2-CYANOACRYLATES IN THE CONJUGATE ADDITION OF TRIFLUOROACETIC-ACID AND NUCLEOPHILIC-REAGENTS

In the presence of trifluoroacetic acid, ethyl 2-cyanoacrylate readily reacts with nucleophilic reagents, such as 2-chloro- 1, 3,2-berizodio xaphosphole, (Eto)3P, (EtO)2PCl, Ph2PCl, Ph3P, and thiourea. In these reactions the acid proton enters position 2 of the cyanoacrylate, wher eas the nucleophilic component enters position 3, in accordance with t he electron density distribution in the acrylate. In the absence of tr ifluoroacetic acid the above reagents, except 2-chloro-1,3,2-benzodiox aphosphole, cause ethyl 2-cyanoacrylate polymerization. The interactio n of ethyl 2-cyanoacrylate with 2-chloro-1,3,2-benzodioxaphosphole and trifluoroacetic acid is the first example of a 2-cyanoacrylate taking part in the acid-initiated electrophilic conjugate addition of a weak nucleophile.