Synthesis and Properties of 2,3-Dialkynyl-1,4-benzoquinones



Alkynyl substituents can be used to tune the acceptor properties of benzoquinones due to their slight electron-withdrawing abilities. Applications of new acceptors rely on efficient and practical synthetic procedures. Herein we describe a general and convenient approach for the synthesis of 2,3-dialkynyl-1,4-benzoquinones using a combination of regiospecific aromatic substitution, Sonogashira cross-couplings and mild CAN oxidation chemistry. The regiochemical outcome of the synthetic protocol was verified by X-ray crystallography of two compounds. Cyclic voltammetry, UV/Vis and DFT calculations on three derivatives show that the symmetrical dialkynyl-substituted benzoquinones are attractive acceptors.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)