All current industrial carbonylation processes rely on highly toxic and flammable carbon monoxide. Since these properties impede the wider use of carbonylation reactions in industry and academia, performing carbonylations with CO surrogates is highly desired and will contribute to further advances in sustainable chemistry. This Minireview summarizes the carbonylations of alkenes using different CO surrogates.

Not just scratching the surface: Covalently attached monolayers on oxide surfaces are reviewed with an eye to improved robustness, increased functionalization, understanding structural details, and the resulting potential for applications. Such monolayers, provided they are robust enough, provide a way of improving the properties of the bulk oxide material.

A good Al-rounder: Al ions can induce the formation of backbone ring structures in a wide range of peptides, including neurodegenerative disease related motifs. The rings are formed by the Al ion forming bonds simultaneously with the amide nitrogen and carbonyl oxygen atoms on the peptide backbone, which destabilizes the protein and results in irreversible denaturation.

Nature as role model: Comparable to quinones that extract electrons from chlorophyll in the natural photosystem II, polydopamine (PDA) accelerates proton-coupled electron transfer and enables efficient charge separation of [Ru(bpy)₃]²⁺. The introduction of PDA as an electron gate as well as a versatile adhesive significantly increases the efficiency of photochemical water oxidation.

Nanobridging is obtained by spreading a drop of aqueous nanoparticle solution on a wound edge and bringing edges into contact. In less than a minute, a strong closure and hemostasis can be achieved even within a wet and dynamic environment. Nanoparticle solutions can be also used to attach medical devices to organs.

On the same page: The patterned deposition of Teflon on paper creates barriers resistant to organic solvents. The solvents confined by the pattern flow through the paper at a controlled flow-rate, which permits the flow-through synthesis of 96 peptides in parallel on one sheet of paper. The resulting peptide arrays can be used to perform cell-based assays and discover 3D materials that support cell adhesion and growth.

By taking advantage of the singlet fission process highly efficient phosphorescent emitters based on metal- and heavy atom-free boron compounds were synthesized. The combination of a suitable molecular scaffold and appropriate electronic properties of the substituents was utilized to tailor the phosphorescence emission properties in solution, neat solid, and in doped PMMA films.

A general scheme: A highly enantioselective copper-catalyzed carboetherification of 4-pentenols has been developed. Both intramolecular (formal CH functionalization) and intermolecular (net alkyl Heck-type coupling; see scheme) CC bond formation can occur, thus forming a range of chiral functionalized tetrahydrofurans. DFT transition-state calculations provide a rationale for the observed asymmetric induction.

An iron boost: High-spin iron(III) iodosylarene complexes bearing an N-methylated cyclam ligand are prepared. The nonheme high-spin iron(III) iodosylarene intermediates are highly reactive oxidants capable of activating strong CH bonds of alkanes. The electrophilic character of the iron(III) iodosylarene complexes is demonstrated in sulfoxidation reactions.

Triple: The distinguishing piperidine-metacyclophane framework of the Lythraceum alkaloid lythanidine was formed by ring-closing alkyne metathesis (RCAM) of a propargylic alcohol derivative followed by redox isomerization and a proton-catalyzed transannular aza-Michael addition as the key steps. This straightforward approach illustrates the enabling power of catalytic alkyne chemistry for target-oriented synthesis.

Coupling DFT simulations, microkinetic modeling and synthesis tools allowed the development of supported CuCo bimetallic nanoparticles as highly efficient catalysts for the selective conversion of synthesis gas (CO+H₂) into ethanol and longer-chain alcohols. As predicted by theory, maximizing the contribution from mixed Cu–Co sites, while preventing Cu phase segregation, results in superior yields to high alcohols.

Lighting up: Butterfly-shaped benzophenone derivatives with small excited singlet–triplet energy gaps are demonstrated to exhibit efficient full-color delayed fluorescence. Organic light-emitting diodes employing these benzophenones as emitters can generate electroluminescence across most of the color gamut range, including white.

Four phases of Mo-C, including γ-MoC which was stabilized for the first time as a nanomaterial, were synthesized and investigated for their catalytic activity and stability in the hydrogen evolution reaction (HER). X-ray photoelectron spectroscopy and valence band studies were also conducted for the first time on γ-MoC.

Counting mers: Poly(ethylene oxide) (PEO) is one of the most widely used polymers, but polydispersity hinders establishing its structure–property relationships. A synthetic procedure that provides PEO with an unprecedented low level of dispersity is reported. In addition a mass spectrometric method is presented to measure such low dispersity.

Desirable tailoring: Hollow polymer nanocapsules (PNs) made of cucurbit[6]uril (CB) serve as a versatile platform since various metal nanoparticles (NPs) can be introduced on the surface. They allow for a controlled synthesis, prevent self-aggregation, and provide high stability and dispersibility. Pd@CB-PNs show outstanding properties as heterogeneous catalysts in CC and CN bond-forming reactions in water.

