One-Pot Stepwise Approach to β‑Enaminoketoesters through “Masked” 1,3-Aza-Dipoles

t-BuOK-mediated
rearrangement of 1,3-ketoesters
with 2-(azidomethyl) aromatics in a two-step, one-pot telescoped sequence
affords β-enaminoketoesters in moderate to good yields. A novel
pathway is proposed in which the umpolung of the azide is achieved
from electrophilicity to nucleophilicity via deprotonation and undergoes
nucleophilic attack onto the 1,3-ketoester.