Nucleophilic Substitution on 4-Methylbenzyl Thiocyanate with Nucleophiles

Article abstract of DOI:10.1246/bcsj.56.248

The reactions of 4-methylbenzyl thiocyanate (1) with several nucleophiles have been investigated.Compound 1 possesses three electrophilic sites, i.e., benzylic carbon, sulfur and cyano carbon, to receive nucleophilic attack.PhS^- and CN^- which have HOMO's of high energy levels appear to attack preferentially the sulfur atom.MeO^- was found to attack preferably the cyanide carbon, while amines which have HOMO's of low energy levels prefer benzylic carbon to attack.The nucleophilic substitution on the sulfur or the cyanide carbon generates CN^- or p-xylene-α-thiolate anion, strong nucleophiles, as the primary products, which then initiate the complex secondary reactions.The selective reactivities of three attacking sites for nucleophiles in 1 have been rationalized in terms of MO theory.