Variations
Reaction of Weinreb-Nahm amides with Wittig reagents has been performed to avoid the sometimes harsh conditions required for addition of hydride reagents or organometallic compounds. This yields an N-methyl-N-methoxy-enamine that converts to the corresponding ketone or aldehyde upon hydrolytic workup.
Additionally, a one-pot magnesium-halogen exchange with subsequent arylation has been developed, showcasing the stability of the Weinreb-Nahm amide and providing an operationally simple method for the synthesis of aryl ketones.
More unusual reagents with multiple Weinreb-Nahm amide functional groups have been synthesized, serving as CO2 and α-diketone synthons.
Finally, Stephen G. Davies of Oxford has designed a chiral auxiliary that combines the functionality of the Weinreb amide with that of the Myers’ pseudoephedrine auxiliary, allowing diastereoselective enolate alkylation followed by facile cleavage to the corresponding enantioenriched aldehyde or ketone.
Read more about this topic: Weinreb Ketone Synthesis
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