only at the end of 1983 did a communication appear on the formation of [l,2,4]triazino[5,6-b]quinoxalines in the thermolysis of formazans [4].

Application of isatoic anhydride chemistry to the synthesis of racemic paraensine

AbstractThe alkaloid paraensine was obtained in racemic form in 84% overall yield by a two step reaction sequence which involves a hetero ring opening of N‐methylisatoic anhydride with the lithium enolate of 4,5‐di‐hydro‐4,5,5‐trimethyl‐2(3H)‐furanone followed by a thermal cyclization.

Radical cation formation and crystal structure determination of 4′‐dimethylamino‐10‐phenylpyrido[3,2‐b]benzothiazine

AbstractThe crystal structure of title compound, 4, shows that the 10‐aryl group is parallel to the plane bisecting the pyridobenzothiazine ring. This structure is in contrast to that normally found for phenothiazines substituted with electron‐withdrawing substituents on the 10‐phenyl ring. In those compounds, the 10‐aryl group is perpendicular to the plane bisecting the phenothiazine ring. The esr spectrum of the cation radical of 4 shows that the radical is located on the hetero ring system which is opposite to that of the cation radical of 4′‐dimethylamino‐10‐phenylphenothiazine in which the radical is located on the 10‐aryl ring.

~(13)C NMR SUBSTITUENT EFFECTS IN A SERIES OF 2-PHENYL BENZOTHIAZOLES

According to ~(13)C NMR determinations and analyses of 14 compounds of 2-phenyl benzothiazole, we have studied the substituent effects on aromatic hetero rings. The different substituents have effects on the charge densities in the molecules. We have also analyzed the structural factors of effects on ~nJ_(13C-1H). The perturbations of benzothiazole to benzene ring were studied by the method of comparison analysis. The substituent induced chemical shifts of benzothiazole were obtained. The experiential calculations of ~(13)C chemical shifts for aromatic carbons have been done, the calculated velues agreed with the experimental ones. The theoretical calculations for the compounds 2, 3, 9 have been made using the EHMO method (the Enlarged Hiickel Molecular Orbital Method). The relationships between the ~(13)C experimental chemical shifts and the total charge densities of the corresponding carbon atoms were obtained by the regression analysis. The correlation coefficient is—0.96.

An X-Ray Analysis on Restricted Rotational Isomers of 2-Thioxo-4-oxazolidinone

Abstract The thermodynamically more stable diastereomeric rotational isomer I, of 3-(o-tolyl)-5-methyl-2-thioxo-4-oxazolidinone, which is first crystallized out in solution, shows that the ortho methyl substituent is cisoid to the methyl group of the hetero ring, and the thermodynamically less stable isomer II, crystallized later, has both methyl groups in transoid conformation, as is found in X-ray studies. The carbonyl and thiocarbonyl bonds are found to be longer in isomer II than in isomer I, which is attributed to the favored conjugation interaction of carbonyl, thiocarbonyl groups with the lone pair electrons of nitrogen, that may cause the lessened stability of isomer II.

Configuration and NMR study of tricyclic oxazines fused to a norbornene or norbornane skeleton

AbstractTricyclic oxazines fused with norbornane or norbornane were synthesized for pharmacological and stereochemical purposes. Analogous oxazin‐2‐ones and ‐2‐thiones were also obtained. The diendo or diexo anellation of the hetero ring to the norbornene or norbornane skeleton was confirmed by 1H and 13C spectral data. The assignment of the proton signals was proved and the proton‐proton coupling values were determined by double resonance experiments. With mono‐ and dichloroacetyl chloride, the oxazines fused to norbornene gave azetidinones which are mixtures of two isomers. The mixtures were separated into homogeneous substances, the configuration and conformation of which were determined via differential NOE experiments.

Conformational and Spectral Investigations of Thiazolidinone Derivatives by1H and13C NMR Spectroscopy

Abstract The magnetic non-equivalence of isomeric proton and 13C nuclei has been investigated on rotational isomers of 3-aryl-2,4-thiazolidinediones and 3-aryl-2-arylimino-4-thiazolidinones. The detection of magnetic non-equivalence for proton nuclei was better in quinoline solutions. Free energies of activation have been estimated. The varying hetero atom in the hetero ring, in comparision to earlier data1–3, is seen to effect the additive shift parameters and the shielding of distant aryl carbon bonded to hetero ring.

Investigation of aryl oxazolidinones and aryl thiazolidinethiones by NMR spectroscopy

The 1H and 13C resonances of 3-aryl-2-oxazolidinones and 3-aryl-2-thiazolidinethiones have been examined. The conformational isomers of restricted rotation about the aryl CN bond could not be detected for both of the nuclei. The additive shift parameters, measured for carbon chemical shifts, are found to be higher in the sulphur substituted hetero ring.

