Radical additions of acyclic and cyclic ethers to alkenes via an allyl transfer reaction involving phthalimido-N-oxyl radical

Direct functionalization of rudimentary and cheap starting materials to yield complex value added products is of great interest to synthetic chemists. Particularly, direct functionalization of cheap commodity molecules that have been traditionally considered inert to known reactions are of widespread interest. We have previously demonstrated the functionalization of benzylic C-H bonds via an allyl transfer reaction using various allyl-phthalimido-N-oxyl substrates. In this work, we demonstrate the extension of our mild, metal-free, and neutral allyl transfer methodology to the direct functionalization of ethers. The C-H bond in a position to the ether oxygen in various acyclic and cyclic ethers was functionalized in high yields demonstrating wide substrate scope for this transformation. Furthermore, selective mono-functionalization of symmetrical cyclic ethers and regioselective functionalization of unsymmetrical ethers was achieved, thus demonstrating further utility of this reaction. Finally, kinetic chain length measurements were performed, which provided valuable insights into the initial rates and efficiency of the chain process involving the phthalimido-N-oxyl (PINO center dot) radical. (C) 2016 Elsevier Ltd. All rights reserved.