That's the feeling I got reading through a recent JACS ASAP, from the Chen group at PSU. They've been playing with an easy-to-remove C-H activation auxiliary (PA) first developed by Daugulis back in 2005. They've taught it some pretty neat tricks thus far: C-H amination, alkoxylation, and even alkylation reactions using simple primary iodides.
Their latest extends the chemistry to methyl iodide, which, when combined with some silver salts and a phosphate additive, usually plunks a new CH3 on an unhindered, kinetically-accessible gamma-methyl (i.e. the chain grows by one). However, in the case of norbornene, something wild happens: the Pd catalyst activates a secondary C-H bond, sticks a methyl on, but doesn't stop there; it "bites" into the newly formed methyl and adds on two more, to produce an isopropyl group. Sweet!
Source: JACS ASAP 2013 | Chen group, PSU
|O Norbornene Tree, O Norbornene Tree;|
I do not grok your sterics.
Readers, can someone disabuse me of this crazy notion?