Abstract:Enantioselective photocatalysis has rapidly grown into a powerful tool for synthetic chemists. This review describes the various strategies for creating enantioenriched products through merging enantioselective catalysis and photocatalysis, with a focus on the most recent developments and a particular interest in the proposed mechanisms for each. With the aim of understanding the scope of each strategy, to help guide and inspire further innovation in this field.
“…Another noteworthy kind of reactions involve the enantioselective functionalization of activated α-carbonyl C( sp 3 )–H bonds via radical addition to the corresponding enolate 9 – 12 or enamine 13 , 14 intermediates. Although significant, most of these reactions 15 , 16 do not involve C–H-derived radical species and thus are out of the scope of this Perspective unless otherwise discussed below. Fig.…”
Recently, with the boosted development of radical chemistry, enantioselective functionalization of C(sp3)–H bonds via a radical pathway has witnessed a renaissance. In principle, two distinct catalytic modes, distinguished by the steps in which the stereochemistry is determined (the radical formation step or the radical functionalization step), can be devised. This Perspective discusses the state-of-the-art in the area of catalytic enantioselective C(sp3)–H functionalization involving radical intermediates as well as future challenges and opportunities.
“…Another noteworthy kind of reactions involve the enantioselective functionalization of activated α-carbonyl C( sp 3 )–H bonds via radical addition to the corresponding enolate 9 – 12 or enamine 13 , 14 intermediates. Although significant, most of these reactions 15 , 16 do not involve C–H-derived radical species and thus are out of the scope of this Perspective unless otherwise discussed below. Fig.…”
Recently, with the boosted development of radical chemistry, enantioselective functionalization of C(sp3)–H bonds via a radical pathway has witnessed a renaissance. In principle, two distinct catalytic modes, distinguished by the steps in which the stereochemistry is determined (the radical formation step or the radical functionalization step), can be devised. This Perspective discusses the state-of-the-art in the area of catalytic enantioselective C(sp3)–H functionalization involving radical intermediates as well as future challenges and opportunities.
“…A variety of α,β-unsaturated carbonyl compounds with electronically varied β-aryl substituents (2-9) were accommodated, producing the corresponding cycloadducts in high yields and selectivities. Substrates with substituents at the ortho position (3,7) reacted slower than corresponding substrates with meta or para substitution but were formed in higher diastereoselectivity. A thienyl substrate (11) reacted efficiently.…”
Section: Resultsmentioning
confidence: 99%
“…A defining characteristic of modern synthetic chemistry is the capacity to conduct complexity-building organic reactions with high levels of stereocontrol. The strategies available to dictate the stereochemical outcome of photochemical reactions, however, remain significantly underdeveloped compared to other classes of organic reactions [1][2][3][4][5][6][7][8] . The difficulty of conducting asymmetric photochemical reactions has often been attributed to the very short lifetimes and high reactivities associated with electronically excited compounds; these features challenge the ability of catalysts to intercept and modulate the behavior of organic excited states.…”
Control over the stereochemistry of excited-state photoreactions remains a significant challenge in organic synthesis. Recently, it has become recognized that the photophysical properties of simple organic substrates can be altered upon coordination to Lewis acid catalysts, and that these changes can be exploited in the design of highly enantioselective catalytic photoreactions. Chromophore activation strategies, wherein simple organic substrates are activated towards photoexcitation upon binding to a Lewis acid catalyst, rank among the most successful asymmetric photoreactions. Herein, we show that chiral Brønsted acids can also catalyze asymmetric excited-state photoreactions by chromophore activation. This principle is demonstrated in the context of a highly enantio- and diastereoselective [2+2] photocycloaddition catalyzed by a chiral phosphoramide organocatalyst. Notably, the cyclobutane products arising from this method feature a trans-cis stereochemistry that is complementary to other enantioselective catalytic [2+2] photocycloadditions reported to date.
“…The photocatalytic mechanism of CDs can be the photoexcitation and charge separation of the core carbon. [ 20 ] In general, the photocatalytic process based on CDs is divided into the following three processes. First, the absorption of light leads to the generation of electron‐hole pairs.…”
Section: Introductionmentioning
confidence: 99%
“…The introduced CDs broadened the response range of the spectrum, promoted the separation of electron-hole pairs, and enhanced the photocatalytic efficiency.The photocatalytic mechanism of CDs can be the photoexcitation and charge separation of the core carbon. [20] In general, the photocatalytic process based on CDs is divided into the following three processes. First, the absorption of light leads to the generation of electron-hole pairs.…”
extensive research in the fields of drug delivery, chemical sensing, bioimaging, and specifically catalysis. [7][8][9] For instance, Liu's group has prepared CDs-confined CoP-CoO nanoheterostructure, Ru@CDs, RuM/CDs (M = Ni, Mn, Cu), and RuCo/ CDs catalysts with excellent catalytic performance, which can be widely used for electrolysis of hydrogen. [10][11][12][13] Catalysis, especially photocatalysis, is a topic that has received a lot of attention recently. Conventional photocatalysts include titanium dioxide, zinc oxide, and cadmium sulfide and many other oxide sulfide semiconductors, but these catalysts are basically limited in their use by low light utilization and high lightinduced electron-hole complexation rates. [14,15] As functional nanomaterials with excellent optical and electronic properties such as efficient light harvesting, extraordinary UCPL, and excellent photoinduced electron transfer, CDs combined with photocatalysts can broaden the photoresponsive region and improve the separation ratio of photoinduced carriers. [16,17] CDs are therefore considered to be an effective component for the construction of high-performance photocatalysts, and this area has been extensively investigated by researchers. CDs/Bi 2 MoO 6 composite photocatalysts were prepared by Samanta et al. [18] CDs led to an increase in catalyst light absorption and carrier separation efficiency. Zha et al. [19] synthesized a photocatalyst CDs/BiOCl using Chlorella vulgaris as a carbon source for CDs (CBOC). The introduced CDs broadened the response range of the spectrum, promoted the separation of electron-hole pairs, and enhanced the photocatalytic efficiency.The photocatalytic mechanism of CDs can be the photoexcitation and charge separation of the core carbon. [20] In general, the photocatalytic process based on CDs is divided into the following three processes. First, the absorption of light leads to the generation of electron-hole pairs. Second, the separation and transfer of electron-hole pairs create prerequisites for the reaction. Finally, a redox reaction takes place on the photocatalytic surface. [21] The main factors limiting the photocatalytic process are light absorption and the rate of electron-hole pair complexation, and many approaches have been taken to alleviate these problems.In view of the excellent performance of CDs in photocatalysis, previous reviews have summarized the approaches to improve the photocatalytic efficiency of CDs and the applications of CDs-based photocatalytic materials. [22][23][24][25][26] However, this thesis provides a review of the recent literature in this With their unique optical and electronic properties, carbon dots (CDs) are showing great momentum in many fields such as biosensing, imaging, drug delivery, and photocatalysis. Due to their efficient light harvesting, extraordinary upconversion photoluminescence, and excellent photoinduced electron transfer capabilities, the combination of CDs with photocatalytic materials will promote light absorption resulting in increased generation...
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