The pentacyclic compound 7a, possessing the C20 gibberellin skeleton,
is Obtained via a 10-steP synthetic sequence from 3-ethoxy-2-cyclohexe
n-1-one (2); the most interesting steps of the overall conversion invo
lve Pd2+-promoted cyclization of the silyl enol ether of 3, and stereo
selective intramolecular Diels-Alder reaction of the substrate 6.