SYNTHESIS OF ARISTOTELIA-TYPE ALKALOIDS .10. BIOMIMETIC TRANSFORMATION OF SYNTHETIC (+)-ARISTOTELINE INTO (-)-ALLOARISTOTELINE

Synthetic (+)-aristoteline (2) was transformed into (-)-alloaristoteline (1) in 4 steps with an overall yield of 86 %. This successful biomimetic interconversion established the Previously unknown absolute configuration of this unusual natural product which contains an inverted indole moiety. The first intermediate along this route turned out to be identical with natural (-)-serratoline (S), and a rearrangement product thereof corresponded to (+)-aristotelone (6), an alkaloid that has been isolated by others from Aristotelia chilensis in 1976. Our investigations unambiguously confirmed the tentative structure of this metabolite, which is endowed with a spiro[4.4]nonane-3-oxindole sub-unit.