1,2-carbamoyl migration on enantio-enriched α-lithioalkyl carbamates generated with s-butyllithium/sparteine: Steric course and mechanism

Article abstract of DOI:10.1246/cl.1999.759

Alkyl N,N-diisopropylcarbamates, when lithiated with s-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.