Base-Enabled Access to Diastereoselective Spirofuran Oxindoles and ?-Functionalized Allenoates
Basavaraja D, Ajay Krishna M. S, Jagadeesh Krishnan,a Athira C. S, Amrutha R. R, Eringathodi Suresh, Sasidhar B. Somappa*
Base assisted divergent reactivity of isatins and allenoates has been achieved, which afforded diastereoselective spirofuran oxindoles and ?-functionalized allenoates. DBU mediated Morita-Baylis-Hillman (MBH) reaction followed by the cascade annulation through the stabilized ?-ammonium enolate intermediate led to the spiro-framework. Wherein the DABCO has furnished the ?-functionalized allenoates. The protocol offers access to biologically relevant functionalized oxindole scaffolds with an excellent substrate scope under mild reaction conditions.
Chem. Commun., 2021, 57, 1746-1749.