Aza-Claisen rearrangement as a key step in synthesis of specialised anilines used in the production of efficient ethenolysis catalysts

Abstract

The employment of aza-Claisen rearrangement and subsequent reduction of the resulting anilines proved to be an efficient method for the synthesis of inexpensive 2-isopropyl-6-methylaniline analogues, thus removing the bottleneck associated with the high price and low availability of the latter. The obtained aniline derivatives were used in the synthesis of a series of lipophilic Hoveyda–Grubbs-type complexes with CAAC ligands, catalysts particularly efficient in ethenolysis reactions. The best members of this family with bulky sec-butyl substituent used in 3 ppm loading and in the presence of ethylene 3.5 are superior to the leading catalyst based on 2-isopropyl-6-methylaniline in the ethenolysis of methyl oleate, achieving a TON of up to 192 000, which makes them valuable candidates for use in large-scale industrial production.