34689-96-8Relevant articles and documents
Untangling the Complexity of Mixed Lithium/Magnesium Alkyl/Alkoxy Combinations Utilised in Bromine/Magnesium Exchange Reactions
Bole, Leonie J.,Judge, Neil R.,Hevia, Eva
supporting information, p. 7626 - 7631 (2021/03/08)
While it is known that the addition of Group 1 alkoxides to s-block organometallics can have an activating effect on reactivity, the exact nature of this effect is not that well understood. Here we describe the activation of sBu2Mg towards substituted bromoarenes by adding one equivalent of LiOR (R=2-ethylhexyl), where unusually both sBu groups can undergo efficient Br/Mg exchange. Depending on the substitution pattern on the bromoarene two different types of organometallic intermediates have been isolated, either a mixed aryl/alkoxide [{LiMg(2-FG-C6H4)2(OR)}2] (FG=OMe; NMe2) or a homoaryl [(THF)4Li2Mg(4-FG-C6H4)4] (FG=OMe, F). Detailed NMR spectroscopic studies have revealed that these exchange reactions and the formation of their intermediates are controlled by a new type of bimetallic Schlenk-type equilibrium between heteroleptic [LiMgsBu2(OR)], alkyl rich [Li2MgsBu4] and Mg(OR)2, with [Li2MgsBu4] being the active species performing the Br/Mg exchange process.