Rapid and efficient synthesis of formamidines in a catalyst-free and solvent-free system.

An operationally rapid and efficient synthesis of -sulfonyl formamidines that proceeds under mild conditions was achieved by reaction of a mixture of an amine, a sulfonyl azide, and a terminal ynone under catalyst-free and solvent-free conditions. Terminal ynones provide the C source to formamidines complete cleavage of C[triple bond, length as m-dash]C.