The green and convergent paired Diels-Alder electro-synthetic reaction of 1,4-hydroquinone with 1,2-bis(bromomethyl)benzene

The electrochemical reduction of 1,2-bis(bromomethyl)benzene (2a) has been studied in the presence of 1,4-hydroquinone (1a) in an undivided cell in water/ethanol solution (40/60) by means of cyclic voltammetry (CV) and constant-current electrolysis. Through the paired green electro-synthesis, 1a and 2a are separately oxidized and reduced. The results revealed that the dienophile derived from the oxidation of 1a participates in two successive Diels-Alder reactions with cathodically generated o-quinodimethane (2b) to produce 5,5a,6a,7,12,12a,13a,14-octahydropentacene-6,13-dione (4b) as a final product with high yield, selectivity, purity and low waste. (C) 2014 Elsevier B.V. All rights reserved.