Azo Group-Assisted Nucleophilic Aromatic Substitutions in Haloarene Derivatives:  Preparation of Substituted 1-Iodo-2,6-bispropylthiobenzenes

Aryldiazo substituents were used in nucleophilic aromatic substitution reactions of halogens. The Ph-NN− group activates ortho fluorine atoms toward alkylthiolation under mild conditions. In contrast, the Me₂N-C₆H₄-NN− group has virtually no activation effect in nucleophilic aromatic substitution, and serves as a “neutral” mask for the amino group. The Ph-NN− group was efficiently introduced by diazo coupling of aryllithium with dry PhN₂⁺BF₄^- salt.