A Facile Synthesis of 2‐Methyl‐3‐oxoindoline‐2‐carboxylates Utilizing Aza‐Brook Rearrangement as a Crucial Step

Abstract

Synthesis of 2‐methyl‐3‐oxoindoline‐2‐carboxylates is developed using a bis(trimethylsilyl)aluminum chloride‐induced aza‐Brook rearrangement as a crucial step. Regarding the organoaluminum species, use of readily available tris(trimethylsilyl)aluminum·ether complex was not suitable for the present cyclization. After a series of examination of the reaction conditions, the aza‐Brook rearrangement and the subsequent cyclization with 2 equivalens of bis(trimethylsilyl)aluminum chloride were found to be the most effective. An application to the synthesis of a potential intermediate of duocarmycin A is also described, in which ozonolysis of the styrenyl moiety and the Barton–McCombie deoxygenation of the hydroxymethyl group were successfully carried out.

Concise Unified Access to (−)-8-Deoxy-13-dehydroserratinine, (+)-Fawcettimine, (+)-Fawcettidine, and (−)-8-Deoxyserratinine Using a Direct Intramolecular Reductive Coupling

“…With the cyclic imine 25 in hand, we started to explore the crucial intramolecular reductive imine–ester coupling (Table ). Although several electrochemical approaches were reported for similar intramolecular couplings of aromatic imines and esters, few have been explored on the corresponding aliphatic system, especially a complex aliphatic system that contains multiple continuous stereocenters. As a category of powerful reductants involving single-electron processes, lithium-arenides were employed in some challenging C–C bond formations. , Due to the uncertainty of the reductive C–C coupling between an aliphatic imine and an ester, metal–arene-based conditions were chosen by us as a feasible starting point for the examination.…”