Taming the vinyl carbocation

In the realm of reactivity, the vinyl carbocation is a beast so fleeting, so keen to combine or rearrange, that many have doubted that it can be tamed to create molecules in a stereoselective way. But by confining a vinyl carbocation within a bulky catalyst, chemists have now shown they can coax this wildly reactive intermediate to insert itself into a carbon-hydrogen bond in an enantioselective manner. The work comes from the collaboration of researchers in Hosea M. Nelson's group at the California Institute of Technology, Matthew S. Sigman's group at the University of Utah, and K. N. Houk's group at the University of California, Los Angeles. "Historically, we've really struggled to make these cations catalytically and use them in synthesis," says Sepand K. Nistanaki, a graduate student in Nelson's lab who is the paper's first author. "The fact that these types of carbocations can do this C–H insertion chemistry