A SIMPLE APPROACH TO THE BICYCLO[5.3.1]UNDECANE SYSTEM PRESENT IN TAXANES

A simple route for the synthesis of the bicyclo[5.3.1]undecane ring system present in taxanes has been developed. The key steps involve the cleavage of a carbon-carbon bond in the tricyclo[5.2.1.0(2.6)]decane system 5 and a one-carbon ring enlargement of the latter to the bicyclo[5.3.1 ] undecane system 23. The potential generality of this ring cleavage process has been examined using various tricyclo[5.2.1.0(2.6)]decane derivatives 5, 10 and 13 which have been prepared either through a [4 + 2] cycloaddition reaction or by annelation via alkylation of the vicinal dianion. The scope and limitations of both these routes to the synthesis of the tricyclo[5.2.1.0(2.6)]decane derivatives have been demonstrated.