Total Synthesis\nof (−) and (+)-Zingibergingerols\nA

The first total synthesis of both of the enantiomers\nof Zingibergingerol\nA has been accomplished. The distinctive 3,7,9-trioxabicyclo[4.2.1]nonane\nskeleton is crafted through gold-catalyzed alkynol cycloisomerization.\nThe synthesis comprises sequential C–C bond formations at both\nends of epichlorohydrin: first opening the epoxide with eugenol-derived\nalkyne, followed by subsequent epoxide installation, and again opening\nwith a Grignard reagent. The resulting alkynol with a fixed C5 stereochemistry\nwas subjected to O-allylation, followed by dihydroxylation and alkynol\ncycloisomerization.