1, 2-Carbamoyl Migration on Enantio-enriched α-Lithioalkyl Carbamates Generated with s-Butyllithium/Sparteine:Steric Course and Mechanism
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Alkyl <I>N</I>,<I>N</I>-diisopropylcarbamates, when lithiated with <I>s</I>-BuLi/(−)-sparteine in ether at −78 °C followed by warming to room temperature, are shown to undergo the 1,2-carbamoyl migration to give the α-hydroxy amides in >95% ee with complete retention of configuration at the Li-bearing carbanion terminus. An addition-elimination mechanism is proposed.
- Chemistry Letters
Chemistry Letters 1999(8), 759-760, 1999-08-05
The Chemical Society of Japan