Turbo-Hauser reagents

Fig. 6 Synthetic protocols for forming Turbo-Grignard (D) and Turbo-Hauser reagents (A, B and C)...

While the Turbo-Grignard reagents are proficient at metal-halogen exchange, the amide-based Turbo-Hauser reagents are more useful in selective metal-hydrogen... 

The excellent direct magnesiating properties of Turbo-Hauser reagent A extends beyond the confines of aromatic substrates (though these are by far the most frequently encountered substrates in such transformations). For example, the ether-functionalised ester, ethyl 2-ethoxyacrylate, can be selectively magnesiated in a reaction favoured by the stabilising effect of the adjacent carbonyl group, with work-up of the reaction mixture affording a non-aromatic cyclic lactone in an excellent yield (Fig. 16) [39]. 

In cases where a stronger base than Turbo-A is required (generally when the organic substrate has a high pAa value), the bis-amido Hauser reagent (TMP)2Mg-2LiCl (B), equipped with two active base units, can be employed. Its enhanced reactivity (higher kinetic basicity) is demonstrated indirectly by the... 

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