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

Wen-Xiong Zhang, Zhaomin Hou

Index: Org. Biomol. Chem. 6(10) , 1720-30, (2008)

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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 phosphaguanidines, some of which were difficult to prepare previously. The catalytic reaction proceeds generally through nucleophilic addition of an M-ER (E=CR(1)R(2), NR(1), PR(1)) 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.