Metal-free aminofluorination of α-diazo 2H-benzopyran-4-one: convenient access to ß-fluoramides.

We have developed a convenient synthesis of a series of ß-fluoramides in 65% yield. The process involved a tandem fluorination/Ritter reaction to synthesize ß-fluoramides using α-diazo 2H-benzopyran-4-one compounds. Selectfluor was used as the electrophilic fluoride source in acetonitrile to build the ß-fluorinated quaternary carbon center and amide derivatives of 2H-benzopyran-4-one in one step. The products N-(2-(2-fluoro-2,3-dihydro-3-oxobenzofuran-2-yl)propan-2-yl)acetamides were a series of bifunctional compounds with a 2-fluoro-2,3-dihydro-3-oxobenzofuran motif and amide groups.

Recent developments in photocatalytic production of hydrogen peroxide.

Hydrogen peroxide (H2O2), an environmentally friendly strong oxidant and energy carrier, has attracted widespread attention in photocatalysis. Artificial photosynthesis of H2O2 using water and oxygen as raw materials, solar energy as an energy source, and semiconductor materials as catalysts is considered a promising technology. In the past few decades, encouraging progress has been made in the photocatalytic production of H2O2. Therefore, we summarize the research achievements in this field in recent years. This review first briefly introduces the reaction pathway, detection techniques and evaluation metrics. Then, the recent advances in photocatalysts are highlighted. Furthermore, the existing challenges and possible solutions in this field are presented. At last, we look forward to the future development direction of this field. This review provides valuable insights and guidance for efficient photocatalytic H2O2 production.

Polyoxometalates tailoring of frustrated Lewis pairs on Ce-doped Bi2O3 for boosting photocatalytic CO2 reduction.

Constructing frustrated Lewis pairs (FLPs) on catalysts will provide catalytic sites to activate CO2 and boost photocatalytic CO2 reduction. Herein, a Ce-doped bismuth oxide (CeBiOX) with FLPs was designed by loading [(α-SbW9O33)2Cu3(H2O)3]12- (Cu3) via strong electrostatic interactions to create oxygen vacancies (OVs). Detailed experiments and measurements showed that Cu3 could regulate the FLPs and optimize the band structure of CeBiOX to boost photocatalytic CO2 reduction. In particular, the Cu3/CeBiOX composite exhibited the highest yields of CO (42.85 µmoL g-1) and CH4 (13.23 µmoL g-1), being 6.6 and 3.3 times, and 4.9 and 6.3 times higher than those of pristine Bi2O3 and CeBiOX, respectively. This work provides a significant and mild approach to obtaining advanced catalysts with tuneable FLPs for more fields.

A concise synthesis of L-pyrrolysine.

Organocatalysis: A concise synthesis of L-pyrrolysine has been accomplished in six steps from simple starting materials. The facile synthetic strategy relies on an organocatalytic Michael addition, an efficient amide coupling, and a challenging method for the imine-bond construction.

Efficient photocatalytic hydrogen production over ZnIn2S4 by producing sulfur vacancies and coupling with nickel-based polyoxometalate.

A composite catalytic system using sulfur-vacancy-containing ZnIn2S4-Sv as a light-harvesting material and nickel-based polyoxometalate Na6K4[Ni4(H2O)2(PW9O34)2] (Ni4POM) as a co-catalyst was developed. The Ni4POM/ZnIn2S4-Sv composite gave a good hydrogen production rate of 337.5 µmol h-1, a value 11.8 times higher than that of ZnIn2S4-Sv. The direction of electron transfer, from ZnIn2S4-Sv to Ni4POM, was verified using surface photovoltage spectra.

Boosting photocatalytic conversion of formic acid to CO over P-doped CdS.

In this work, NaH2PO2, Na2S2O3 and CdCl2 were used to synthesize P-doped CdS samples for the photocatalytic decomposition of formic acid to CO reaction. The CO production rates and selectivity of P-doped CdS are as high as 24.5 mmol g-1 h-1 and 92.4%, in which the rate is 7 times higher than that of the pure CdS. Multiple characterizations show that the P-doping increases the specific surface area, widens the band gap and shifts the energy band position of CdS, resulting in enhanced photocatalytic activity.

Mononuclear ruthenium (II) complex covalently anchored on melem and g-C3N4 as efficient heterogeneous catalysts for chemical water oxidation.

Ru-melem and Ru-C3N4 were synthesized by a simple and facile strategy to construct a novel covalently anchoring by introducing easily synthesized amide bond as a bridge connecting the Ru-terpy and melem or g-C3N4, respectively. The covalent anchoring of Ru complex on melem or C3N4 not only makes these materials exhibit water oxidation activity under CeIV-driven (CeIV = Ce(NH4)2(NO3)6) reaction condition, but also makes the obtained heterogeneous catalysts show higher catalytic activity than the corresponding homogeneous catalysts, which reveals that the covalent anchoring strategy of Ru complex is beneficial to improve the catalytic activity of homogeneous Ru catalysts. The synthetic method of hybrid catalysts offers an insightful strategy for enhancing water oxidation activity of molecular catalysts.

Fusogenic metallosupramolecular brush vesicles.

