Selective dehydrogenation of small and large molecules by a chloroiridium catalyst.

The dehydrogenation of abundant alkane feedstocks to olefins is one of the mostly intensively investigated reactions in organic catalysis. A long-standing, pervasive challenge in this transformation is the direct dehydrogenation of unactivated 1,1-disubstituted ethane, an aliphatic motif commonly found in organic molecules. Here, we report the design of a diphosphine chloroiridium catalyst for undirected dehydrogenation of this aliphatic class to form valuable 1,1-disubstituted ethylene. Featuring high site selectivity and excellent functional group compatibility, this catalytic system is applicable to late-stage dehydrogenation of complex bioactive molecules. Moreover, the system enables unprecedented dehydrogenation of polypropene with controllable degree of desaturation, dehydrogenating more than 10 in 100 propene units. Further derivatizations of the resulting double bonds afford functionalized polypropenes.