Direct Synthesis of Dialkyl Ketones from Aliphatic Aldehydes through Radical N-Heterocyclic Carbene Catalysis

A designed thiazolium-type N-heterocyclic carbene (NHC) catalyst having an N-neopentyl group and seven-membered backbone structure was achieved through the use of aliphatic aldehydes as acyl donors in the decarboxylative radical coupling with aliphatic carboxylic acid derived-redox active esters. The NHC catalyst also enabled the vicinal alkylacylation of vinyl arenes using aliphatic aldehydes and redox-active esters through a radical relay mechanism. These reactions provided the synthetic route to sterically hindered dialkyl ketones.