An approach to the aromadendrane carbon skeleton by a radical fragmentation/3- exo-trig cyclization sequence

Abstract

A radical fragmentation/cyclization sequence of a [2+2] photoadduct derivative leads to the formation of the aromadendrane ring system. The 5,7 fused rings of this sesquiterpenoid family are formed in the fragmentation step and the cyclopropane moiety is the result of a 3- exo-trig cyclization. The cyclization step is facilitated by the use of SmI 2 as the electron donor and by an ester group to stabilize the resultant strained intermediate.