Serial Radical Cyclization of Pyranose-Derived Dienes in the Stereocontrolled Synthesis of Densely Functionalized Cyclohexanes. A Route to Woodward's Reserpine Precursor
摘要:
Serial radical 5-exo/6-exo cyclizations of a readily prepared hexopyranose derivative having unsaturations on-template at C-2 and off-template at C-7 lead to a tricyclic cage in which all but one of the stereocenters in an optically pure form of Woodward's densely functionalized carbocyclic precursor have been established, the ''one'' requiring an hydroxyl epimerization.