Trimethylsilylcyanation of heterocyclic imines catalysed by Lewis acids

The addition of Me₃SiCN to Schiff bases 1a–8a, synthesized by the reaction of furan and thiophene aldehydes with 3‐ and 4‐aminobenzotrifluorides, has been studied in the presence of various Lewis acids. A series of the corresponding trifluoromethyl derivatives of heterocyclic α‐aminonitriles 1–8 was synthesized in 38–80% isolated yields. It was found that 4A molecular sieves (MS) accelerate the addition and increase the yields of the products. The investigated catalysts are ranked by their activity in the following order: AlBr₃ + 4AMS > AlBr₃ > AlCl₃ > TiO(iPr)]₄. A single crystal of N‐(5‐methyl‐2‐thienylcyanomethyl)‐3‐trifluoromethylaniline was obtained and studied by X‐ray diffraction. The results showed that it was the crystal of the (R) isomer of this compound. Copyright © 2000 John Wiley & Sons, Ltd.