Organocatalyzed Selective C-D/C-H Exchange Reactions in Conjugated Triene

The reaction of N-(2,4-dinitrophenyl)pyridinium-d5 chloride with N-(4-methylphenyl)piperazine in refluxing ethanol led to the ring opening of the pyridinium-d5 ring to afford the conjugated triene with a penta-2,4- dienylideneammonium-d5 (PDA-d5) group, namely, triene-Da2Db2Dc. The reaction of triene-Da2Db2Dc with 1,1,2,2- tetracyanoethylene (TCNE) or 7,7,8,8-tetracyanoquinodimethane (TCNQ) in methanol (MeOH) and N,N-dimethylformamide (DMF) selectively activated the C-D bonds at the 2- and 4-positions of the PDA-d5 group. The present selective C-D/C-H exchange reaction may have applications in the development of new organocatalyzed coupling reactions