Harenberg JH, Weidmann N, Wiegand AJ, Hoefer CA, Annapureddy RR, Knochel P. (2-Ethylhexyl)sodium: A Hexane-Soluble Reagent for Br/Na-Exchanges and Directed Metalations in Continuous Flow.
Angew Chem Int Ed Engl 2021;
60:14296-14301. [PMID:
33826212 PMCID:
PMC8252725 DOI:
10.1002/anie.202103031]
[Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Indexed: 12/14/2022]
Abstract
We report the on-demand generation of hexane-soluble (2-ethylhexyl)sodium (1) from 3-(chloromethyl)heptane (2) using a sodium-packed-bed reactor under continuous flow conditions. Thus, the resulting solution of 1 is free of elemental sodium and therefore suited for a range of synthetic applications. This new procedure avoids the storage of an alkylsodium and limits the handling of metallic sodium to a minimum. (2-Ethylhexyl)sodium (1) proved to be a very useful reagent and undergoes in-line Br/Na-exchanges as well as directed sodiations. The resulting arylsodium intermediates are subsequently trapped in batch with various electrophiles such as ketones, aldehydes, Weinreb-amides, imines, allyl bromides, disulfides and alkyl iodides. A reaction scale-up of the Br/Na-exchange using an in-line electrophile quench was also reported.
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