Deserpine has been isolated from the roots of Rauwolfia canescens 60. Indian snakeroot ( Rauvolfia serpentina) ( Figure 9) contains reserpine and rescinnamine, the quinine tree ( Rauwolfia capra) yields quinine, and iboga milkwood ( Tabernaemontana iboga) produces iboganine. The species belonging to these genera contain L-tryptophan-derived alkaloids ( Figure 8). Don), milkwood ( Tabernaemontana L.), strophanthus ( Strophanthus DC.), voacanga ( Voacanga U.) and alstonia ( Alstonia R. Alkaloids are especially abundant in the following genera: devil's-pepper ( Rauvolfia L.), periwinkle ( Catharanthus G. The Dogbane family is a large botanical taxa containing at least 150 genera and 1700 species. This family is distributed worldwide, especially in tropical and sub-tropical areas. The Dogbane botanical family (Apocynaceae Lindl., Juss.) is a good example ( Table 2). Some plant families are especially rich in alkaloids. Ultimately, the syntheses of (−)-jerantinine A ( 23) and E ( 25) were accomplished in 29% and 23% overall yields, respectively, from (−)-tabersonine ( 21). Sequential N-Boc deprotection and selective demethylation under Waser's conditions furnished (−)-jerantinine A ( 23), which was selectively hydrogenated in the presence of PtO 2 as catalyst to yield (−)-jerantinine E ( 25). Subsequent O-methylation gave N-Boc-15,16-dimethoxytabersonine ( 563). The introduction of the C-16 hydroxyl group was achieved in a one-pot Dakin oxidation protocol by reacting 562 with a solution of H 2O 2 and a trace amount of SeO 2 followed by sodium dithionite-mediated reduction. Treatment of the resulting 15-hydroxytabersonine ( 561) with paraformaldehyde (PFA) in the presence of MgCl 2 and Et 3N afforded C-16 aldehyde 562. To install the requisite C-15 hydroxyl group, the indoline nitrogen was protected with Boc 2O, followed by a Miyaura borylation and NMO-mediated oxidation. Iodination of (−)-tabersonine ( 21) with N-iodosuccinimide (NIS) generated 15-iodotabersonine ( 559). 27 The synthesis commenced with the isolation of (−)-tabersonine ( 21) from the ground seeds of Voacanga africana with 1.4% mass recovery yield ( Scheme 67). In 2018, Moses and coworkers reported a biomimetic semisynthesis of (−)-jerantinine A ( 23) and jerantinine E ( 25) starting from (−)-tabersonine ( 21).
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