1289519-64-7Relevant articles and documents
Regioselective lithium diisopropylamide-mediated ortholithiation of 1-CHLORO-3-(trifluoromethyl)benzene: Role of autocatalysis, lithium chloride catalysis, and reversibility
Hoepker, Alexander C.,Gupta, Lekha,Ma, Yun,Faggin, Marc F.,Collum, David B.
supporting information; experimental part, p. 7135 - 7151 (2011/06/27)
Ortholithiation of 1-chloro-3-(trifluoromethyl) benzene with lithium diisopropylamide (LDA) in tetrahydrofuran at -78 °C displays characteristics of reactions in which aggregation events are rate limiting. Metalation with lithium-chloride-free LDA involves a rate-limiting deaggregation via dimer-based transition structures. The post-rate-limiting proton transfers are suggested to involve highly solvated triple ions. Autocatalysis by the resulting aryllithiums or catalysis by traces (100 ppm) of LiCl diverts the reaction through di- and trisolvated monomer-based pathways for metalation at the 2 and 6 positions, respectively. The regiochemistry is dictated by a combination of kinetically controlledmetalations overlaid by an equilibration involving diisopropylamine that is shown to occur by the microscopic reverse of the monomer-based metalations.
