Alkaloids of the Leaves of Erythroxylum Hypericifolium

Chiral Resolution and Absolute Configuration of 3α,6β-Dicinnamoyloxytropane and 3α,6β-Di(1-ethyl-1H-pyrrol-2-ylcarbonyloxy)tropane, Constituents of Erythroxylum Species

“…Structural characterization was made by one-and two-dimensional NMR measurements. In the case of 1, complete assignment of the 1 H and 13 C NMR spectra (Table 1) was necessary since only EIMS data were available [3]. In the case of 2, the NMR data were in agreement with previously reported values [2].…”

“…Tropane alkaloids isolated from Erythroxylum species show optical isomerism arising from different substitution patterns at the molecular scaffold. In the cases of 3α,6β-dicinnamoyloxytropane (1), from E. hypericifolium [3], and of 3α,6β-di(1-methyl-1Hpyrrol-2-ylcarbonyloxy)tropane or catuabine E (2), from E. vacciniifolium [2], this stereoisomerism can be related to other esters derived from the natural (+)-(3R,6R)-or (-)-(3S,6S)-3α,6βtropanediol enantiomers (3) for which, in most cases, no absolute configuration (AC) has been established [4][5][6]. The lack of stereochemical information seems to be due to the amounts of sample needed for the hydrolysis reaction to correlate chemically these esters with tropanediols of known AC [7], like 2 reported with  D = -35.4, for which no AC is proposed up to now [2], and for natural occurring 1 for which no optical activity data are available [3].…”