Synthesis of 6-substituted phenanthridines by metal-free, visible-light induced aerobic oxidative cyclization of 2-isocyanobiphenyls with hydrazines

Abstract

Irradiation of hydrazines and 2-isocyanobiphenyls with visible-light in the presence of organic dye eosin B generates various 6-substituted phenanthridines in good yields.

Metal‐Free Preparation of 6‐Alkylthiophenanthridines via Oxidative CS and CC Bond Formation from 2‐Isocyanobiphenyls and Disulfides

“…In the past two years, aryl isocyanides have gained renewed attention as they can serve as efficient radical acceptors in cascade reactions for the rapid construction of phenanthridine derivatives, which belong to an important class of biological compounds and widely feature in natural products. [8] However, only a few radical precursors have been developed for this reaction, such as boronic acids, [9] trifluoromethylation reagents, [10] halides, [11] aldehydes, [12] diphenylphosphine oxide, [13] a-oxocarboxylic acids, [14] hydrazines, [15] and aryl sulfonyl chlorides. [16] Very recently, cyclization of isocyanides with alkanes, alcohols, and ethers via CA C H T U N G T R E N N U N G (sp 3 ) À H bond cleavage has been reported.…”

Visible-light-mediated trifluoroethylation of 2-isocyanobiaryl with trifluoroethyl iodide: Synthesis of 6-trifluoroethyl-phenanthridines

“…On the basis of the experimental observation and literatures [44][45][46][47][48][49][50][51][52][53] …”

“…For instance, Carreira reported a cobaltcatalyzed photochemical synthesis of allylic trifluoromethanes from styrene derivatives using 2,2,2-trifluoroethyl iodide [38]. On the basis of this work and in connection with our interest radical cyclizations [39][40][41][42][43], we communicate herein our recent studies on the visible-light-promoted trifluoroethylation of 2-isocyanobiaryl using the cheap and available reagent CF 3 CH 2 I as the source of the CH 2 CF 3 group to afford 6-trifluoroethyl-phenanthridine derivatives (Scheme 1) [44][45][46][47][48][49][50][51][52][53].…”

Synthesis ofN-Containing Heterocyclic Compounds Using Visible-light Photoredox Catalysis

“…Very shortly after Yu's report, our group disclosed a visible‐light‐induced radical cyclization of 2‐isocyanobiphenyls 111 with hydrazines 112 (Scheme ) . This reaction proceeded under metal‐free conditions by using inexpensive and easily available eosin B as a photoredox catalyst.…”