In a case study, 1,2,3-trifluorobenzene was functionalized at each of the two vacant positions (producing the benzoic acids 1 and 2) and, in addition, bromine was introduced into all available positions (producing the benzoic acids 3−5). The required regioflexibility was achieved by applying novel orAt first glance, 1,2,3-trifluorobenzene hardly qualifies as a good example for demonstrating the merits of the organometallic approach to the creation of molecular diversity. [1] Having just two regiochemically distinct sites unoccupied, any deprotonation/functionalization sequence can give rise to not more than two isomers. To make our exercise in regioflexibility more demanding, we have therefore allowed for the presence of an additional substituent by targeting both the two trifluorobenzoic acids 1 and 2 and also the three bromo derivatives 3Ϫ5. The chart shown below summarizes the transformations involving the bromo-, iodo-, or triethylsilyl-substituted trifluorobenzenes 6Ϫ14. Details will be specified in the subsequent sections.The ortho-lithiation of 1,2,3-trifluorobenzene with secbutyllithium in tetrahydrofuran at Ϫ75°C has already been reported.[2] Subsequent carboxylation and neutralization afforded 2,3,4-trifluorobenzoic acid (1) in 94% yield.In contrast, a multi-step procedure was required to prepare 3,4,5-trifluorobenzoic acid (2). Treatment of the metalated species with elemental bromine gave 1-bromo-2,3,4-trifluorobenzene (7; 95%), which was converted into (5-bromo-2,3,4-trifluorophenyl)triethylsilane (8; 92%) upon subsequent reaction with lithium diisopropylamide (LIDA) and chlorotriethylsilane. Heating silane 8 with bromine for [a] 36 h in refluxing tetrachloromethane produced 1,5-dibromo-2,3,4-trifluorobenzene (9; 93%). The dibromo compound 9 (95%) was also formed when the bis(silane) 6, resulting in 91% yield from the twofold repetitive reaction