Abstract:The first visible-light-induced acyl radical Smiles rearrangement to transform biaryl ethers to hydroxybenzophenones under mild and metal-free conditions is reported. Using the dual catalysis of hypervalent iodine(III) reagents and organophotocatalysts, ketoacids readily generate acyl radicals and undergo 1,5-ipso addition. This method can construct electron-deficient and electron-rich hydroxybenzophenones with excellent chemoselectivity and on gram scale. The performance of the reaction in neutral aqueous con… Show more
“…TPT + and ACR + , Figure 2) are strong oxidants in their excited states and have found widespread synthetic applications. [17,[61][62][63][64][65][66][67][68] Surprisingly, in contrast to the wealth of reports dealing with photoexcited cations,t he photochemistry of closed-shell anions has received far less attention, although it constitutes the logical counterpart (Scheme 4E).…”
Utilizing light is a smart way to fuel chemical transformations as it allows the energy to be selectively focused on certain molecules. Many reactions involving electronically excited species proceed via open‐shell intermediates, which offer novel and unique routes to expand the hitherto used synthetic toolbox in organic chemistry. The direct conversion of non‐prefunctionalized, less activated compounds is a highly desirable goal to pave the way towards more sustainable and atom‐economic chemical processes. Photoexcited closed‐shell anions have been shown to reach extreme potentials in single electron transfer reactions and reveal unusual excited‐state reactivity. It is, therefore, surprising that their use as a reagent or photocatalyst is limited to a few examples. In this Review, we briefly discuss the characteristics of anionic photochemistry, highlight pioneering work, and show recent progress which has been made by utilizing photoexcited anionic species in organic synthesis.
“…TPT + and ACR + , Figure 2) are strong oxidants in their excited states and have found widespread synthetic applications. [17,[61][62][63][64][65][66][67][68] Surprisingly, in contrast to the wealth of reports dealing with photoexcited cations,t he photochemistry of closed-shell anions has received far less attention, although it constitutes the logical counterpart (Scheme 4E).…”
Utilizing light is a smart way to fuel chemical transformations as it allows the energy to be selectively focused on certain molecules. Many reactions involving electronically excited species proceed via open‐shell intermediates, which offer novel and unique routes to expand the hitherto used synthetic toolbox in organic chemistry. The direct conversion of non‐prefunctionalized, less activated compounds is a highly desirable goal to pave the way towards more sustainable and atom‐economic chemical processes. Photoexcited closed‐shell anions have been shown to reach extreme potentials in single electron transfer reactions and reveal unusual excited‐state reactivity. It is, therefore, surprising that their use as a reagent or photocatalyst is limited to a few examples. In this Review, we briefly discuss the characteristics of anionic photochemistry, highlight pioneering work, and show recent progress which has been made by utilizing photoexcited anionic species in organic synthesis.
“…Chen and coworkers developed the first acyl radical Smiles rearrangement for transformation of biarylethers into hydroxybenzophenones (Li J. et al, 2019 ) ( Figure 12C ). Under dual hypervalent iodine(III)/photoredox catalysis, α-keto acids undergo ester exchange with BI-OAc to form BI-keto acid complexes in situ , which can readily afford acyl radicals and then suffer 1,5-ipso addition and eventually give hydroxybenzophenones.…”
Section: Hirs Act As Oxidants For Substrate Activationmentioning
The synergistic combination of visible-light-induced photoredox catalysis with hypervalent iodine(III) reagents (HIRs) represents a particularly important achievement in the field of hypervalent iodine chemistry, and numerous notable organic transformations were achieved in a mild and environmentally benign fashion. This account intends to summarize recent synthetic applications of HIRs in visible-light-induced photoredox catalysis, and they are organized in terms of the photochemical roles of HIRs played in reactions.
“…2019,25,[12724][12725][12726][12727][12728][12729] www.chemeurj.org by direct deoxygenation of carboxylic acids by means of photoredox catalysis and phosphoranyl radicals ynergism. Twoe legant acyl radical Smiles examples [13] have been reported, but both required the use of external oxidants, such as di-tertbutyl peroxides( DTBP)o rh ypervalent iodine(III) reagents,t o trigger the generation of acyl radicals. Our deoxygenative arylation strategy reflects as ignificant synthetic advance because it is ar edox-neutral process, has mild reaction conditions and uses readily accessible starting materials.…”
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confidence: 99%
“…Startingw ith o-aminobenzophenones, several important five-to eight-membered heterocyclic skeletons can be easily obtained. As shown in Scheme4a, indole (11), quinoline (12), quinazoline (13), diazepinone (14), and dibenzodiazocine (15) can be constructed, furtheru nderscoring the synthetic value of the o-aminobenzophenones. YaequinoloneA2 ( 17), isolated from Penicillium janczewskii or Penicillium sp.…”
An unprecedented deoxygenative arylationo f aromatic carboxylic acids has been achieved, allowing the construction of an enhanced libraryo fu nsymmetrical diaryl ketones.T he synergistic photoredox catalysis and phosphoranyl radical chemistrya llows for precise cleavage of as tronger CÀOb ond and formation of aw eaker CÀC bond by 1,5-arylm igrationu nder mild reaction conditions. This new protocol is independent of substrate redox-potential,e lectronic, and substituent effects. It affords ag eneral and promising access to 60 examples of synthetically versatile o-amino and o-hydroxyd iaryl ketones under redox-neutral conditions. Furthermore,i ta lso brings one conciser oute to the total synthesis of quinolone alkaloid, (AE)-yaequinolone A2, and av iridicatin derivative in satisfying yields.
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