Tricyanomethane or Dicyanoketenimine-Silylation makes the Difference.

Pseudohalides such as tricyanomethanide, [C(CN)], are well known in chemistry, biochemistry and industrial chemistry. The protonated species HC(CN), a classic hydrogen pseudohalide Brønsted acid, is a very strong acid with a pK value of -5. However, HC(CN) is difficult to handle as it tends to decompose rapidly or, more precisely, to oligo- and polymerize.

A Lewis Acid Stabilized Ketenimine in an Unusual Variant of the Electrophilic Aromatic Substitution.

Electrophilic aromatic substitution (EAS) can provide a straightforward approach to the efficient synthesis of functionalized complex aromatic molecules. In general, Lewis acids serve as a beneficial stimulus for the formation of a Wheland complex, the intermediate in the classical S Ar mechanism of EAS, which is responsible for H/E (E=electrophile) substitution under formal H elimination. Herein, we report an unusual variant of EAS, in which a complex molecule such as the tricyanomethane, HC(CN) , is activated with a strong Lewis acid (B(C F ) ) to the point where it can finally be used in an EAS.