Organoaluminum Catalyzed Guanylation and Hydroboration Reactions of Carbodiimides

Abstract

AbstractHerein, we report the guanylation of carbodiimides with primary and secondary alkyl/aryl amines and the reduction of CDIs via hydroboration using molecular conjugated bis‐guanidinate (CBG) aluminum alkyl catalysts. The first example of structurally characterized unsymmetrical tetra‐aryl substituted CBG (LH) is reported. The reaction of LH; (L={(Ar1NH)(ArN)−C=N−C=(NAr)(NHAr1)}; Ar1=2,6‐iPr2−C6H3, Ar=2,6‐Me2−C6H3) with AlMe3 solution afforded a LAlMe2 (1) complex. The ligand (LH) and compound 1 were thoroughly characterized, including single‐crystal X‐ray diffraction studies. More importantly, compounds 1 and L'AlMe2 (2); (L’={(ArNH)(ArN)−C=N−C=(NAr)(NHAr)}; Ar=2,6‐Et2−C6H3) are utilized as catalysts for N−H and B−H addition to symmetrical aryl or alkyl carbodiimides to obtain the corresponding guanidines and N‐boryl formamidines in excellent yields. The developed catalytic methods are effectively used for the large‐scale synthesis of guanidine and formamidine derivatives under mild reaction conditions.