Enantio- and Stereoselective Construction of Atisane Scaffold via Organocatalytic Intramolecular Michael Reaction and Diels–Alder Reaction

An enantio- and stereoselective
construction of the atisane scaffold
via organocatalytic intramolecular Michael reaction and Diels–Alder
reaction is described. The organocatalytic intramolecular Michael
reaction has been found to stereoselectively generate a trans-stereodiad comprising an all-carbon quaternary and a tertiary stereogenic
centers. Use of the chiral secondary amine bearing thiourea with benzoic
acid as additive is the key to obtaining the desired product with
excellent ee in synthetically acceptable yield. The prepared chiral
building block has been successfully converted to the compound including
the atisane scaffold via the highly stereoselective intramolecular
Diels–Alder reaction.