Recent progress of metal halide perovskite materials in heterogeneous photocatalytic organic reactions.

Photocatalytic technology is widely regarded as an important way to utilize solar energy and achieve carbon neutrality, which has attracted considerable attentions in various fields over the past decades. Metal halide perovskites (MHPs) are recognized as "superstar" materials due to their exceptional photoelectric properties, readily accessible and tunable structure, which made them intensively studied in solar cells, light-emitting diodes, and solar energy conversion fields. Since 2018, increased attention has been focused on applying the MHPs as a heterogeneous visible light photocatalyst in catalyzing organic synthesis reactions. In this review, we present an overview of photocatalytic technology and principles of heterogeneous photocatalysis before delving into the structural characteristics, stability, and classifications of MHPs. We then focus on recent developments of MHPs in photocatalyzing various organic synthesis reactions, such as oxidation, cyclization, C-C coupling etc., based on their classifications and reported reaction types. Finally, we discuss the main limitations and prospects regarding the application of metal halide perovskites in organic synthesis.

Visible-Light-Induced C-H Cyanoalkylation of Azauracils with Cycloketone Oxime Esters via Catalytic EDA Complex.

Photoexcitation electron donor-acceptor (EDA) complexes provide an effective approach to produce radicals under mild conditions, while the catalytic version of EDA complex photoactivation remains scarce. Herein, we report a visible-light-induced organophotocatalytic pathway for the cyanoalkylation of azauracils using inexpensive and readily available 1,4-diazabicyclo[2.2.2]octane (DABCO) as a catalytic electron donor. This synthetic method exhibits exceptional compatibility with various functional groups and presents 34 examples in high yields. The efficient cyanoalkylation offers an environmentally friendly and sustainable route toward enhancing the structural and functional diversity of azauracils.

Lead-free Cs2AgBiBr6 double perovskite microcrystals for effective visible-light photocatalytic thio/selenocyanation.

Lead-free perovskite microcrystals (MCs) have been regarded as promising potential photocatalysts, owing to their high molar extinction coefficient, low economic cost, adjustable light absorption range, and ample surface-active sites. Herein, C-3 thio/selenocyanation of indoles is demonstrated in high selectivity and yield by using lead-free double perovskite Cs2AgBiBr6 MCs under visible light irradiation. Moreover, the photocatalyst can be recycled at least 5 times without a significant decrease in catalytic activity.

Solvent-regulated self-assembled carbon nitride for photocatalytic reduction of U(VI) in water.

Manufacturing high-performance and reusable materials from radioactive uranium-containing wastewater remains a significant challenge. Herein, a supramolecular self-assembly strategy was proposed, using melamine and cyanuric acid as precursors and using intermolecular hydrogen bond force to form carbon nitride (CN-D) in different solvents through a single thermal polymerization strategy. Supramolecular self-assembly method is a promising strategy to synthesize a novel carbon nitride with molecular regulatory properties. In addition, 98% of U(VI) in wastewater can be removed by using CN-D for 60 min under visible light. After five cycles of recycling, more than 95% of U(VI) can still be reduced, indicating that it has good recyclability and reusability. This study not only provides an efficient photocatalytic method of uranium reduction, but also provides a new method for self-assembly synthesis.

Visible-light-driven EDA complex-promoted cascade cyclization to construct 4-cyanoalkyl isoquinoline-1,3-diones.

Visible-light-induced EDA complex-promoted ring-opening of cycloketone oxime esters to synthesise various cyanoalkylated products with N-methacryloyl benzamides was developed. Various radical receptors were compatible with the current reaction system to furnish diverse heterocyclic compounds. Mechanistic analysis shows that the formation of an EDA complex was crucial to the photocatalytic strategy. Importantly, 4-cyanoalkyl isoquinoline-1,3-diones were obtained in high yields by using a catalytic amount of 1,4-diazabicyclo[2.2.2]octane (DABCO) through prolonging the reaction time, which provided a practical approach to give a variety of isoquinoline-1,3-dione derivatives.

Neutral nickel-catalyzed dehydrosulfonylation of unactivated allylic alcohols under mild conditions.

Allyl sulfones are important sulfur-containing compounds that have widespread applications in organic synthesis, medicinal chemistry and materials science. Herein, nickel-catalysed dehydrosulfonylation of unactivated allyl alcohols with aryl sulfonyl hydrazides without additional active agents under mild conditions was developed. A variety of functional allyl sulfones could be efficiently synthesized in the presence of air-stable Ni(acac)2 as the catalyst and 1,1'-bis(diphenylphosphino)ferrocene (DPPF) as the ligand.

Visible-light-induced decarboxylative cascade cyclization of acryloylbenzamides with N-hydroxyphthalimide esters via EDA complexes.

