Aliphatic organolithiums by fluorine-lithium exchange: n-octyllithium

The reaction of 1-fluorooctane (1) with an excess of lithium powder (4-10 equiv.) and DTBB (2-4 equiv.) in THP at 0°C for 5 min gives a solution of the corresponding 1-octyllithium (2), which reacts then with different electrophiles at 0°C (D₂O, MeSiCl, Bu^tCHO, Et₂CO), or −78°C ClCO₂Me, (PhCH₂S)₂] or −40°C (CO₂) to room temperature to give, after hydrolysis, the expected products (3). The same process applied to 2-fluorooctane gives mainly octane as reaction product, independently on the electrophile used, resulting from a proton abstraction by 2-lithiooctane formed from the reaction medium before addition of the electrophilic reagent.