Saturated heterocycless—35 : Synthesis and conformational analysis of stereoisomeric 2-oxo- and 2-thioxo- cis- and trans-5,6-trimethylene-3,4,5,6-tetrahydro-1,3-oxazines

cis- and trans 5,6-Trimethylene-3,4,5,6-tetrahydro-1,3-oxazin-2-ones ane 2 thiones ( 11– 20) were synthesized from cis and trans-2- aminomethylcyclopentanols ( 6– 10) by reaction with urea ethyl chloroformate, carbon disulphide or thiophosgene. The cyclization reactions were also successful with the trans-amino-alcohols, at variance with earlier literature data relating to 1,2-disubstituted 1,3-bifunctional trans-cyclopentane derivatives X-Ray diffraction analysis of trans-5,6-trimethylene-3,4,5 6-tetrahydro-1,3 oxazine-2-thione ( 17) shows that the exocyclic CXXXS sp 2 bond takes part in a co-planar delocalized pπ-pπ bond system formed on the S(10) O(1), N(3) and C(2) atoms and consequently both the C(2)-N(3) [1.304(7)å] and C(2)-O(1) [1.337(7)å] bonds gain some multiple bond character. The endocyclic bond angles at C(2) and N(3) are significantly opened, compared with those in related heterocycles. Of the bonds in the six membered hetero ring, C(5)-C(6) is significantly shortened [1.448(9)å] The remarkable ring-closure reaction of the trans cyclopentane derivatives can be explained by the above findings. 1H NMR data on compounds 11– 20 suggest conformationally homogeneous systems and the predominance of the O-inside conformers of the cis isomers.

ChemInform Abstract: ABSORPTION SPECTRA OF 2‐STYRYL‐4‐PHENYLTHIAZOLE ETHIODIDES IN ORGANIC SOLVENTS OF VARYING POLARITIES AND DETERMINATION OF THE FORMATION CONSTANT OF THE CHARGE TRANSFER COMPLEX FORMED

AbstractDie Elektronenanregungsspektren der Titelverbindungen (I) in den Lösungsmitteln CHCl3, EtOH, DMF‐ und DMSO werden untersucht und die Banden zugeordnet, wobei der Einfluß der Substituenten, der Konzentration und der Temp. diskutiert wird.

Metabolism of 7,8-dichloro-1,2,3,4-tetrahydroisoquinoline, a phenylethanolamine N-methyltransferase inhibitor. II. Species difference in metabolism and synthesis of its metabolites.

1. 7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline (DCTQ), a potent reversible inhibitor of phenylethanolamine N-methyltransferase, was well absorbed, readily metabolized and excreted mainly in urine. 2. Its pathways of metabolism in rats and dogs were markedly different. In the dog, N-methylation was followed by N-oxidation to give the corresponding N-methyl-N-oxide as the final metabolic product. This was not observed in the rat. 3. In the rat, major pathways are aromatization of DCTQ to the corresponding isoquinoline and subsequent hydroxylation in the hetero ring to all three possible isomeric hydroxy-isoquinolines. 4. Authentic metabolites were synthesized for comparison with metabolites isolated from urine.

鎮痙剤の研究(第7報)N-Alkyl Diarylmethylenequinolizidinium Bromides, N-Alkyl Diarylmethyleneindolizidinium Bromidesおよび関連化合物の構造活性相関

As a part of studies on antispasmodics, the structure-activity relationship was examined in N-alkyl diarylmethylenequinolizidinium bromides and N-alkyl diarylmethyleneindolizidinium bromides (6-33), which can be classified in to γ-substituted piperidine, β-substituted piperidine and β-substituted pyrrolidine. Compounds (6-33) exhibited potent anticholinergic activity due to having conformationally rigid bicyclic hetero rings compared to monocyclic antispasmodics such as diphemanil methylsulfate (1), timepidium bromide (2), prifinium bromide (4) and their unmodified compounds (3 and 5). Several compounds among them exhibited potent anticholinergic activity greater than that of atropine.

Stereochemical studies—XXXVII: Saturated heterocycles—XIII Configuration and conformation of Z‐ and E‐N‐methyl‐ and ‐N‐ benzyl‐2‐p‐nitrophenyl‐4,5‐ and ‐5,6‐tetramethylenetetrahydro‐1,3‐oxazines

AbstractThe configuration and conformation of Z‐ and E‐N‐methyl‐ and ‐N‐benzyl‐2‐p‐nitrophenyl‐4,5‐, and ‐5,6‐tetramethylenetetrahydro‐1,3‐oxazines were determined by 1H and 13C NMR spectroscopy. The Z isomers were proved to be conformationally homogeneous, having the heteroatom in axial and equatorial position, respectively, in the case of the 5,6‐ and 4,5‐tetramethylene compounds. Consequently, the p‐nitrophenyl group and the anellated cyclohexyl ring are all‐cis arranged in the Z‐5,6‐tetramethylene compounds while in the case of the Z‐4,5‐tetramethylene isomers the p‐nitrophenyl group and the cyclohexyl ring are trans arranged to the hetero ring.

Absorption spectra of 2-styryl-4-phenyl-thiazole ethiodides in organic solvents of varying polarities and determination of the formation constant of the charge transfer complex formed

The electronic absorption spectra of some 2-styryl-4-phenyl-thiazole ethiodides are studied in organic solvents of different polarities. The shorter wavelength band appearing in the visible region is assigned to an intramolecular charge transfer (CT)-transition originating from the phenyl moiety to the positively charged hetero ring, while the longer wavelength one is due to an intermolecular CT-transition from the iodide ion to the 2-styryl-4-phenyl-thiazolinium cation. These assignments are based on the nature of the aldehydic residue and effects of solvent, concentration, and temperature on both the position and absorptivity of the CT complex-band. It is concluded that the CT complex formed will be highly solvated inDMF, DMSO, ethanol and methanol relative to in CHCl3, dioxane and acetone. The formation constant of the CT complex in solutions of different polarities is determined at different temperatures. Furthermore, the thermodynamic parameters ΔH o, ΔG o and ΔS o for complex formation are calculated and discussed.