Metal-Free and Regioselective Synthesis of Functionalized α-Carbolines via [3+3] Annulation of Morita-Baylis-Hillman Acetates of Nitroalkenes with Iminoindolines

A facile, metal-free method for the synthesis of substituted alpha-carbolines from secondary Morita-Baylis-Hillman (MBH) acetates of nitroalkenes is presented. The cascade reaction of MBH acetates with tosyliminoindolines occurs regioselectively to form various alpha-carbolines with a wide substrate scope. The reaction involves mild conditions, and the products are formed in high yields within a short reaction time. The amenability of the reaction to scale up and synthetic applications of the products have been demonstrated.

Automated summary

This study presents a facile, metal-free method for the synthesis of substituted alpha-carbolines from secondary Morita-Baylis-Hillman acetates of nitroalkenes. The regioselective cascade reaction of MBH acetates with tosyliminoindolines leads to the formation of various alpha-carbolines with a wide substrate scope. The reaction occurs under mild conditions and yields products in high amounts within a short reaction time, showing scalability and potential synthetic applications.