A new method for the synthesis of selective acylating agents is described from the reaction of carboxylic acids with 3-methyl-1-methylamino-3H-imidazol-1-ium salts in the presence of appropriate coupling reagents. The amides and bis-amides thus prepared reacted selectively with organometallics to afford ketones and diketones and with DIBALH to give aldehydes and dialdehydes in high yields.
[Saba, Shahrokh; Wolff, Steven; Schroeder, Clemens; Margaretha, Paul; Agosta, William C. Journal of the American Chemical Society, 1983 , vol. 105, # 23 p. 6902 - 6907]