摘要:

AbstractThe conformational preference of the thymine base ring with respect to the sugar ring in β,β,β,‐trichloroethyl 5′amino‐5′‐deoxythymidine‐5′‐phosphate has been studied by13C n.m.r. spectroscopy. The magnitude of the three bond vicinal coupling constant,J(C‐2, H‐1′), for β,β,β‐trichloroethyl 5′‐amino‐5′‐deoxythymidine‐5′‐phosphate and the similarity between the chemical shifts for the furanose carbons C‐1′, C‐2′, and C‐3′ in β,β,β‐trichloroethyl 5‐′‐amino‐5′‐deoxythymidine‐5′‐phosphate and in β,β,β‐trichloroethyl thymidine 5′‐phosphate indicate that the amino analogue exists in aqueo

ISSN:0030-4921    

DOI:10.1002/mrc.1270090902

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

Abstract13C chemical shifts and coupling constants of phosphoserine in aqueous solutions were studied as a function of pH values. Carboxyl and α‐amino titration shifts agree with those observed in amino acids. The analysis of the coupling constants indicates that for rotation about the (C)CO(P) axis thetransconformer predominates for all pH values. The fractional population of thegaucheconformer reaches a maximum

ISSN:0030-4921    

DOI:10.1002/mrc.1270090903

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractL'étude en RMN du13C de neuf azapentalènes a été effectuée. Tous les signaux ont été attribués. Dans un cas on a mis en évidence des couplages entre les atomes de carbone et l'hydrogène porté par l'azote pyrrolique, fait exceptionnel dans le cas des hétérocycles aromatiques polyazotés. On démontre l'utilité de la RMN du13C pour l'étude de la taut

ISSN:0030-4921    

DOI:10.1002/mrc.1270090904

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractOn décrit les spectres de RMN du13C de diverses halogéno bicyclo[3.2.1]octanone‐3 et diméthyl‐7,7 bicyclo[3.1.1]heptanone‐3. S'il s'avère impossible de faire des corrélations systématiques au niveau des effets β, il est par contre possible de relier semi‐quantitativement les effets α et γ aux facteurs géométriques. La RMN du13C permet ainsi d'appréhender les effets ré

ISSN:0030-4921    

DOI:10.1002/mrc.1270090905

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractQuantitative analysis by n.m.r. using precision coaxial tubing is described. A solution of the intensity standard is placed in the central capillary and the sample of interest in the surrounding annulus. By this method the contamination of the sample by the standard compound can be avoided and an accurate determination can be carried out by using solutions of correct concentrations of the intensity standard. Applications to several types of quantitative problems are given. In order to get a higher accuracy and precision the experimental conditions were also studied.

ISSN:0030-4921    

DOI:10.1002/mrc.1270090906

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractLe diméthylsulfoxyde (DMSO) est utilisé comme solvant pour étudier l'acidité cinétique de très faibles diacides organiques par RMN du proton. Un examen du spectre de l'alcool propargylique en fonction du pHmet en évidence less mécanismes de transfer su

ISSN:0030-4921    

DOI:10.1002/mrc.1270090907

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractThe13C n.m.r. data of a variety of 4eq‐ and 4ax‐substituted adamantanones and bicyclo[2.2.2]octanones are presented. It is shown that for a number of carbons the chemical shifts cannot be predicted by a given additivity rule. The deviations of the observed chemical shifts from the calculated ones are discussed in terms of different interaction mechanisms operating through the σ bond frameworks or through s

ISSN:0030-4921    

DOI:10.1002/mrc.1270090908

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractThe13C chemical shifts for 1,3‐dithiane and 9 methyl substituted derivatives are reported. Only three of the methyl‐1,3‐dithianes were conformationally anancomeric and hence the conformational equilibria must be taken into account when deriving the values of the different substituent effects on the13C chemical shifts. The best fit for each substituent effect was obtained when –ΔGθ(5a‐Me) for 5‐methyl‐1,3‐dithiane was given the value 3.8 ± 0.3 kJ mol−1and when the difference between –ΔGθ(2a‐Me) and –ΔGθ(5a‐Me) forcis‐2,5‐dimethyl 1,3‐dithiane equalled 3.4 ± 0.4 kJ mol−1. The conformer populations chosen from our earlier paper1were then suitable for all the other conformational equilibria in question. The magnitude of the derived substituent effects are compared w

ISSN:0030-4921    

DOI:10.1002/mrc.1270090909

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractCarbon‐13 and proton nuclear magnetic resonance (n.m.r.) spectra of ten chlorinated hydrocarbons, which are components of technical chlordane and one chlordane metabolite, were examined. For chlordene, dichlorochlordene,cis‐ andtrans‐nonachlor, andcis‐ andtrans‐chlordane, whose chemical structures are well‐established, the relationships between the n.m.r. parameters and these structures were investigated. The results allow confirmation of proposed structures for α‐, β‐, and γ‐chlordene. A structure, corresponding to 2,4,5,5,6,7,8,8‐octachloro‐2,3,3a,4,5,7a‐hexahydro‐1,4‐methano‐1‐H‐indene, is proposed for another chlordane component,

ISSN:0030-4921    

DOI:10.1002/mrc.1270090910

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY

摘要:

AbstractThe13C n.m.r. spectra of complexes betweeno‐chloranil and aromatic electron donors were studied. Complexation leads to a general diamagnetic shift of the13C n.m.r. signals for the acceptor (o‐chloranil), but for signals from the13C nuclei in the donors both diamagnetic and paramagnetic shifts are found.These phenomena are thought to be the result of competing anisotropy and charge‐migration effects. Charge migration ino‐chloranil complexes appears to be more important than in corresponding 1,3,5‐trinitrobenzene

ISSN:0030-4921    

DOI:10.1002/mrc.1270090911

出版商:John Wiley&Sons Limited    

年代:1977

数据来源: WILEY