Total Synthesis of (−)‐Kopsinine by an Asymmetric One‐Pot [N+2+3] Cyclization

All together now: A common intermediate of Kopsia alkaloids was synthesized from cis-2,3-disubstituted piperidine, which was obtained with 98 % ee in 85 % yield using chiral diether-controlled asymmetric conjugate addition of lithium amide to indolepropenoate, followed by C,N dual alkylation with 1-chloro-3-iodopropane. The synthesis of (−)-kopsinine was accomplished via the intermediate in 9.0 % overall yield in 13 steps.