A visible-light-induced decarboxylative cascade reaction of acryloylbenzamides with alkyl N-hydroxyphthalimide (NHP) esters for the synthesis of various 4-alkyl isoquinolinediones mediated by triphenylphosphine (PPh3) and sodium iodide (NaI) was developed. This operationally simple protocol proceeded via the photoactivation of electron donor-acceptor (EDA) complexes between N-hydroxyphthalimide esters and NaI/PPh3, resulting in multiple carbon-carbon bond formations without the use of precious metal complexes or synthetically elaborate organic dyes, which provided an alternative practical approach to synthesize diverse isoquinoline-1,3(2H,4H)-dione derivatives.

Visible light-mediated synthesis of quinazolinones from benzyl bromides and 2-aminobenzamides without using any photocatalyst or additive.

This paper reports a novel method for the visible-light-mediated synthesis of quinazolinones from the reaction of benzyl bromides with 2-aminobenzamides. The reaction proceeded efficiently at room temperature upon irradiation with an 18 W blue light-emitting diode in air without photocatalysts or additives. By varying the solvent type, substrate molar ratio, and reaction time, the optimal reaction conditions, including the use of methanol solvent, room temperature, and reaction time of 28 h, were identified. Under these conditions, various quinazolinones were obtained using 18 substrates, with the highest yield of 93%. To determine the industrial value of the proposed method, a scale-up reaction was performed and 80% product yield was achieved. Mechanistic studies revealed that the reaction likely proceeded via a radical pathway and that the hydrogen bromide by-product generated during the first step of the reaction of benzyl bromide with 2-aminobenzamide promoted the subsequent step.

Visible-light-enabled cascade cross-dehydrogenative-coupling/cyclization to construct α-chromone substituted α-amino acid derivatives.

Organophotocatalytic cascade cross-dehydrogenative-coupling/cyclization reaction of o-hydroxyarylenaminones with α-amino acid derivatives for the construction of α-chromone substituted α-amino acid derivatives was developed. Various N-arylglycine esters, amides and dipeptides underwent the cascade cyclization reaction well with o-hydroxyarylenaminones to afford the corresponding 3-aminoalkyl chromones in good to excellent yields. This approach consists of visible-light-promoted oxidation of α-amino acid derivatives, the Mannich reaction, and intramolecular nucleophilic cyclization under acidic conditions, and features a wide reaction scope, a simple operation and mild reaction conditions, which may have the potential to be used for the synthesis of bioactive molecules.

Visible-Light Photocatalytic Highly Selective Oxidation of Alcohols into Carbonyl Compounds by CsPbBr3 Perovskite.

Conversion of alcohols into corresponding carbonyl compounds through an oxidation reaction with high conversion and selectivity simultaneously under mild conditions still remains a great challenge. Herein, a cost-effective and highly efficient photocatalytic protocol for selective oxidation of alcohols was developed using CsPbBr3 perovskite as a heterogeneous photocatalyst, which afforded aldehydes/ketones exclusively with a yield of 99% at ambient temperature under an air atmosphere. Moreover, the photocatalyst can be recycled at least 5 times without a significant decrease in catalytic activity. The detailed reaction mechanism was investigated by a series of quenching experiments, including Stern-Volmer experiments and electron paramagnetic resonance spectroscopy analysis as well as DFT calculations.

Visible-Light Photocatalytic Aerobic C═C Bond Cleavage of Alkenes to Carbonyls by CsPbBr3 Nanocrystals.

Herein, we reported a facile and readily accessible visible-light-driven photocatalytic protocol to induce oxidative cleavage of C═C bonds to corresponding carbonyls using CsPbBr3 nanocrystals as photocatalysts. This catalytic system was applicable to a wide range of terminal and internal alkenes. Detailed mechanism studies indicated that a single-electron transfer (SET) process was involved in this transformation, wherein the superoxide radical (O2•-) and photogenerated holes played crucial roles. Additionally, DFT calculations revealed that the reaction was initiated by the addition of O2•- to the terminal carbon atom of the C═C bond and completed by releasing one molecular formaldehyde by the formed [2 + 2] intermediate; the latter conversion was a rate-determining process.

Synthesis of fused quinazolinones via visible light induced cyclization of 2-aminobenzaldehydes with tetrahydroisoquinolines.

This study reports a novel method for the synthesis of fused quinazolinones by visible-light-induced cyclization of 2-aminobenzaldehydes and tetrahydroisoquinolines. The reaction is easily carried out by irradiation with a blue LED in the presence of 9-fluorenone and air. A broad substrate scope with good tolerance of functionalities was observed under the optimized reaction conditions. Moreover, using 2-aminophenone as the substrate and under similar reaction conditions, the same product was obtained when a carbon was removed. The bio-active naturally occurring alkaloid rutaecarpine could be obtained by this strategy. The success of the reaction on the gram-scale and the further transformation of the substrate demonstrated the synthetic practicability of this reaction.

Nickel-catalyzed sulfonylative coupling of 2-chlorobenzothiazoles with sulfinates at room temperature.