Always the sun? Biosynthetic considerations guided the first total synthesis of dictazole B. Furthermore, insights into the biosynthetic pathway towards the aplysinopsin family were gained, and an easy access to challenging cyclobutane alkaloids of marine origin, which are often postulated to be biosynthetic precursors of more complex structures, was developed.

Interesting faces with chiseled features: No longer limited to nanoribbons and smooth nanoplates, Bi₂Se₃ nanostructures in the form of spiral-type nanoplates with a bipyramid-like shape characterized by two sets of centrosymmetric helical fringes on the top and bottom faces were formed by a bidirectional growth process. Other evidence for the unique structure and growth mode include herringbone contours, spiral arms, and hollow cores (see picture).

Changing the landscape: A cyclic tetramer of pyrene, [4]cyclo-2,7-pyrenylene ([4]CPY), was synthesized by the platinum-mediated cyclotetramerization and subsequent dehydrogenation. DFT calculations and electrochemical analyses showed that the electronic structure of [4]CPY was completely altered from that of pyrene and linear oligopyrenes. The results clearly show there is modulation of the topology of molecular orbitals upon formation of a cyclic structure.

Four roads diverged: A zinc bromide complex, generated by the sequential reaction of nitriles with a Reformatsky reagent and 1-alkynes, is used as an intermediate for divergent palladium-catalyzed reactions. The reaction pathway depends on the choice of reaction solvents and palladium catalysts. The method provides a simple and efficient approach to four different frameworks starting from readily available nitriles.

A Pd complex: An efficient method for the enantioselective construction of tertiary vinylglycols by the title reaction was developed. The palladium complex generated from [Pd₂(dba)₃]⋅CHCl₃ and L catalyzes the cycloaddition under mild reaction conditions, thus converting racemic 1 into the corresponding 1,3-dioxolanes 2 in high yields with good to excellent enantioselectivities. dba=dibenzylideneacetone.

Rational splitting of the dual-binding properties of a natural product delivers two mechanistically different ligands, which selectively target opposite sides of a dynamic protein interface (see picture; AF2=activation function 2). This work highlights the value of screening natural products against transient protein complexes.

Visualizing toxin trafficking: Coupling the genetic-code expansion strategy with bioorthogonal reactions allowed site-specific fluorescent labeling of anthrax lethal factor (LF) with little perturbation to its native structure and function. Time-lapse visualization of the endocytic trafficking of a precisely labeled LF revealed molecular details underlying its virulence mechanism inside host cells. PA=protective antigen.

A 3D microporous conductive polymer has been achieved in the electrochemical synthesis of a porous polyaniline network with a MOF thin film. The prepared microporous polyaniline with well-defined uniform micropores of 0.84 nm exhibits a high BET surface area of 986 m² g⁻¹ and a high electric conductivity of 0.125 S cm⁻¹ when doped with I₂.

Catching bubbles: Tetrazine-functionalized microbubbles were prepared for use as ultrasound contrast agents, and shown to selectively localize on cells labeled with a TCO-derivatized antibody against VEGFR2. This capture approach based on labeling and bioorthogonal chemistry was validated in a flow-chamber assay and in vivo through ultrasound imaging of VEGFR2-positive and VEGFR2-negative murine tumor models. TCO=trans-cyclooctene.

Diffusion-ordered multidimensional NMR spectroscopy is a valuable technique for the analysis of complex mixtures, but the sampling of a multidimensional signal can be very time-consuming. Various sparse sampling techniques have been proposed to accelerate the measurement, but they have always been limited to frequency dimensions of NMR spectra. It is now revealed how sparse sampling can be extended to diffusion dimensions.

Outside the box: Carbonyl–ene reactions of 2,3-diketoesters, catalyzed by [Cu{(S,S)-tBu-box}](SbF₆)₂ [box=bis(oxazoline)], generate chiral α-functionalized α-hydroxy-β-ketoesters in up to 94 % yield and 97 % ee. The 2,3-diketoesters are conveniently accessed from the corresponding α-diazo-β-ketoester, and a catalyst loading as low as 1.0 mol % can be used.

Teacher′s PET: The title reaction delivers excellent yields of the desired alkyl fluorides by using potassium fluoride as a fluoride source in the presence of the copper catalyst [IPrCuOTf]. This procedure is potentially suited for the preparation of ¹⁸F-labeled PET probes. IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, Tf=trifluoromethanesulfonyl.

Blue (light) is green: The efficient light-induced atom-economical alkane dehydrogenation of various linear and cyclic alkanes (including shale gas constituents and liquid organic hydrogen carriers) was accomplished using trans-[Rh(PMe₃)₂(CO)Cl] as a catalyst in the presence of a specific nitrogenous additive. It provides a benign alternative to the direct use of alkanes as olefin feedstocks.

