STEREOCONTROLLED SYNTHESIS OF FUNCTIONALIZED DIQUINANES FROM PAUSON-KHAND-DERIVED EXO-TRICYCLO[5.2.1.0/2,6]DECENONES

A 10-step sequence is described for the conversion of 4-methyl-exo-tricyclo[5.2.1.0(2,6)]deca-4,8-dien-3-one (the Pauson-Khand cycloaddition product of norbornadiene with propyne) into 3,3-dimethyl-2-[(2-methoxyethoxy)methoxy]-8-(1-methyl-2-oxopropyl)bicyclo[3.3.0]octan-6-ol. The latter diquinane, formed with complete stereocontrol and well-differentiated functionality, is appropriately substituted to serve as an entry to highly functionalized linearly fused triquinanes, although attempts to close a third five-membered ring via an enolate-epoxide ring-opening process were unsuccessful.