Synthesis of Dialkyl 2-(Alkylamino)-4,9-dihydro-9-oxocyclohepta[b]pyran-3,4-dicarboxylates

Dialkyl 2-(alkylamino)-4,9-dihydro-9-oxocyclohepta[b]pyran-3,4-dicarboxylates are prepared in a one-pot three-component reaction of alkyl isocyanide, dialkyl acetylenedicarboxylate, and α-tropolone (=2-hydroxycyclohepta-2,4,6-trienone). The reaction proceeds smoothly at room temperature and under neutral conditions to afford tropolone derivatives in high yield.