Direct transformation of -alkane into all- conjugated polyene via cascade dehydrogenation.

Selective C(sp) -H activation is of fundamental importance in processing alkane feedstocks to produce high-value-added chemical products. By virtue of an on-surface synthesis strategy, we report selective cascade dehydrogenation of -alkane molecules under surface constraints, which yields monodispersed all- conjugated polyenes with unprecedented length controllability. We are also able to demonstrate the generality of this concept for alkyl-substituted molecules with programmable lengths and diverse functionalities, and more importantly its promising potential in molecular wiring.