An efficient photoredox‐catalyzed halo‐trifluoromethylation reaction of 1,7‐enynes has been developed under mild conditions. This photocatalytic protocol provides an efficient and functional strategy leading to CF3− and halogen‐containing 3,4‐dihydroquinolin‐2(1H)‐ones from a wide range of 1,7‐enynes through two different radical pathways. The reaction mechanism was proposed based on the control experiments.magnified image

Considering their unique roles in organic synthesis, and pharmaceutical and agrochemical applications, the development of fluoroalkylation, cyclization, and indole oxidative cleavage are important topics. Herein, an unprecedented electrochemical tri‐ and difluoromethylation/cyclization/indole oxidative cleavage process occurring in an undivided cell is presented. The protocol employs a readily prepared Langlois reagent as the fluoroalkyl source, affording a series of tri‐ or difluoromethylated 2‐(2‐acetylphenyl)isoquinoline‐1,3‐diones in good yields with excellent stereoselectivity. It is worth noting that this new methodology merges the fluoroalkylation/cyclization of N‐substituted acrylamide alkenes with the oxidative cleavage of an indole C(2)=C(3) bond under external oxidant‐free conditions.

A process for achieving photocatalyzed tri-and difluoromethylation/cyclizations for constructing a series of tri-or difluoromethylated indole[2,1-a]isoquinoline derivatives is described. This protocol utilized an inexpensive organic photoredox catalyst and provided good yields. Moreover, the combination of continuous flow and photochemistry, designed to provide researchers with a unique green process, was also shown to be key to allowing the reaction to proceed (product yield of 83% in flow vs 0% in batch).

In the present study, we describe the successful development of a photoredox-catalyzed trifluoromethylation/ cyclization of 1,7-enynes in a continuous-flow regime for the generation of several CF 3 -containing heterocyclic scaffolds. When using this protocol, a readily prepared Ph 2 SCF 3 OTf reagent was employed as the trifluoromethylation reagent, and various benzo-[j]phenanthridines and indeno[1,2-c]quinolines were obtained in good to moderate yields. This transformation featured mild reaction conditions, a broad substrate scope, and ease of scale-up. Moreover, the continuous-flow processing in a photomicroreactor accelerated the reaction (5 min reaction time) and increased the product yields (up to 89%).

Comprehensive Summary A three‐component reaction of 1,3‐enynes and cyclobutanone oxime esters in the presence of aryl boronic acids or organozinc reagents via the photoredox/copper or photoredox/nickel catalysis has been established. This redox‐neutral 1,4‐cyanoalkylarylation reaction has demonstrated mild condition, high catalytic reactivity and wide functional group compatibility, allowing access to a variety of functionalized tetra‐substituted allene derivatives with high chemo‐ and regioselectivity. Moreover, using photocatalytic continuous flow technique to promote this process would result in increased yields (70% in flow vs. 61% in batch), reduced reaction times (7 min in flow vs. 6 h in batch), and easy scale‐up (upgrade to gram scale), showcasing its potential as a synthetic platform.