Alstolactines A-C, novel monoterpenoid indole alkaloids from Alstonia scholaris

Three novel ring-fused monoterpenoid indole alkaloids, alstolactines A-C (1-3), were isolated from the long-term stored leaves of Alstonia scholaris. Their structures were identified on the basis of extensive spectroscopic data and X-ray diffractions. Moreover, the absolute configurations of these related structures were indicated by the crystal X-ray diffractions (Mo Kα) of 1a, a chlorinated derivative of 1.