Halide-lithium exchange reactions quenching

Reductive Metalation. The powerful reductive nature of this reagent makes it an important tool for lithium-heteroatom exchange reactions. Thus, it was established early on that (phenylthio)alkanes can be converted into their requisite alkyl-lithium species. This has become the method of choice over generation by lithium metal alone. The resultant alkyllithium species can either be quenched with a proton source (eq 1), or intercepted with an electrophile. This has subsequently evolved into a powerful technique, since the reaction is general for all chalcogens (eq 2f and halides (eq 3). ... 

Evidence for the existence of 1-norbornene (72) is strengthened by the following experiments. Dehalogenation of halides (73)—(76), prepared as in Scheme 2, gave in each case in the presence of furan the same ratio of adducts (77) and (78). If in dehalogenation of (73) with t-butyl-lithium the reaction was quenched after a short time with methanol, 2-eniio-bromonorbornane was isolated. Further evidence confirms in each case an initial litWum-iodine exchange followed by elimination. The nature of bonding in the intermediate olefin remains to be established. 

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