Aziridinomitosenes by Anionic Cyclization: Deuterium as a Removable Blocking Group

Treatment of 11a with methyllithium affords the destannylated product 12 together with a small amount of tetracyclic product derived from intramolecular Michael addition. The same procedure from the deuterated analogue 11b gives the tetracyclic 18 as the major product, the result of a substantial kinetic deuterium isotope effect that favors formation of 16 and 17 by suppressing indole ring lithiation to the undesired 15. When the product mixture is quenched with phenylselenenyl chloride, 17 is converted into the aziridinomitosene 19 in 80% yield. Conversion into the aziridinomitosene alcohol 21 and the deprotected aziridine 20 is also demonstrated.