Unusual [3+2] Spiroannulation and Creation of Stereogenic Quaternary Center at C-3 of Oxindole via Addition of (Het)arynes to Isomerized Morita-Baylis-Hillman Adduct of Isatin

摘要

A one-pot synthesis of 1'-methyl-2'-oxospiro [indene-1,3'-indoline] and 3,3-disubstituted 2-oxindole derivatives in excellent combined yield by the reaction of methoxy isomerized MBH adducts of isatin with arynes and heteroarynes has been achieved. A plausible mechanism invoking a [3+2]-spiroannulation reaction and quenching the intermediate with proton is explained. Formation of regioselective products from unsymmetrical arynes is explained based on reactivity profiles of arynes/heteroarynes. Synthetic utility of synthesized compounds have been demonstrated.