Phosphine-Catalyzed Synthesis of 3,3-Spirocyclopenteneoxindoles from γ‑Substituted Allenoates: Systematic Studies and Targeted Applications

The phosphine-promoted [3 + 2] cyclizations between γ-substituted allenoates and arylideneoxindoles have been applied to the stereoselective synthesis of spiro(cyclopentene)oxindoles with trisubstituted cyclopentene units. It has been demonstrated that PPh3 operates a very efficient control of the relative stereochemistry of the three stereogenic centers of the final spiranic products. Focused experiments have been carried out then so as to access carbocyclic analogues of an important series of anticancer agents inhibiting MDM2-p53 interactions.