The high pressure mediated intramolecular diels-alder reaction of furans: Factors controlling cycloaddition with monoactivated dienophiles

Intramolecular Diels-Alder Reactions of Tethered Enoate Substituted Furans Induced by Dialkylaluminum Chloride

Gold(I)-catalyzed cycloisomerization of enynols 11 and 17, obtained by Sonogashira coupling, led to the tethered enoate-substituted furans 14 and 19. While attempts at thermal and several Lewis acid induced intramolecular Diels-Alder reactions remained fruitless, dialkylaluminum chloride led to the formation of hexahydroindene and octahydronaphthalene derivatives 20-23. Their formation can be explained by Lewis acid induced opening of the epoxy bridge with transfer of one alkyl group to the intermediate cycloadduct.

Total synthesis of (−)-aritasone via the ultra-high pressure hetero-Diels–Alder dimerisation of (−)-pinocarvone

The total synthesis of aritasone via the proposed biosyntheic hetero-Diels–Alder [4 + 2] cyclodimerisation of pinocarvove, has been achieved under ultra-high pressure (19.9 kbar) conditions.