摘要:

The configurations of ring nitrogen in the amine oxides of tropine, oscine, atropine, and scopolamine have been investigated by nuclear magnetic resonance (n.m.r.) spectroscopy. Oxygen function(s) at C-6β (and 7β) were found to deshield the low-field, equatorialN-methyl signal. Analysis of the n.m.r. spectra of epoxides of some tropane bases, in particular the coupling constants, clearly indicates preponderance of the (slightly distorted) chair conformation even in the tropanes with a bulky group in the 3α (endo) position. The protons on the epoxide carbons are magnetically non-equivalent in scopolamine (5b) and itsN-oxide while appearing as a singlet in the alkamine, i.e. scopine (5a).

ISSN:0008-4042    

DOI:10.1139/v68-458

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Addition of water to various solvents used for oxidative ozonolysis of oleic acid increases acid product yield and diminishes ester by-product yield but the effect is non-stoichiometric. Hydrolysis of peranhydride intermediates and chain-termination mechanisms are possible explanations. Octyl nonanoate is identified as a by-product of nonanal autoxidation; its yield is diminished by adding water or ethanol. Reduced platinum oxide catalyzes oleic acid and 5-decene ozonide autoxidation but platinum on charcoal is without significant effect.

ISSN:0008-4042    

DOI:10.1139/v68-459

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A model (not a theory), based on steric and charge removal characteristics of the substituents, is used to rationalize the low-field shifts caused by carbon tetrachloride (compared to cyclohexane) in the proton resonance spectra of 22 polyhalosubstituted benzenes. The low-field shifts are as large as 0.16 p.p.m. and these are found for protons situated between two ortho fluorine substituents. Larger halogens present a steric hindrance to the approach of the polarizable C—Cl bonds of the solvent and lead to smaller shifts. The charge removed from the region of the C—H bonds by the substituents is estimated by means of a function of the bond dipole divided by the bond length. A shape effect, arising when two hydrogens areorthoto each other, also appears to be present if there are bulky distant groups.

ISSN:0008-4042    

DOI:10.1139/v68-460

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The proton and fluorine magnetic resonance spectra of 1,3,5-trifluorobenzene oriented in a nematic liquid crystal have been analyzed. The proton and fluorine chemical shift anisotropies are −2.98 p.p.m. and 104 p.p.m. respectively. The absolute signs of the indirect spin–spin coupling constants are:JHH′,JFF, andJHF(ortho) all positive, and(para) negative.

ISSN:0008-4042    

DOI:10.1139/v68-461

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

The proton magnetic resonance spectra of 1-methylpyridinium bromide and iodide have been measured over a range of concentrations in different solvents. It is found that, with the exception of acetonitrile solutions, the infinite dilution chemical shifts are related to solvent dielectric constant. Extrapolated shifts for a nonpolar medium agree with previously calculated chemical shifts for the pyridinium ion. Proton chemical shifts in concentrated solutions are affected by cation–anion interactions. These interactions are interpreted in terms of ion pair formation.

ISSN:0008-4042    

DOI:10.1139/v68-462

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Treatment oftrans,trans-2-nitro-1,3-cyclohexanediol diacetate with ammonia followed by acetylation givestrans,trans1,3-diacetamido-2-nitrocyclohexane (4). Catalytic hydrogenation of4and subsequent acetylation lead totrans,trans-2,6-diacetamidocyclohexylamine (5) andtrans,trans-1,2,3-triacetamidocyclohexane (6), respectively. Permanganate oxidation of4affordscis-2,6-diacetamidocyclohexanone (7; 2,4-dinitrophenylhydrazone,8). Sodium borohydride reduction of7producestrans,trans-2,6-diacetamidocyclohexanol (9;O-acetate,10).

ISSN:0008-4042    

DOI:10.1139/v68-463

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Crystalline β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) has been prepared by the reaction of sulfuryl chloride withD-xylose. Anomerization of β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) yielded crystalline α-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate). Both α- and β-D-xylopyranosyl chlorides gave high yields of their inversion products on methyl glycosidation (Königs–Knorr conditions) demonstrating the non-participating properties of the chlorosulfate group. Using modified Königs–Knorr conditions β-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) was condensed with 1,2,3,4-tetra-O-acetyl-β-D-mannopyranose to give predominantly 6-O-α-D-xylopyranosyl-D-mannopyranose. A similar condensation using α-D-xylopyranosyl chloride 2,3,4-tri(chlorosulfate) did not yield the analogous 6-O-β-D-xylopyranosyl-D-mannopyranose, therefore, for comparative purposes it was synthesized by the method of Bredereck and co-workers (1).

ISSN:0008-4042    

DOI:10.1139/v68-464

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

Several steroidal pyrimidineN-oxides were synthesized by treatment of differentN-acyl derivatives of steroidal β-amino-α,β-unsaturated ketones with hydroxylamine. This procedure has been applied to obtain steroidal pyrimidineN-oxides with the heterocyclic ring condensed with rings A and B of the steroidal moiety. Some chemical and spectral properties of these derivatives are discussed.

ISSN:0008-4042    

DOI:10.1139/v68-465

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A new synthesis of α-agarofuran (1) has been realized in four steps from ketol3and a stereospecific synthesis of isodihydroagarofuran (dihydro-α-agarofuran) has been achieved in four steps.

ISSN:0008-4042    

DOI:10.1139/v68-466

出版商:NRC Research Press    

年代:1968

数据来源: NRC

摘要:

A(1,3)type strain was demonstrateddirectlyfrom the nuclear magnetic resonance studies of the acyl and nitroso derivatives of 2-methylpiperidine (2series) and 2,6-cis-dimethylpiperidine (1series). In these two series, the bulky 2-methyl groups are forced to assume the axial conformation due to a severe A(1,3)interaction in the equatorial conformation. The free energy of activation (ΔG*) for the internal rotation around the N—C and N—N bonds in1a–1gwas determined. The comparison of these (ΔG*) values with those of the corresponding derivatives of dimethylamine indicates the decreases are in the range of 3.6–4.7 kcal/mole which is in fair agreement with the conformational energy of 1,3-diaxial CH3/CH3interaction. An argument was presented to show that this interaction energy corresponds to the decrease of ΔG* in1a-1g.

ISSN:0008-4042    

DOI:10.1139/v68-467

出版商:NRC Research Press    

年代:1968

数据来源: NRC