A cascade intramolecular spirocycloaddition reaction of TBS-O-protected indole-alkynamides
in the presence of a chiral bifunctional thiourea, which involves in situ deprotection,
dearomatization, and intramolecular spirocycloaddition under mild conditions, is developed.
This approach enables the efficient construction of a wide range of polycyclic spiro[indoline-3,3′-piperidin]-6′-one
scaffolds in excellent yields (up to 98%) and with good enantioselectivities (up to
94:6 er).
Keyword
organocatalysis - spiroindolines - dearomatization - spirocycloaddition - cascade
reaction