E)-Selective oxygenation of 1,2-disubstituted alkenylcyclopropanes, and subsequent SmI* mediated cleavage of the 1,2-dioxolane products with retention of stereochemistry, leads to a concise synthesis of the plant metabolite (f)-yashabushitriol.
The ready availability of substituted, stereochemically defined 1,2-dioxolane rings via the chalcogen radical catalyzed combination of O2 with functionalized vinylcyclopropanes may provide access to a wide range of 13-dial target structures.
Our original efforts in this area documented high levels of stereoselectivity upon formation of the 1,Zdioxolane moiety.' However, secondary stereochemical issues, such as the selectivity of alkene formation (E vs Z) upon oxygenation of 1,2-disubstituted alkenylcyclopropanes (Eq, l), or the maintenance of stereochemical integrity upon reductive cleavage of the dioxolane ring to afford the 1,3-diol target (2-3), have not yet been addressed. Herein, we report our preliminary investigations in these areas, and document high levels of stereoselectivity for both issues. The utility of this chemistry in natural product synthesis is further illustrated by application of a (E)-alkenyl-1,2-dioxolane species in the concise total synthesis of (f)-yashabushitriol (24).2