Abstract

Magnesium organometallic reagents occupy a central position in organic synthesis. Freshness of these compounds is key for achieving high conversion and reproducible results. Common methods for the synthesis of Grignard reagents from metallic magnesium present safety issues and exhibit batch-to-batch variability. Tubular reactors of solid-reagents combined with solution phase reagents enable the continuous-flow preparation of organomagnesium reagents. The use of stratified packed bed columns of magnesium and lithium chloride for the synthesis of highly concentrated turbo Grignards is reported. A low-cost pod-style synthesizer prototype, which incorporates single-use prepacked perfluorinated cartridges and bags of reagents, for the automated on-demand lab-scale synthesis of carbon, nitrogen and oxygen turbo magnesium bases is presented. This concept will provide access to fresh organomagnesium reagents on a discovery scale and will do so independent of operator’s experience in flow and/or organometallic chemistry. 

Keywords: Turbo Grignard Reagent; Knochel-Hauser Base; Magnesium; Lithium chloride; On-demand; Packed bed reactors; Plug and flow reactor; Synthesizer

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Berton, M.; Sheehan, K.; Adamo, A.; McQuade, D. T. Beilstein Arch. 2020, 202040. doi:10.3762/bxiv.2020.40.v1