Homologation of Alkenes Using Acetylene as a C2 Feedstock.

The preparation of diverse homologs from lead compounds has been a common and important practice in medicinal, mechano, polymeric, and many other branches of chemistry. The homologation of alkenes, though important, remains challenging due to the difficulty of (CH2)n insertion into the main carbon chain of alkenes compared to chains containing other polar functional groups. Here, we report the homologation of both terminal and internal alkenes by using acetylene as a cheap and abundant C2 feedstock. The process involves an in-situ transformation of alkenes into boranes and then into elongated alkenes, during which direct (CH2)n insertion is avoided. The reaction can be carried out iteratively to achieve up to a 12-carbon elongation.