摘要:

AbstractCreatine (N‐methyl‐N‐amidinoglycine), creatinine (1‐methyl‐2‐aminoimidazolin‐4‐one) and a series of 38 of their close structural analogs have been examined using natural abundance13C NMR spectroscopy at 25.16 MHz. Both proton‐coupled and proton noise‐decoupled spectra were recorded. Unequivocal assignments of the carbon resonances could be made in the vast majority of cases. Both13C NMR chemical shifts and1J(CH) values can be used to characterize and to differentiate readily between analogs of creatine and analogs of creatinine. For example, the1J(CH) coupling constants for the α‐carbons of the acyclic creatine analogs were all in the 140–142 Hz range, whereas the corresponding coupling constants for the related, cyclized creatinine analogs were all

ISSN:0030-4921    

DOI:10.1002/mrc.1270130202

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractAnalysis of the13C NMR spectra of a series of 2,3‐dihydro‐1H‐pyrrolo[1,2‐c]imidazole derivatives has provided chemical shift data for (˜184 ppm), (˜173.5 ppm), (˜158 ppm) and (˜148 ppm) groups. A full analysis of the13C chemical shifts of the C atoms of the pyrrole ring and of anN‐phenyl substituent

ISSN:0030-4921    

DOI:10.1002/mrc.1270130203

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractAn earlier paper by the authors has undergone criticism by Jankowski and Rabczenko. The arguments presented are analysed in this paper and the criticism is rejected.

ISSN:0030-4921    

DOI:10.1002/mrc.1270130204

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractCarbon‐13 chemical shifts of fourteenpara‐substituted benzylbenzenes have been determined. The relative substituent chemical shifts (SCS) of the methylene carbons and the aromatic ring carbons (C‐4, C‐1′ and C‐4′) correlated well with the Hammett substituent effects using the dual substituent parameter method. The transmission of substituent effects through the benzylbenzene system is brie

ISSN:0030-4921    

DOI:10.1002/mrc.1270130205

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractSpearman's rank correlation method is suggested as an alternative procedure for the treatment of lanthanide induced shift data. When this method is applied to Sullivan's data [J. Am. Chem. Soc.98, 7162 (1976)], the results are similar to those obtained by the jack‐knife and Kendall techniques, which were introduced in a previous article. All three methods are able to distinguish between closely related structures. Among these three non‐parametric methods, the Spearman procedure is probably the simpl

ISSN:0030-4921    

DOI:10.1002/mrc.1270130206

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractThe assignment of the (C, H) couplings inN‐acetylimidazole and the determination of the relative signs of all (C, H) and (H, H) couplings with SPI experiments are described. All coupling constants are of the same, positive, sign as the directly‐bonded (C, H) coupling constants. Some advantageous features of the SPI technique, such as selectivity and increased sensitivity, are discussed in comparison to conventional double irradiation meth

ISSN:0030-4921    

DOI:10.1002/mrc.1270130207

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractChemical shifts and substituent chemical shift (SCS) effects are reported for 21 monosubstituted iso‐quinolines, carrying a halogeno, amino, piperidino or ethoxy group in position 1, 3 or 4. In some cases, assignments of13C resonances were based on the spectra of the corresponding 5‐deutero derivatives. For the fluoroisoquinolines some13CF coupling constants are given. The13C NMR spectra of 15 disubstituted isoquinolines were measured; with a few exceptions, mainly the 3,4‐ and 1,4‐disubstituted isoquinolines, the chemical shifts agreed well with those calculated by addition of the SCS

ISSN:0030-4921    

DOI:10.1002/mrc.1270130208

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractOne methyldecahydroisoquinoline and some octahydro‐ and decahydro‐isoquinolone derivatives were studied by13C NMR. The configuration of these products was deduced by comparison of the experimental chemical shifts and the calculated values. Conclusions could thus be reached on the configuration of related 8,13‐diazasteroids in the 19‐norandrostane

ISSN:0030-4921    

DOI:10.1002/mrc.1270130209

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractCarbon‐13 chemical shift assignments have been obtained for the naturally occurringCephalotaxusalkaloids, cephalotaxine, acetylcephalotaxine, harringtonine, isoharringtonine, drupacine and cephalotaxinon

ISSN:0030-4921    

DOI:10.1002/mrc.1270130210

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractCalculations of the dependence of13C chemical shifts on the dielectric constant, ϵ, of the medium are reported using the INDO/S parameterized version of Pople's method together with the solvaton model. Satisfactory agreement with the available experimental data is obtained. The rather sensitive dependence of chemical shift upon ϵ suggests that polar solute—solvent interactions in aprotic media should be taken into account when considering13C chemical shi

ISSN:0030-4921    

DOI:10.1002/mrc.1270130211

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY