High yields of piperylene in the transfer dehydrogenation of pentane catalyzed by pincer-ligated iridium complexes

Conjugated dienes are desirable reagents for several important applications. We report that sterically uncrowded PCP-pincer iridium complexes, including precursors of ((PCP)-P-iPr4)Ir and ((PCP)-P-Me2tBu2)Ir, catalyze the transfer dehydrogenation of pentane, using high concentrations of t-butylethylene (TBE) as hydrogen acceptor, to give high yields of 1,3-pentadiene (piperylene). Piperylene yields are ca. 100-fold greater than those obtained with the more widely used di(t-butyl)phosphino substituted pincer iridium catalysts. This represents, to our knowledge, the first reported high-yield synthesis of dienes via the dehydrogenation of n-alkane using molecular catalysts. To our knowledge, this is the first reported high-yield synthesis of dienes achieved via the dehydrogenation of n-alkane using molecular catalysts. (C) 2016 Elsevier B.V. All rights reserved.