Copper‐Catalyzed Oxygenative Skeletal Rearrangement of Tetrahydro‐β‐carbolines Using H₂O and O₂ as Oxygen Sources

Abstract

Herein, we report an unprecedented skeletal rearrangement reaction of tetrahydro‐β‐carbolines enabled by copper‐catalyzed single‐electron oxidative oxygenation, in which H2O and O2 act as oxygen sources to generate a unique 2‐hydroxyl‐3‐peroxide indoline intermediate. The synthetic reactivity of 2‐hydroxyl‐3‐peroxide indoline species was demonstrated by a unique multi‐step bond cleavage and formation cascade. Using a readily available copper catalyst under open‐air conditions, highly important yet synthetically difficult spiro[pyrrolidone‐(3,1‐benzoxazine)] products were obtained in a single operation. The synthetic utility of this methodology is demonstrated by the efficient synthesis of the natural products donaxanine and chimonamidine, as well as the 3‐hydroxyl‐pyrroloindoline scaffold, in just one or two steps.