Synthesis and structure of (+)-2-thionosparteine, a new thioanalogue of lupanine

(+)-2-Thionosparteine was obtained for the first time. H-1 and C-13 NMR spe ctroscopy were used for quantitative determination of conformational equili brium in solution. The X-ray structure revealed two molecules in the asymme tric unit that differ substantially in their conformations, Weak C-H ... S interactions are characterized and compared with the intramolecular hydroge n bond C-H ... O in the crystal structure of 2-oxosparteine. (C) 1998 Elsev ier Science B.V. All rights reserved.