Nine-Step Total Synthesis of (+)-Minfiensine

Significance

MacMillan and co-workers report an expedient enantioselective total synthesis of (+)-minfiensine, employing an organocatalytic cascade in the key step. Vinyl indole 2 prepared in three steps from a commercially available precursor 1 underwent an organocatalytic Diels-Alder cycloaddition with propynal, followed by isomerization and amine cyclization. In situ reduction ­furnished pyrroloindoline 4 in excellent yield and enantioselectivity. This intermediate was elaborated to (+)-minfiensine in five more steps via a radical cyclization (5 Æ 6).