The structure of roemrefine
ConclusionsStructure (1) has been established for roemrefine on the basis of a study of the products of its Hofmann degradation, oxidation, and spectral characteristics.
ON THE USE OF NUCLEAR MAGNETIC RESONANCE FOR THE DETECTION, ESTIMATION, AND CHARACTERIZATION OF N-METHYL GROUPS
A useful n.m.r. technique for the detection, estimation, and characterization of N-methyl groups is described. The method depends on the decreased shielding of Nbasic-methyl protons when the solvent is changed from deuterochloroform to perdeuteroacetic (PDA) (or acetic) acid to trifluoroacetic acid (TFA). The decreased shielding results in a downfield shift of the N-methyl resonance of ca. 0.3–1.3 p.p.m. depending on the type of amine. Most N-methyl groups on neutral nitrogen atoms show little movement. For the majority of aliphatic amines in trifluoroacetic acid the NH exchange rate is slow enough at 38° to permit observation of coupling of H(N) with the N-methyl protons, and thus determination of whether the amine is secondary or tertiary. In some cases information can be obtained about methylene and methine groups attached to basic nitrogen. In acid solution compounds with basic nitrogen attached to, or part of, an aromatic ring show considerable shift of the aromatic proton resonance signals to lower ...
Tetracyclische α-amino-indoline
Zusammenfassung Es wird die Synthese einer Verbindung (II) beschrieben, die mit dem Alkaloid C-Curarin-III (I) aus Calebassencurare in den wesentlichen Konstitutionsmerkmalen ubereinstimmt. Als Zwischenprodukte wurden tetracyclische α-Amino-indoline dargestellt, die in sauer Losung eine Ringoffnung erleiden, im alkalischen Medium aber wieder cyclisieren. Eines dieser neuen Amine, das 1,2,3,4-Tetrahydro-4a,9a-iminoathano-carbazol (XII), wurde als Echibolin bezeichnet, da es das Grundgerust des Alkaloids Echitamin darstellt.