Electrosynthesis of heterocyclic compounds by radical cyclization in environmentally friendly media

We investigated the reductive intramolecular cyclization of bromopropargyl ethers derivatives, catalyzed by electrogenerated (1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecane)nickel(I), [Ni(tmc)]+ as the catalysts in N,N,N-trimethyl-N-(2- hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide,[N1 1 1 2(OH)][NTf2] and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C2mim][NTf2] by cyclic voltammetry and controlled-potential electrolysis. The results show that the reaction leads to the formation of the expected cyclic compounds, which are important intermediates in the synthesis of natural products with possible biological activities.

TheauthorsthankM.PassosandD.Malheirothathaveconducted part of this research. We also thank the Chemistry Department of UMIST(UK) and University of Nice (France) for the Mass Spectrometry Facility. In addition,we are grateful to the Fundação Calouste Gulbenkian and FCT (PestC/QUI/UI0686/2013 and FCOMP-01-0124FEDER-037302) for partial financial support of this work.