Catalyst-Controlled Diastereodivergent Synthesis of Dispiro Compounds via Formal (3 + 2) Cyclization

Mg/Pd-catalyzed the same formal (3 + 2) cycloaddition of spirovinylcyclopropyl oxindoles and 2-arylidene-1,3-indanediones was realized for the first time. The protocol enables access to two diastereomers of dispiro pentacyclic compounds in good to excellent yields (up to 94%) with acceptable dr (up to >20:1:0:0 dr). Based on experimental results and a high-resolution mass spectrometry experiment, a plausible reaction mechanism and a tentative model of Mg-/Pd-controlled diastereosegregation have been proposed, revealing the reason for the highly diastereoselective generation of the major product.