Stereoselective trimerization of [(S)R]-[(p-tolylsulfinyl)methyl]-p-quinols and p-quinamines

reaction: see text] The asymmetric synthesis of pentacyclic derivatives was achieved in a single step starting from enantiopure (S)R]-(p-tolylsulfinyl)methyl]-p-quinols or the nitrogen analogue, through a domino sequence involving four conjugate additions in excellent yields. Eight new stereogenic centers were created in one step and in a highly diastereoselective manner.