Alkyl Aluminum-Catalyzed Addition of Amines to Carbodiimides: A Highly Efficient Route to Substituted Guanidines

The commercially readily available alkyl aluminums, such as AlMe 3, AlEt 3, and AlEt 2 Cl, can serve as excellent catalyst precursors for the catalytic addition of amines to carbodiimides, yielding quantitatively their corresponding trisubstituted guanidines. Aromatic C−X (X = F, Cl, Br, and I) bonds, nitro NO 2, and terminal alkyne units can survive the reaction conditions. An aluminum guanidinate species has been characterized by single-crystal X-ray structural analysis and has been confirmed to be a true catalyst species.