Highly efficient and eco-friendly gold-catalyzed synthesis of homoallylic ketones

We report a new catalytic protocol for the synthesis of γ,δ-unsaturated carbonyl units from simple starting materials, allylic alcohols and alkynes, via a hydroxalkoxylation/Claisen rearrangement sequence. This new process is more efficient (higher TON and TOF) and more eco-friendly (increased mass efficiency) than the previous state-of-the-art technique. In addition, this method tolerates both terminal and internal alkynes. Moreover, computational studies have been carried out in order to shed light on how the Claisen rearrangement is initiatedThe ERC (Advanced Investigator Award-FUNCAT), EPSRC and Syngenta are gratefully acknowledged for support. Umicore AG is acknowledged for their generous gift of materials. The EPSRC National Mass Spectrometry Service Centre (NMSSC) is gratefully acknowledged for HRMS analyses. S.P.N. is a Royal Society Wolfson Research Merit Award holder. S.P.N. and L.C. thank King Abdullah University of Science and Technology (CCF project) for support. L.C. thanks the HPC team of Enea for using the ENEA-GRID and the HPC facilities CRESCO in Portici (Italy) for access to remarkable computational resources. A.P. thanks the Spanish MINECO for a Ramon y Cajal contract (RYC-2009-05226) and European Commission for a Career Integration Grant (CIG09-GA-2011-293900