Synthesis of new bicycloalkane derivatives from allylic alcohols/lactols by a tandem isomerization-intramolecular aldolization process

New bicyclo[3.2.1]octanes are easily prepared in a few steps from norbornene. The key reaction in this process is the tandem isomerization- intramolecular aldol reaction from lactol 4 and/ or allylic alcohol 5, mediated by transition-metal catalysts. This reaction affords bicyclic derivative 6 as a single stereoisomer and the stereoselectivity of this process could be explained by analysis of the different transition states using high-level computational studies. The key intermediate enone 7 is easily obtained from 6 through the corresponding mesylate. The synthetic potential of bicyclic enone 7 is illustrated with several examples. © Georg Thieme Verlag Stuttgart.