Green and efficient one-pot Diels-Alder electro-organic cyclization reaction of 1,2-bis(bromomethyl)benzene with naphthoquinone derivatives

• The proposed methodology could be an attractive and useful tool in synthetic chemistry for the preparation of natural products using electrochemical methods.
• This reaction proceeds in a single step by an environmentally friendly reagent-less method in aqueous solution with high atom economy at ambient conditions.
• The Diels-Alder reaction can be performed under very mild conditions in the absence of any acid, base or metal catalyst.

The electrochemical reduction of 1,2-bis(bromomethyl)benzene (1a) has been investigated in the presence of naphthoquinone derivatives (2a-c) in EtOH/LiClO4 solution using cyclic voltammetry (CV) and constant-current electrolysis. The voltammetric results indicate that an electro-reductive Diels-Alder type sequential reaction occurs between 2a-c and cathodically generated o-quinodimethane (1b) to produce 3a-c as final products. The mechanism of the electrochemical reaction is proved as an electron transfer-chemical reaction (EC) pathway using the constant–current electrolysis

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