Chemoselective Synthesis of a-Chloro and a,a -Dichloro acetamidines via the Carbenoids Addition to Inherently Low Electrophilic Carbodiimides

The hitherto few explored α-halomethyl amidine motif has been assembled through the addition of a lithiated (di)-halomethane (i.e., carbenoid) to easily accessible N,N’-diaryl-substituted carbodiimides. Despite the inherent low electrophilicity of these heterocumulenes—as quantitatively determined in Mayr's previous studies—their sp-hybridized carbon atom acts as a competent site of attack for these tamed nucleophiles. The overall high-yielding transformation featuring a genuine chemoselective profile—as documented by using variously functionalized materials—is adaptable to the addition of dihalogenated carbenoids. Reaction products could be advantageously used in nucleophilic substitution sequences as well as in further functionalization of the nitrogen atoms due to the constitutive heteroallyl-type skeleton.