Venoterpine and cantleyine were chemically correlated and shown to have the same absolute configuration. Venoterpine 1' and cantleyine z2 are monoterpene alkaloids of wide natural distribution? The structure of z was proved by a chemical correlation with loganin' but the absolute configuration of 1 so far rests only a CD study4. Until now it was generally believed albeit without explanation that venoterpine 1 had the opposite configurationfromthatof cantleyine2. This situation has recently been questioned' and the simultaneous isolation in our laboratory of 1 and _2. in the same plants lead us to reexamine the situation. Compounds 1 and 2 were isolated from AZstonia angustiZoba, A.pnewnatophora and A.spatu-Zata6. Their gross structureswere established by comparison of their physical propertied_iith literaturedataTf2. Examination of their 13 C NMR spectra disclosed a similar substitution pattern for their cyclopentane ring (Table I). All these data confirmed the known relative configuration of 1 and 2, the absolute configuration of 1 only remaining to be determined-This was established by a chemical correlation between 2 and 1 based on the flash pyrolysis of the carboxylic acid derived from cantleyine. Barium hydroxide hydrolysis of z ((aID=-4@";CHCl3) followed by CO2 neutralization yielded an acid, which was dissolved in THF (2mg/ml) and submitted to vacuum flash pyrolysis in a vertical hot tube (glass beads fillinq) preheated to 460°C. Condensation of the eluate yielded tars and a single non-polar compound inall respects identical to venoterpine (MS, IR, NMR, UV, TLC). The optical rotation of this material ((a]D=+38";CHCl3) was identical to the value found for natural 1 ClalD=+32";CHC13) within experimental error. We thus conclude that 1 and 2 have the same absolute configuration as Loganin, which is probably their common genitor.