A Three-Step Enantioselective Synthesis Of (+)- And (-)-Alpha-Thujone

The stereocontrotted three-step synthesis of either enantiomer of alpha-thujone from commercially available 3-methyl-1-butyne is described. The enantiosetectivity originates from a Brown crotylation which is then conferred to the all-carbon quaternary center via chiratity transfer in a gold-catalyzed cycloisomerization. The route is highly atom economical and requires no protecting groups or redox manipulations.