摘要:

AbstractTautomerism of aromatic β‐ketoaldehydesp‐XPhCOCH2CHO (1, X = NMe2, OMe, Me, H, Br, NO2), aliphatic β‐ketoaldehydes and benzoylacetaldehyde RCOCH2CHO (2, R = Me,i‐Bu,t‐Bu, Ph), RCOCH(Me)CHO (3, R = Me, Et,i‐Pr) and methyl 2‐formylpropionate MeOCOCH(Me)CHO (4) has been studied by the1H NMR technique. In basic solvents bothcis‐ andtrans‐enol forms of these compounds co‐exist.trans‐Enolisation, which occurs exclusively at the formyl group, is most favoured in compound (4) and least favoured in compounds (1) and (2). The increasing electron‐attracting property of the substituent X in the aromatic β‐ketoaldehydes (1), as well as increasing solvent basicity in the series propanediol‐1, 2‐carbonate, acetone

ISSN:0030-4921    

DOI:10.1002/mrc.1270070302

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractLa mesure des spectres de résonance magnétique nucléaire de13C de plusieurs alcoylcobaloximes RCo(DMG)2B (DMG = anion diméthylglyoximate, B = amine) a permis de déterminer les effets α, β et γ du groupement Co(DMG)2B sur les déplacements chimiques des carbones du radical alcoyle R. Les déplacements chimiques des carbones des ligands diméthylglyoximates et de l'amine B sont peu dépendants de la nature du radical R. Les valeurs de δ C paradans les benzylcobaloximes XC6H4CH2Co(DMG)2B sont en accord avec un effet donneur du radical CH2Co(DMG)2B. Les constantes de couplages1J(13CH) mesurées dans les méthylcobaloximes enrichies en13C sur le méthyle ont une valeur constante lorsque B varie (J13CH = 137 ± 1 Hz) et voisine de celle trouv

ISSN:0030-4921    

DOI:10.1002/mrc.1270070303

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractThe carbon‐13 spectra of seventeen bicyclo[3.1.1]‐heptane derivatives have been recorded and assigned. Study of the C‐6 and C‐7 chemical shifts permits the conformations to be assigned to the bridged chair, Y‐shaped, or bridged boat conformations. The spectrum of verbenone is anomalous and is compared to that of umbellulone recorde

ISSN:0030-4921    

DOI:10.1002/mrc.1270070304

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractDie13C‐NMR‐chemischen Verschiebungen von Uronium‐, Thiouronium‐ und Guanidiniumsalzen werden mit den entsprechenden ungeladenen Harnstoffen, Thioharnstoffen und Guanidinen verglichen. Die chemischen Verschiebungen der aromatischen Kohlenstoffatome geben in Zusammenhang mit den entsprechenden Phenolen und Thiophenolen einen Einblick in die Ladungsverteilung in diesen S

ISSN:0030-4921    

DOI:10.1002/mrc.1270070305

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractThe13C NMR spectra of fusicoccin, some of its cometabolites and derivatives were studied. Using standard Fourier transform techniques,T1relaxation time measurements and lanthanide shift reagents, the resonances of individual carbon‐13 nuclei were assigne

ISSN:0030-4921    

DOI:10.1002/mrc.1270070306

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

摘要:

AbstractThe temperature dependent spectra of several mono‐, di‐ and trialkylthioureas have been recorded. Free energy barriers to internal rotation about the CN bonds have been calculated. In thioureas that were unsymmetrically substituted, free energy barriers were found to be different for each CN bond with the more substituted amino group exhibiting the higher barrier. The monosubstituted thioureas showed different rotational barriers for the NH2groups of thecisandtransisomers, respectively. The free energy barriers for thetransisomers were found to be substituent dependent and substantiate the reassignment of the high and low field substituent signals to thetransandcisisomers, respectively. The spectrum of 1‐methyl‐3‐t‐butylthiourea indicates restricted rotation of thet‐butyl group at tempera

ISSN:0030-4921    

DOI:10.1002/mrc.1270070307

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY

ISSN:0030-4921    

DOI:10.1002/mrc.1270070301

出版商:John Wiley&Sons Limited    

年代:1975

数据来源: WILEY