Turbo-Hauser bases

These mixed Mg/Li amides of the type R2NMgCl⋅LiCl are used in organic chemistry as non-nucleophilic bases for metalation reactions of aromatic and heteroaromatic substrates.

Compared to their LiCl free ancestors Turbo-Hauser bases show an enhanced kinetic basicity, excellent regioselectivity, high functional group tolerance and a better solubility.

[1] Typically Turbo-Hauser bases are prepared by treating an amine with a Grignard reagent and lithium chloride.

Diffusion-Ordered Spectroscopy (DOSY) show that at room temperature and high concentrations (0.6 M) dimeric [iPr2NMgCl·LiCl]2 remains intact solution.

[2][3] The iPr-Turbo-Hauser base crystallizes as a dimeric amido bridged contact ion pair (CIP).

The regioselective ortho deprotonation reactions of TMPMgCl·LiCl could stem from a sufficient complex-induced proximity effect (CIPE) between the bimetallic aggregate and the functionalized (hetero)aromatic substrate.

i Pr- Turbo -Hauser Base in the solid state
TMP- Turbo -Hauser Base in the solid state
Contrasting reactivity of i Pr 2 NMgCl·LiCl and TMPMgCl·LiCl
Contrasting reactivity of i Pr 2 NMgCl·LiCl and TMPMgCl·LiCl
Proposed complex-induced proximity effect (CIPE) in a TMPMgCl·LiCl mediated reaction