Zirconium and hafnium catalyzed C-C single bond hydroboration.

Abstract

Selective cleavage and subsequent functionalization of C-C single bonds present a fundamental challenge in synthetic organic chemistry. Traditionally, the activation of C-C single bonds has been achieved using stoichiometric transition-metal complexes. Recently, examples of catalytic processes were developed in which use is made of precious metals. However, the use of inexpensive and Earth-abundant group IV metals for catalytic C-C single-bond cleavage is largely underdeveloped. Herein, the zirconium-catalyzed C-C single-bond cleavage and subsequent hydroboration reactions is realized using Cp₂ZrCl₂ as a catalytic system. A series of structures of various γ-boronated amines are readily obtained, which are otherwise difficult to obtain. Mechanistic studies disclose the formation of a N-Zr^IV species, and then a β-carbon elimination route is responsible for C-C single bond activation. Besides zirconium, hafnium exhibits a similar performance for this transformation.