L3C-NMR data

Invention of Fourier transform instruments and consequent development of 13C-NMR techniques have supplied the chemist with excellent tools in characterizing complex molecules and making fine stereochemical distinctions. During the last two decades following the fundamental work of Wenkert (130, 228, 308), substantial amounts of l3C-NMR data of corynantheine and yohimbine alkaloids have been published. Some numerical values of interest are cited in Tables VIII, IX, X, and XI. 

Only limited reports on the NMR of other nuclides are available.136 176,180 182 258,463 Some l3C-NMR data for pyrans and thiopyrans are illustrated in Table XIX. 

H-NMR data for adducts from Reference 89, and l3C-NMR data from Reference 90. b Precursors are assigned the same letters as the corresponding ring positions of the related adducts. c InCDClj. d Reference 96. 

H- and l3C-NMR Data for ct-Adducts Formed from Naphthyridines and Amide Ion... 

H- and l3C-NMR Data of Phenyllithium-Diazine Adducts, and Some of the Corresponding Dihydro Diazines... 

As a last example, the epimerization of corynantheidol (58) is examined. Refluxing 58 in AcOH resulted in a mixture of C-3 epimers 58 and 59 in a ratio of 27 73, Fig. (14) [41]. Both compounds possess one equatorial and one axial substituent and they are in conformation a, as can be verified by l3C NMR data. The question arises as to which is the lesser evil an axial ethyl group or an axial hydroxyethyl group. The empiric result shows that the latter is preferred. A plausible explanation is that, in axial position, hydrogen bonding may exist between Nb and the alcohol proton. 

B.E. Mann and B.F. Taylor l3C NMR Data for Organometallic Compounds. Academic Press, London, New York, Toronto, Sydney, San Francisco 1981. 

When diphenylzinc was reacted with gold(III) chloride, a [Ph3ZnAu] species was obtained (117, 118). Molecular weight measurements showed this product to be dimeric, and the H-NMR spectrum indicated the presence of two types of aryl groups in a 1 2 ratio, whereas the l3C-NMR data showed these to be due to zinc-bonded and bridging aryls, respectively. Structure 3 was postulated. The same complex was obtained when Ph2Zn was reacted with [AuCl(CO)] thep-tolyl analog was also prepared. 

H- and l3C-NMR Data oi 2-. 3-. and 4-METim.-l,8-NAi>HTHYRiDiNES in Deuterochloroeorm and in Liquid Ammonia Containing Potassium Amide... 

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