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Halogen sodium zinc carbon dance

31 May 2020 - Orgo

asako 2020 organosodium2.PNGInteresting halogen sodium zinc carbon dance reported by Sobi Asako et al (DOI) and a new chapter in a long standing lithium sodium feud. Basic idea, sodium could replace lithium in just about any organolithium application because sodium is cheaper and organosodium unlike lithium has been around since the 1840's. The innovation: the starting organosodium compound is made from neopentyl chloride and a metallic sodium dispersion in paraffin and hexane / 0°. Then this in-situ neopentylsodium can dance with just any other organohalogen and in this way an avenue is opened for lots and lots of organosodium compounds. Thus tossing in 1-bromonaphthalene afterwards yields sodium naphthalenide and then by adding zinc dichloride.TMEDA zinc naphthalenide. As a further demonstration this compound was then used in a typical Negishi coupling with methyl 4-chlorobenzoate and palladium catalyst PEPPSI.
The article is in ChemRxiv stage, a reviewer might ask two questions, one trivial, if you say hexane what hexane variety do you mean exactly ? and the other actually relevant, what does the sodium dispersion look like? It is supplied by two commercial suppliers and although the authors note that it can be made in a home brew the article lacks the technical details.