Stemmadenia donnell-smithii

From Stemmadenia donnell-smithii, besides iboga alkaloids and voac-amine, the indole (+ )-quebrachamine (L), mp 147°—149°, [a]D +111° (CHCI3), and the indole stemmadenine (LIV, a— x or a— y bond), mp 199°-200° (dec.), [ ]D + 324° (pyridine), were isolated (11). The latter alkaloid also occurs in Diplorrhynchus condylocarpon (43) along with condylocarpine, shown (43a), to be LV (rather than LVI), and into which it was converted by potassium permanganate oxidation (44). Stem-... 

The earlier literature on quebrachamine has been dealt with in previous volumes, and its occurrence in some new sources is recorded in Table I. Most important from the biogenetic point of view is the existence in nature of both optical enantiomers. The common levorotatory form corresponds in absolute configuration to aspidospermine (II, vide infra), while the dextrorotatory form found in Stemmadenia donnell-smithii (8) is related to (+ )-pyrifolidine (XLVI, 9, 10) and to (— )-tabersonine (XCII, 7). 

Stemmadenine (CCXIII) was first isolated from Stemmadenia donnell-smithii (8), where it occurs with (+ )-quebrachamine (I) and some iboga-type bases. Subsequently, it has also been found in Diplorrhyncus condylocarpon ssp. mossambicensis, where it occurs together with condylocarpine (CCXV), normacusine-B (Section VIII, B), two yohimbines, norfluorocurarine, and mossambine (Section VI, B and C, Ref. 116). 

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