Six-Step Total Synthesis of (±)-Conolidine

A concise total synthesis of (±)-conolidine, a potent nonopioid analgesic, in 19% overall yield is described here. A gold­(I)-catalyzed Conia-ene reaction (Toste cyclization) and a Pictet–Spengler reaction served as key transformations for assembling the 1-azabicyclo[4.2.2]­decane core and defining the geometry of the exocyclic double bond. The activation energies of formation of the vinyl-gold intermediates were calculated and revealed a silyl enol ether with an unprotected indole moiety as a suitable precursor for the Toste cyclization. This six-step synthesis did not involve any nonstrategic redox manipulations.