Note on the esterification of someZ-amino acids with glyceraldehyde-diethylacetal

The selective esterification of someZ-amino acids with glyceraldehyde-diethylacetal by using different OH-blocking groups is described.     

Malzoxazin,eine tricyclische Verbindung aus Gerstenmalz

Maltoxazine, a Tricyclic Compound from Malt A new tricyclic compound, named maltoxazine, has been isolated from malt as well as from the reaction products formed in a model reaction of maltose with proline. The structure of maltoxazine ( 1 ) has been established by ¹H- and ¹³C-NMR. spectroscopy. The formation of 1 in several model reactions is strongly correlated with the formation of maltol and 5-hydroxy-5,6-dihydromaltol.     

Zur Anwendung von NMR-Verschiebungsreagenzien: Die Komplexbildungskonstante als Strukturparameter

The determination of the structure of a tetra-tert-butylfluoren-9-ol, using the complex formation constants of some known tert-butylfluorenols with Eu(fod)₃, is described.     

Dynamic 13C NMR studies on the internal rotation in tetraarylallyl anions

Proton noise decoupled ¹³C NMR spectra of lithium 1,1,3,3-bis (2,2′-biphenylylene)propenide and lithium 1,1,3,3-tetraphenylpropenide have been studied, and complete assignments have been made based on several methods, e.g. ¹³C? ¹³C coupling constants of selectively labelled compounds and low-temperature splitting of temperature dependent signals. The barriers to rotation about the partial double bonds of the allyl group have been determined by ¹³C DNMR resulting in the thermodynamic parameters of activation ΔG = 57 kj mol^?1, ΔH^≠ = 56.5 kj mol^?1, ΔS^≠ = ?3J mol^?1K^?1 and ΔG = 55.5 kj mol^?1, ΔH^≠ = 63 kj mol^?1, ΔS^≠ = 26 kJ mol^?1K^?1, respectively. The results are discussed, including the hitherto known data about the topomerisation process.