Design and Synthesis of Fluoro‐containing Hypervalent Iodane (III) Reagents for Visible‐light‐triggered Cyclization of Alkynoates to 3‐Fluoroalkylated Coumarins

Abstract

A series of novel fluoro‐containing hypervalent iodane (III) reagents was designed and synthesized. By employing these novel hypervalent iodane (III) reagents, an efficient visible‐light‐triggered radical cyclization of alkynoates to diversely 3‐fluoroalkylated coumarins was developed under metal free condition. It provided an alternative and environmental friendly approach for the installation of 3‐fluoroalkyl motif into synthetically valuable building block coumarins.

Recent Advances in Visible Light‐Mediated Radical Fluoro‐alkylation, ‐alkoxylation, ‐alkylthiolation, ‐alkylselenolation, and ‐alkylamination

“…These two protocols provide the compounds in great yields in the absence of exogenous oxidants, photocatalysts, or electrochemical setups, which have been previously used for the synthesis of difluoromethylated 2‐oxindoles. Similar additive‐free difluoromethylation protocols were reported by Lu and coworkers to provide difluoromethyl dihydroisoquinolinones, spiro[4.5]trienones, and coumarins all utilizing additive‐free conditions [63–65] . A reduction with a photocatalyst can also provide the decarboxylative radical generation, as shown by Zhu, Wu, and coworkers in their difluoromethylated dibenzazepine synthesis [66] .…”

“…Similar additive-free difluoromethylation protocols were reported by Lu and coworkers to provide difluoromethyl dihydroisoquinolinones, spiro [4.5]trienones, and coumarins all utilizing additive-free conditions. [63][64][65] A reduction with a photocatalyst can also provide the decarboxylative radical generation, as shown by Zhu, Wu, and coworkers in their difluoromethylated dibenzazepine synthesis. [66] He and coworkers reported the synthesis of difluoromethyl ring fused quinazolinones under violet light irradiation utilizing 16, which was generated in situ.…”

Visible-Light-Induced C-3 Difluoroalkylation of Quinoxalin-2(1H)-ones with Difluoroiodane(III) Reagents under Catalyst-Free Conditions

“…With these fluorinated iodane(III) reagents in hand, we developed a photoinduced three-component difluoroalkylation of quinoxalinones with alkenes, a visiblelight-triggered radical cyclization of alkynoates to 3-fluoroalkylated coumarins, and a visible-light-induced hydrodifluoroalkylation of alkenes and alkynes. [14][15][16] Herein, we report a visible-light-induced C(3) difluoroalkylation of quinoxalin-2(1H)-ones 1 with these difluoroiodane(III) reagents under catalyst-free conditions (Scheme 1, equation 7).…”

Progress in the Construction of Spirocyclohexadienones via Alkyne-Involving Dearomatization

“…该方法条件 温和, 反应时间短. 同年, 芦逵等 [14] 报道了可见光条件 周全等 [15] 于 2018 年报道了可见光条件下以磺酰氯 化合物为磺酰基自由基前体的丙炔酰胺的磺酰化螺环 化反应, 得到了一系列 3-磺酰基螺 [4,5]三烯酮衍生物. 除了直接以磺酰氯作为前体外, 也有利用三组分合成磺 化螺 [4,5]三烯酮的方法被报道.…”