Simple, versatile, and efficient catalysts for guanylation of amines

Abstract

Commercially available products such as ZnEt2 (1), MgBu2 (2), and n-BuLi (3) can act as excellent catalytic precursors for the catalytic addition of amines to carbodiimides. Aromatic primary amines bearing different substituents, secondary amines, and heterocyclic amines can undergo this reaction. The synthesis and structural characterization of the zinc guanidinate complex [Zn(Et){(4-t-BuC6H4)N═C(N-i-Pr)(NH-i-Pr)}]2 (15) and the synthesis and characterization of the lithium guanidinate complex [Li{(2,4,6-Me3C6H4)N═C(N-i-Pr)(NH-i-Pr)}(THF)] (16), both of which act as catalysts in the guanylation reaction, allowed us to propose a mechanism involving the formation of amido intermediates. These amido compounds subsequently react with the carbodiimide in an insertion process.