An efficient nickel-catalyzed cross-coupling for the synthesis of 2-sulfonylthiazoles from readily available 2-chlorobenzothiazoles and sodium sulfinates has been developed. A variety of 2-chlorobenzothiazoles and sulfinates having a diverse range of substitution patterns can undergo the coupling process successfully at room temperature. Avoiding the use of precious catalysts and sensitive ligands, moderate to excellent yields of various 2-sulfonylthiazoles were observed.

Fast quinazolinone synthesis by combining enzymatic catalysis and photocatalysis.

A fast and highly efficient method for the synthesis of functionalized quinazolinones by combining enzymatic catalysis and photocatalysis is reported. The α-Chymotrypsin catalyzed the cyclization of aldehyde and 2-aminobenzamide, which was subsequently followed by White LED-induced oxidation of 2-phenyl-2, 3-dihydroquinazolin-4(1H)-one to obtain quinazolinone. The reaction process was highly efficient with a reaction yield of 99% in just 2 h, and a wide range of quinazolinones could be synthesized. Furthermore, the plausible mechanism was investigated by control experiments and DFT calculations. This protocol provides an alternative synthetic route for the preparation of quinazolinone derivatives.

MIL-100(Fe)/g-C3N4 composites with enhanced photocatalytic activity for UO22+ reduction under visible light.

As a clean energy source, nuclear energy can gradually replace traditional fossil energy sources, and is an important means to achieve the "double carbon goal". Uranium-containing wastewater is inevitable in the development of nuclear energy. The composites MIL/CNx of MOF material MIL-100(Fe) and carbon nitride (CN) were obtained by a simple solvo-thermal method using iron nitrate, homophthalic acid and CN. The material MIL-100(Fe) with high specific surface area was compounded with CN to increase the in-plane adsorption sites, which could adsorb 30% of uranium in solution during the dark reaction. The close interfacial contact of the two materials effectively inhibited the complexation of photo-generated electrons and holes and promotes electron migration. These two synergistic effects improved their overall photocatalytic reduction capacity, which could reduce 97% of UO22+ in solution in 20 min. The UO22+ removal efficiency of MIL/CN0.1 was 2.3 and 1.6 times higher than that of CN and MIL-100(Fe), respectively. In addition, MIL/CN0.1 was stable in reducing uranium during the five cycles of the experiment.

Combining Enzyme and Photoredox Catalysis for the Construction of 3-Aminoalkyl Chromones.

Herein, we reported a practical and efficient strategy combining photoredox and enzyme catalysis for the construction of 3-aminoalkyl chromones from o-hydroxyaryl enaminones and N-arylglycine esters. A variety of 3-aminoalkyl chromones were synthesized with good yields under mild conditions in one pot. This synthetic protocol consists of sequential enzymatic hydrolysis and photoredox decarboxylation of N-arylglycine esters, oxidation of aminoalkyl radicals, Mannich reaction, and intramolecular nucleophilic cyclization, which affords a convenient pathway for the preparation of various 3-substituted chromones.

Photocatalyst-free Light-driven Dehydrogenation of Alcohols into Carbonyl Compounds under Mild Conditions.

Herein, we reported a photocatalyst-free, facile and eco-friendly method for conducting dehydrogenation of alcohols to corresponding aldehydes or ketones with high selectivity under mild conditions. The methodology exhibited outstanding tolerance with electron-donating and electron-withdrawing groups and afforded series of aldehydes or ketones in considerable yields. Furthermore, the plausible mechanism was investigated by control experiments and DFT calculations. The advantages of readily accessible, atomic economy and green reaction conditions for the present method will endow it with prospective application in chemical synthesis.

Copper-assisted preparation of pyridinyl sulfonate esters from hydroxypyridines and sodium sulfinates.

An efficient and powerful copper-assisted method for the effective conversion of a broad range of hydroxypyridines and sodium sulfinates into their corresponding pyridinyl tosylates was developed. Key features of this base- and ligand-free protocol include using the cheap and readily available CuBr2 as a medium and the use of sodium sulfinates as formal sulfonylation reagents. A variety of functional pyridinyl tosylates could be formed with good yields, which can easily be converted into C-C and C-N bond-containing compounds.

Synthesis of quinazoline by decarboxylation of 2-aminobenzylamine and α-keto acid under visible light catalysis.

Quinazoline compounds demonstrate a variety of physiological and pharmacological activities. However, the most common syntheses require large quantities of oxidants, high temperature, and other extreme conditions. In this study, quinazoline compounds were synthesized from the condensation of α-keto acid and 2-aminobenzylamine and then decarboxylation under blue LED irradiation at room temperature without transition metal catalysts or additives. Therefore, we demonstrated that by using α-keto acid as the acyl source, decarboxylation can be realized under blue LED without oxidants, in a simple, mild, and environmentally friendly process.

Base-promoted synthesis of diarylsulfones from sulfonyl hydrazines and diaryliodonium salts.

An efficient and concise method for the synthesis of diverse substituted sulfones was developed with high selectivity. Using n-PrOH as the solvent, diaryl sulfones are formed even on a gram scale via metal-free coupling from sulfonyl hydrazines with symmetrical or unsymmetrical diaryliodonium salts.