Catalytic addition of alkyne C–H, amine N–H, and phosphine P–H bonds to carbodiimides: an efficient route to propiolamidines, guanidines, and phosphaguanidines

Abstract

Various metal complexes (e.g., lanthanides, early transition metals, and alkali metals) can serve as catalyst precursors for the catalytic addition of alkyne C–H, amine N–H, and phosphine P–H bonds to carbodiimides, to give a new family of propiolamidines, guanidines, and phophaguanidines, some of which were difficult to prepare previously. The catalytic reaction proceeds generally through nucleophilic addition of an M–ER (E = CR¹R², NR¹, PR¹) bond, which is formed by an acid–base reaction between a catalyst precursor and a RE–H bond, to a carbodiimide compound, followed by protonolysis of the resultant amidinate–(phospha)guanidinate species “{R′NC(ER)NR′}M” with RE–H.