Stereoselective Preparation
of Cyclopropylmagnesium Reagents via a Br-Mg
Exchange Using <i>i</i>-PrMgCl×LiCl
in the Presence of Dioxane

Rauhut, Christian B.; Cervino, Christian; Krasovskiy, Arkady; Knöchel, Paul

doi:10.1055/s-0028-1087487

Cited by 4 publications

References 6 publications

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Mixed Lithium Complexes: Structure and Applicationin Synthesis

Mulvey

O’Hara

2014

Lithium Compounds in Organic Synthesis

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IntroductionFor half a century, organolithium (C-Li bonded) reagents and lithium amides (N-Li bonded) have played a pivotal role in the development of modern day synthetic chemistry. Reagents in these categories, in particular the butyllithiums (the normal-, secondary-, and tertiary-isomers), lithium diisopropylamide (LDA), lithium 2,2,6,6-tetramethylpiperid-1-ide (LiTMP), and lithium 1,1,1,3,3,3-hexamethyldisilazide (LiHMDS) are utilized in most synthetic laboratories around the world and are especially important in the metallation reaction (that is, the conversion of a relatively inert C-H bond into a more reactive (more chemically pliable) C-Li bond) and in the kinetically operative metal-halogen exchange reactions. The past two decades have witnessed several new classes of constitutionally more complex reagents that contain multimetal and/or multianion formulations that have challenged the dominance of these unimetallic/unianionic reagents in deprotonative/metal-halogen exchange chemistry. This chapter covers some of the rich structural and synthetic chemistry of these new and still emerging systems, detailing only a small selection of what these classes of compounds can offer the chemist at the present time. Structural Chemistry of Heterometallic Lithium ComplexesStructure is inextricably and mutually linked to reactivity; hence, much recent research activity has focused on the elucidation of solid-state and solution structures of lithium organometallics and amides. This section concentrates on the structural chemistry of lithium-containing mixed-metal complexes, focusing particularly on mixed s-block (Group 1/Group 1 or Group 1/Group 2) complexes, and those containing the Group 12 d 10 metal zinc, which is commonly regarded as a displaced alkaline earth metal. In recent years, heterometallic sodium reagents (particularly sodium zincates, magnesiates, aluminates, etc.) have received a great Lithium Compounds in Organic Synthesis: From Fundamentals to Applications, First Edition. Edited by Renzo Luisi and Vito Capriati.

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Mixed Lithium Complexes: Structure and Applicationin Synthesis

Mulvey

O’Hara

2014

Lithium Compounds in Organic Synthesis

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ChemInform Abstract: Stereoselective Preparation of Cyclopropylmagnesium Reagents via a Br—Mg Exchange Using i‐PrMgCl·LiCl in the Presence of Dioxane.

et al. 2009

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Cyclopropane derivatives Q 0021 Stereoselective Preparation of Cyclopropylmagnesium Reagents via a Br-Mg Exchange Using i-PrMgCl·LiCl in thePresence of Dioxane. -Subsequent quenching with electrophiles offers a stereoselective synthesis of functionalized cyclopropanes with retention of the bromide stereochemistry. -(RAUHUT, C. B.; CERVINO, C.; KRASOVSKIY, A.; KNOCHEL*, P.; Synlett 2009, 1, 67-70;

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Minimal Theoretical Description of Magnesium Halogen Exchanges

Pham,

Bui,

Foreman

2023

Organometallics

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Although Grignard exchange reactions have been known for about a century, little beyond heuristics guides the prediction of when and where an exchange will occur. Additionally, little is understood from a modeling perspective about why the heuristics work or when they might fail. We develop a simple quantum mechanical model for predicting when and where an exchange will occur. We show that the solvent-free model successfully predicts for reactions regioselectively using only thermodynamic end points. After validating the model, we employ it to explain some of the heuristic understandings, such as preference for exchanging with halogens lower on the periodic table and facilitation of the exchange with lithium chloride. Preference for bromine over chlorine appears to be related to both kinetic barriers and thermodynamic considerations, and addition of lithium chloride to the exchange mixture appears to act almost exclusively in a catalytic role. We then use the model to predict materials that should allow ready exchange onto any carbon, including tertiary halide carbons. We find that removable silicon-linked directing ethers attached to the molecule of interest and, potentially more versatilely, silyl Grignard reagents could serve in this role.

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Stereoselective Preparation of Cyclopropylmagnesium Reagents via a Br-Mg Exchange Using i-PrMgCl×LiCl in the Presence of Dioxane

Abstract: The reaction of various cyclopropyl bromides with i-PrMgCl·LiCl in THF-dioxane provides the corresponding magnesiated cyclopropane reagents with complete retention of configuration.

Cited by 4 publications

References 6 publications

Mixed Lithium Complexes: Structure and Applicationin Synthesis

Mixed Lithium Complexes: Structure and Applicationin Synthesis

ChemInform Abstract: Stereoselective Preparation of Cyclopropylmagnesium Reagents via a Br—Mg Exchange Using i‐PrMgCl·LiCl in the Presence of Dioxane.

Minimal Theoretical Description of Magnesium Halogen Exchanges

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