Use of cycloaddition reactions and photochemical transformations in the preparation of norcarane derivatives

We detail a strategy for the preparation of bicyclo[4.1.0]heptanes, or norcaranes, based on Diels-Alder reactions and photochemical transformations. As the latter step of the process proceeds with unique regio and stereochemistries, the regio and stereochemical outcome of the overall sequence is dictated by the structures of the diene and dienophile and the conditions used in the initial cycloaddition reaction. This allows for the preparation of norcaranes with different substitution patterns and defined relative stereochemistries, and could be exploited in the design of complex structures bearing this bicyclic moiety. (C) 2016 Elsevier Ltd. All rights reserved.