Enantioselective Alkoxycyclization of 1,6‐Enynes with Gold(I)‐Cavitands: Total Synthesis of Mafaicheenamine C

Chiral gold(I)‐cavitand complexes have been developed for the enantioselective alkoxycyclization of 1,6‐enynes. This enantioselective cyclization has been applied for the first total synthesis of carbazole alkaloid (+)‐mafaicheenamine C and its enantiomer, establishing its configuration as R. The cavity effect was also evaluated in the cycloisomerization of dienynes. A combination of experiments and theoretical studies demonstrates that the cavity of the gold(I) complexes forces the enynes to adopt constrained conformations, which results in the high observed regio‐ and stereoselectivities.