exchange in aqueous potassium hydroxide. Lithium tridecafluorobicyclo[2.2.2]octyl has been formed using methyllithium in ether at − 50° and reacted with deuterium oxide, methyliodide and iodine to give the 1-deutero-, 1-methyl- and 1-iodo-tridecafluorobicyclo[2.2.2]octanes; it was unchanged after 1 hr at 35° and hence represents the most stable perfluoro alkyl lithium so far prepared.