A new asymmetric synthesis of the natural enantiomer of the indolizidino[8,7-b]indole alkaloid (+)-harmicine

We report a novel, facile and asymmetric approach for the synthesis of the indole alkaloid (+)-harmicine via a highly diastereoselective N-acyliminium cyclization reaction as a key synthetic step, and verify the relative stereochemistry of the key synthetic intermediate in this approach through X-ray crystallography.