Ortho [2+2] photocycloaddition: Application towards the total synthesis of 1-sterpurene.

摘要

Attempts to demonstrate the synthetic viability of the Wagner group's ortho [2+2] photocycloaddition and the resulting cascade of rearrangements were performed as were attempts to expand the reaction's synthetic scope. Sesquiterpene 1-Sterpurene was chosen as the synthesis target and the requisite alkene tethered acetophenone photoprecursor was derived through synthetic means. The precursors were shown to have abnormal room temperature characteristics in the 1H NMR spectroscopy. The ketone chromophores underwent hydrogen abstraction from the adjacent alkyl tether and closed to cyclobutenes fused to the arene. The ester chromophore variant does appear to undergo the desired photoaddition and rearrangements, however the material has yet to be obtained free of other similar compounds that are thought to be diastereomers/regioisomers.;Attempts to alter the product from 4,6,5 fused ring systems to simple 4,6 were approached using both temporary silicon tethers and intermolecular means. Neither route was overly successful yet however useful information towards that end has been observed in the preparation of the photoprecursor/reaction conditions.