The [4+4] photocycloaddition of a 2-pyridone, forms a �cage-like� photodimer, a tricyclic cyclooctadiene structure.   In a one step reaction, not only is the highly sought after 8-membered ring realized, but also, the formation of four asymmetric centers with functionality at each center.  The reaction is regioselective for the head-to-tail addition along with being stereoselective for the trans product.    This photodimer is achiral, however, due to its centrosymmetric structure.   Electrophilic addition to one double bond results in a nitrogen migration destroying the symmetry to give a chiral product with six contiguous stereogenic centers.  Subsequent cleavage of the lone double bound and the bridging lactams will lead to an acyclic compound with predicted stereochemistry.  In this poster, we present the results and challenges of the above synthetic strategy to yield a stereo-defined acyclic compound from readily available achiral starting materials.

Desymmetrization of the centrosymmetric 2-pyridone photodimer

244th National Meeting (2012)

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