摘要:

The stereochemistry of the adducts of isoquinolin-3(2H)-ones and maleimides was studied and1H and13C spectral parameters of theendoandexostereoisomers were determined. The predominant rotamers generated by rotation about the C(7)—C(7a) and (C1)—C(1′) bonds were identified.

ISSN:0008-4042    

DOI:10.1139/v85-169

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Kinetic studies of the oxidation of 2,3-dihydroxy-2-propenal (triose reductone, RH2) by hexacyanoferrate(III), [Fe(CN)6]3−, were carried out in acidic media ([H+] = 0.02–0.1 M(1 M = 1 mol dm−3)) at various temperatures (10–30° C). The ionic strength of the media (I = 0.04–0.4 M) was adjusted using sodium perchlorate. The second-order rate constants inM−1s−1are (0.86 ± 0.06) – (2.83 ± 0.14) for the reactions of hexacyanoferrate(III) with RH2, and [(4.16 ± 0.03) − (12.4 ± 0.2)] × 103for those with RH−ion. Activation parameters for the oxidation have been reported and compared with those of the oxidation of triose reductone with peroxodisulfate ion. A probable mechanism is proposed for the reaction.

ISSN:0008-4042    

DOI:10.1139/v85-170

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Monoselective and biselective spin-lattice relaxation rates, together with nOe experiments, have been used to examine the configuration and conformation of the epoxypropyl side-chain of "asperlin" (1) in benzene solution. The data confirm earlier evidence that the oxirane ring istrans, and indicate that1is the 6R, 7Sdiastereomer. Moreover, it is shown that in the most probable conformation of the side-chain about the C-5, C-6 bond, H-5 and H-6 areanti.

ISSN:0008-4042    

DOI:10.1139/v85-171

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

A synthesis of theD-norisomorphinan ring system is described. Conversion of the initial synthetic target,trans-1,3,4,9,10,10a-hexahydro-6-methoxy-9-oxo-4a(2H)-phenanthrenecarboxamide (10c) into theD-norisomorphinan (6b) proved possible only after removal of the carboxamide ambident functionality. The successful route proceeds via hypobromous acid addition totrans-1,3,4,10a-tetrahydro-6-methoxy-4a(2H)-phenanthrenemethanamine (21) followed by a facile intramolecular cyclization to theD-norisomorphinan (23).

ISSN:0008-4042    

DOI:10.1139/v85-172

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The rates of oxidation of cinnamate ion by permanganate have been compared under conditions where distinctly different productsare obtained. Since the rates of both reactions respond in similar ways to substituent effects, deuterium substitution on the double bond, and to temperature changes, it may be concluded that the different products are due to post transition state reactions. Reaction sequences that are consistent with this conclusion and with the observed stoichiometries have been suggested.

ISSN:0008-4042    

DOI:10.1139/v85-173

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Densities and viscosities were determined for the binary systems ofm-cresol with aniline,N-methylaniline,N,N-dimethylaniline,N-ethylaniline, andN,N-diethylaniline at five different temperatures. From the experimental results, the excess volume, excess viscosity, excess molar free energy of activation of flow, excess partial molar volume, and partial molar volumes were calculated. Also various thermodynamic parameters of activation of flow were calculated from the dependence of viscosity on temperature. The deviations from ideality of thermodynamic and transport functions are explained on the basis of molecular interactions between the components of the mixture.

ISSN:0008-4042    

DOI:10.1139/v85-174

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

The dipole moments of 21 aromatic and aliphatic aldehydes were determined. Permittivity measurements were performed on highly diluted cyclohexane solutions at 20 °C. The limiting forms of Debye's, Onsager's, and Bordewijk's expressions were used. The influence of the solvent on the dipole moment values was studied using decalin and heptane mixtures. Only the Debye's values presented an apparent solvent effect while the Onsager's and Bordewijk's values remained independent of the solvent. Dipole moment values obtained using the refractive indexes of the components were also compared with those derived using the refractive indexes of the mixtures. This permitted one to estimate in 0.07 the relation between atomic and electronic polarization.

ISSN:0008-4042    

DOI:10.1139/v85-175

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

A variety of 3,3-disubstituted pent-4-enals (5a, R = Me, R′ = Et; 5b, R = Me, R′ = Ph; 5c, R = Et, R′ = Ph) has been prepared by the Raney nickel desulfurization of the corresponding 3,3-disubstituted 2,2-(trimethylenedithio)pent-4-enal precursors4a–4c. The precursor compounds were prepared by the alkylation of 2-formyl-1,3-dithiane with the appropriate 3,3-disubstituted allylic bromide. The new compounds have been characterized by elemental analysis, infrared and nmr spectroscopy, and mass spectrometry. The crystal and molecular structure of (R)-4chas also been determined by X-ray crystallography. At temperatures of ca. 130 °C, compounds4a–4cundergo intramolecular rearrangement to form the tri-substituted alkenes6a–6c, which have also been characterized by the present study.

ISSN:0008-4042    

DOI:10.1139/v85-176

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

Complex formation occurring betweenl(−)malic acid and W(VI) has been investigated by polarimetric and cryoscopic measurements, and also by proton nmr spectroscopy. The complexing ability of malic acid depends on the metal–ligand ratio. With excess W(VI), four different complexes are formed. The pH of the medium is the principal variable controlling complex formation and the various interconversion equilibria. At high pH ( > 7.0), the stable complex is a monomer, while at lower pH values dimers predominate. Conditional dissociation constants of some species have been evaluated and they show that the complexes formed with excess W(VI) have a higher stability than those found when malic acid is in excess. Comparison of the proton coupling constants shows that the conformation of malic acid in its metal complexes depends on which reagent is in excess, and leads to a number of conclusions about the structure of the dimeric species.

ISSN:0008-4042    

DOI:10.1139/v85-177

出版商:NRC Research Press    

年代:1985

数据来源: NRC

摘要:

13C–13C connectivity (INADEQUATE) experiments have been used to reassign the13C spectrum of taraxasteryl acetate. This shows that there were ten errors in an earlier13C spectral assignment for this compound. An X-ray diffraction investigation of taraxasterol shows that ring E adopts a slightly distorted boat conformation. It is suggested that severe steric interactions in the chair form force it to adopt this unusual conformation. On the basis of the1H–1H coupling constants, it is concluded that taraxasteryl acetate adopts a very similar conformation in solution. Crystals of taraxasterol–ethanol solvate are orthorhombic, space groupP21,21,21, wiha = 7.447(1) Å,b = 17.637(2) Å,c = 22.269(4) Å,U = 2925 Å3, andDcalc = 1.07 g cm−3forZ = 4.

ISSN:0008-4042    

DOI:10.1139/v85-178

出版商:NRC Research Press    

年代:1985

数据来源: NRC