Gloria G. Lyle

The configurations at C-9 of the cinchona alkaloids : NMR spectral study of the derived oxiranes

Abstract The existing ambiguity regarding the configurations of quinine, quanidine, cinchonine, cinchonidine, and their C-9 epimers has been resolved by stereospecifically converting quaternary salts of the dihydro derivatives of quinine, quinidine, quinidine-9d, and epiquinidine to derivatives containing the conformationally rigid oxirane ring. The configurations of the oxiranes were determined by NMR spectroscopy, and the stereochemistry of the alkaloid percursors was deduced on the basis of the known stereochemical course of the reactions used in the preparation of the oxiranes. In this way, it has unequivocally been demonstrated that the natural cinchona alkaloids are all of the erythro configuration with respect to their C-8, C-9 systems and that the epi-bases are threo.

Structure of a dimeric piperidone-aldehyde condensation product

Abstract The base-catalyzed condensation of benzaldehyde with 1-methyl-4-piperidone (5) gave two isomeric products which were dimers of 3-benzylidene-1-methyl-4-piperidone (7). Reactions of the dimers and their mass spectral data are examined on the basis of the X-ray structural analysis of the dibromo derivative of the dimer which was identified as 4-p-bromobenzylidene-9-p-bromophenyl-10a-hydroxy-2,7-dimethyl-2,7-diaza-10-oxa-1,2,3,4,5,6,7,8,8a,10a,-decahydroanthracene (10b).

Rotatory dispersion studies—V : The cinchona alkaloids

Abstract The ORD curves of some alkaloids of the cinchona family and their 9-chloro-9-deoxy, 9-deoxy-, 9-oxo-, 8,9-anhydro-, 9-epi- and apo-derivatives have been examined. Most of the Cotton effects could be ascribed to the optical anisotropy of the quinoline ring or some more complex chromophore such as the carbonyl group conjugated with the aromatic ring as in 9-oxo-derivatives. The CD curves of three of these compounds confirmed the Cotton effects at long wavelength resulting from the anisotropy of the aromatic quinoline ring. The mutarotation of the 9-oxo-derivatives has been studied by ORD.

Rotatory dispersion studies III. The cinchona alkaloids

Abstract The ORD curves of some alkaloids of the cinchona family and their 9-chloro-9-deoxy, 9-deoxy-, 9-oxo-, 8,9-anhydro-, 9-epi- and apo-derivatives have been examined. Most of the Cotton effects could be ascribed to the optical anisotropy of the quinoline ring or some more complex chromophore such as the carbonyl group conjugated with the aromatic ring as in 9-oxo-derivatives. The CD curves of three of these compounds confirmed the Cotton effects at long wavelength resulting from the anisotropy of the aromatic quinoline ring. The mutarotation of the 9-oxo-derivatives has been studied by ORD.