The electrostatic combination of a cationic metallosupramolecular polyelectrolyte (Fe-MSP) with sulfonate-terminated polymers leads to the formation of metallosupramolecular brushes (MSBs). The resulting MSBs can self-assemble into vesicular structures in chloroform/methanol (v/v = 1:1) mixture solvents. The rigid-rod Fe-MSP chain has to bend for the formation of the vesicles, which accompanies the presence of a lateral tension and thus induces a spontaneous vesicle fusion with an hour-scale fusion time. For this much longer fusion process, the arrow-like protrusion, stalk-like intermediate, and hemifusion diaphragm are clearly observed by transmission electron microscopy. The complete fusion into larger vesicles significantly releases the lateral tension.

Enhanced photocatalytic activity of BiVO4 coupled with iron-based complexes for water oxidation under visible light irradiation.

[Fe2(TPA)2(µ-O)Cl2]2+ (TPA = tris(2-pyridylmethyl)amine) was investigated as a pre-catalyst, and greatly enhanced the photocatalytic water oxidation activity of BiVO4. An extremely high oxygen yield of 99.1% and apparent quantum yield of 44.3% were obtained in the BiVO4-NaIO3 photocatalytic water oxidation system.

A simple biomimetic synthesis of dl-chamaejasmine, a unique 3,3'-biflavanone.

[Reaction: see text] The first chemical synthesis of dl-chamaejasmine (1), a structurally unique 3,3'-biflavanone natural product, was achieved as shown above, by a two-step sequence starting from trimethyl ether derivatives of 3-iodonaringenin (cis + trans) involving (i) metallic lanthanum-mediated reductive dimerization in refluxing THF and (ii) global demethylation with BBr3 in CH2Cl2. This synthesis represents a generally applicable biomimetic (reductive) radical dimerization approach to the 3,3'-biflavonoids.

Efficient light-driven water oxidation catalyzed by a mononuclear cobalt(III) complex.

A mononuclear Co complex, [Co(III)(DPK·OH)2]Cl (DPK = di(2-pyridyl)ketone), was synthesized and reported as a stable catalyst in visible light-driven water oxidation. The optimum turnover number (TON) of complex 1 is 1610, which, to the best of our knowledge, is the largest TON among metal-organic complexes for photocatalytic water oxidation.

Efficient photocatalytic water oxidation catalyzed by polyoxometalate [Fe11(H2O)14(OH)2(W3O10)2(α-SbW9O33)6](27-) based on abundant metals.

An eleven iron-containing nanoscale inorganic polyanionic oxide cluster was reported as the first example for exceptional photocatalytic water oxidation. Under optimal conditions, a remarkable turn-over number (TON) of 1815 ± 50 and a turn-over frequency (TOF(initial)) of 6.3 s(-1) over were achieved for water oxidation.

An efficient oxygen evolving catalyst based on a µ-O diiron coordination complex.

A family of oxygen evolving catalysts was investigated, which was based on the most desired first-row transition metal iron. Among them, the highest turnover number of 2380 was obtained in acetate buffer at pH 4.5 with [(TPA)2Fe2(µ-O)(µ-OAc)](3+).

One-pot novel regioselective cycloisomerization synthesis of 2-substituted or 3-substituted 4H-furo[3,2-c]chromene through the intermediate cyclopropenes of 3-diazochroman-4-one and phenylacetylene.

A new class of cyclopropenes containing a chroman-4-one motif were synthesized using 3-diazochroman-4-one and phenylacetylene with rhodium(II) catalyst and followed by cycloisomerization to give 2-substituted or 3-substituted 4H-furo[3,2-c]chromene, respectively. Using BF3·Et2O as catalyst, 2-substituted 4H-furo[3,2-c]chromene was exclusively obtained in 70% yield. Using Cu(OTf)2 as catalyst, 3-substituted 4H-furo[3,2-c]chromene was obtained in 95% yield with 98:2 regioselectivity. A one-pot cascade addition-cycloisomerization process was also developed with no need to isolate cyclopropenes of chroman-4-one intermediates.

A mononuclear cobalt complex with an organic ligand acting as a precatalyst for efficient visible light-driven water oxidation.

N,N'-Bis(salicylidene)ethylenediaminecobalt(II) (1) has been investigated as a highly efficient water oxidation precatalyst with a TON of 854 at pH = 9.0, using [Ru(bpy)3](ClO4)2 as a photosensitizer and Na2S2O8 as a sacrificial electron acceptor.

Magnetically separable polyoxometalate catalyst for the oxidation of dibenzothiophene with H2O2.

Two types of polyoxometalate-functionalized magnetic nanoparticles catalysts consisting of H(3)PW(12)O(40) supported on surface-modified Fe(3)O(4) magnetite nanoparticles were prepared using an easy synthetic route and successfully applied for the oxidation of dibenzothiophene. The magnetic catalysts showed a catalytic performance in the oxidation of dibenzothiophene in acetonitrile with hydrogen peroxide, and high conversions were obtained. The catalysts could be easily separated from the reaction solution by applying an external magnetic field and recycled several times.

A novel formal total synthesis of cephalotaxine.

A formal total synthesis of cephalotaxine (CET), the parent structure of antileukemia Cephalotaxus alkaloids, was achieved through a novel synthesis of the pentacyclic amino enone 4 by a rapid annulation of readily available beta-(3,4-methylenedioxy)phenethylamine (2), delta-valerolactone, and bromoacetone.

An alternative synthesis of Dolby-Weinreb enamine en route to cephalotaxine.

A novel alternative synthesis of the Dolby-Weinreb enamine (2) was achieved from readily available amino dione 6 by a mild transannular Clemmensen-Clemo-Prelog-Leonard reductive rearrangement, which thus constitutes a formal total synthesis of cephalotaxine.