Total Synthesis of (+)‐Elacomine and (‐)‐Isoelacomine, Two Hitherto Unnamed Oxindole Alkaloids from Elaeagnus commutata.

Racemic elacomine ((±)-2), a hemiterpene spiro oxindole alkaloid from Elaeagnus commutata, was synthesized in five steps from 6-methoxytryptamine (19) in 16% overall yield (Scheme 3). The final oxidative rearrangement of the corresponding β-carboline precursor (±)-21 furnished isoelacomine ((±)-22) as a by-product (6% overall yield). A more elaborate route that started from L-tryptophan furnished (+)-2 and (−)-22 with optical purities of 76% (Scheme 4) and established the absolute configuration of these compounds. A reinvestigation of the alkaloidal content of the roots of E. commutata showed that both elacomine and isoelacomine occur naturally in racemic form.