Photocyclization of enamines to access Spiroindolines and Spirooxindoles in continuous flow
作者:Moses Moustakim、Brian Ledford、Jacob A. Garwin、Michael J. Boyd
DOI:10.1016/j.tetlet.2020.152111
日期:2020.7
We report an expedited flow chemistry approach to the catalyst/photosensitizer-free UV photocyclizations of aryl-enamines to afford spiroindolines. The photocyclizations occur under mild conditions and are tolerant to a variety of substituted aryl-enamines and spirocycle ring sizes. This flow protocol has a wide substrate scope and addresses the problems of irreproducibility and scalability of batch
The reaction between primary amines and 2-bromo-2-(cycloalkylidene)acetates in alcohol under high pressure provides the expected spiroaziridines in good yields and diastereomeric excesses. With bulky or aromatic amines, this reaction competes with the migration of the double bond, which, migrating from an exo to an endocyclic position, provides an intermediate allylic α-bromo ester, immediately converted