Catalytic asymmetric α-amination of carboxylic acids using isothioureas

HBTM-2.1 promotes the direct asymmetric alpha-amination of carboxylic acids with N-aryl-N-aroyldiazenes at low catalyst loadings (as low as 0.25 mol%), giving either 1,3,4-oxadiazin-6-ones or N-protected alpha-amino acid derivatives (upon ring opening) with exquisite enantiocontrol (typically >= 99% ee).