Tetracyclic alkaloids of the sparteine group.1H and13C NMR spectroscopy and conformational analysis

Indolizidine and quinolizidine alkaloids

“…Aphylline 126 appears to have an even greater equilibrium concentration of ring C chair conformer, although the precise amount was not calculated. 88 This publication also contains reliable 1 H and 13 C chemical shift data, interpreted in terms of structural properties and substituent effects, for eleven natural and unnatural sparteine derivatives. Gradient-selected HMBC spectra have been used to elucidate the full range of 1 H- 13 C coupling constants for angustifoline 127.…”

Unusual Formation of 2-Aryl-7,7-dimethyl-6,8-epidiseleno-5,6,7,8-tetrahydro-5-quinazolones

“…Moreover, the mechanism of the latter reaction remains unthe few values of neutral diselenides reported in the literature: [10] In neutral diselenides one-bond 77 Se-77 Se coupling known. Clearly, this reaction deserves further attention.…”

“…In this context it is interesting to note that the oxidation 3 are unsymmetrical diselenides, [10] although their differences (ca. 177Ϫ184 ppm for 3a؊c) are astonishingly large.…”