Boosting the PEPPSI: A sequential enhancement of the activity of the PEPPSI NHC-based palladium pre-catalyst in the Buchwald–Hartwig amination was obtained by a rational modification of its standard N-heterocyclic carbene (IMes or IPr), consisting of a “simple” incorporation of one, and then two, dimethylamino groups as substituents. These results highlight the valuable benefits of NHC-skeleton decoration in C–N cross-coupling.

Learning from nature: An amino acid-based outer coordination sphere results in the homogeneous [Ni(P^Cy₂N^Arg₂)]⁸⁺ complex that can electrochemically oxidize H₂ in water with a turnover frequency of 210 s⁻¹ at acidic pH. The outer coordination sphere improves the H₂ addition and H⁺ movement from the active center.

Oxygen leads the way: [Pd(P(Ar)(tBu)₂)₂] (Ar=naphthyl) undergoes a reaction with molecular oxygen in which CH and OO bonds are cleaved. Observation of the reaction at low temperature suggests the initial formation of a superoxo complex, which then generates a peroxo complex prior to the CH activation step. The transition state for an energetically viable CH activation across a Pdperoxo bond was located computationally.

Not ones to laze about on the lawn, nitrogen-doped graphene/carbon-nanotube (CNT) hybrids showed high electrocatalytic activity for a series of important electrochemical reactions as a result of nitrogen doping and their unique structure with the graphene nanosheets entrapped in the inner void of the CNTs. The hybrids were prepared by a facile low-cost method from solid-phase sources with high efficiency.

Peptides and proteins can be cleaved selectively at serine residues under mild (room temperature, near neutral pH value) aerobic conditions by a water-soluble copper–organoradical conjugate. The method is applicable to the site-selective cleavage of polypeptides that possess various functional groups, D-amino acids, or sensitive disulfide pairs. The system was also used for the site-selective cleavage of a native protein comprising more than 70 amino acid residues.

Under construction: A single-step enantioselective access to multicyclic oxoquinoline-type heterocycles is possible. The process takes advantage of the unique reaction patterns of esters under N-heterocyclic carbene (NHC) catalysis. It involves activation of the β-carbon atom of an ester as the key step with a subsequent chemoselective cascade reaction with amino enone substrates. Ts=4-toluenesulfonyl.

Chiral 2,3-allenyl amines with or without (an) additional CC double or triple bond(s) can be prepared through asymmetric Pd-catalyzed amination of allenyl phosphates. Under the optimized conditions, which involve the use of (R)-3,4,5-(MeO)₃-MeOBIPHEP as the ligand and the reaction being performed at 0 °C, the products were obtained with up to 90 % yield and 88–94 % ee.

A fourpeat: The recently discovered 5-hydroxymethylfurfural oxidase (HMFO) was found to perform a quadruple oxidation of [5-(hydroxymethyl)furan-2-yl]methanol (see scheme). The biocatalyst can also be used to convert 5-hydroxymethylfurfural into furan-2,5-dicarboxylic acid, thus providing a biobased platform chemical for the production of polymers. The oxidase acts on alcohol groups only and therefore depends on the hydration of aldehyde groups.

CO for bridged macrolides: An efficient Pd-catalyzed cascade alkoxycarbonylative macrolactonization to synthesize various THP/THF-containing macrolactones in one step from relatively simple alkendiols is possible. Challenging macrolactones involving tertiary alcohols were synthesized smoothly as well. The method was applied to the synthesis of the potent anticancer compound 9-demethylneopeltolide.

Migrating to iridium: Iridium catalysis enables the arylative cyclization of alkynones with arylboronic acids to give complex polycycles with high stereoselectivities. These reactions involve the first reported examples of 1,4-iridium migration.

A copper-catalyzed aerobic oxidative C(CO)C(alkyl) bond cleavage of aryl alkyl ketones for CN bond formation proceeds with high chemoselectivity. A series of acetophenone derivatives as well as more challenging aryl ketones with long-chain alkyl groups could be cleaved efficiently to give the corresponding amides, which are frequently found in biologically active compounds and pharmaceuticals.

Structural revision: A revised configurational assignment for the marine macrolide mandelalide A is proposed and validated by total synthesis. This study is one of several recent examples in a growing list of investigations that correct misassigned structures of natural products by stereocontrolled total synthesis.

Versatile phosphonium salt: The dication [(SIMes)PFPh₂][B(C₆F₅)₄]₂ is prepared by oxidation of an NHC-derived cationic phosphine followed by fluoride abstraction. This species exhibits remarkable Lewis acidity in stoichiometric reactions as well as in Lewis acid catalysis of hydrodefluorination of fluoroalkanes and the hydrosilylation of olefins and acetylenes.

Caught in a trap: A novel strategy for in situ generation of furan-based ortho-quinodimethanes (o-QDMs) using the title reaction was developed. These furan-based o-QDMs were trapped by electron-deficient olefins and alkynes, thus leading to various 2,3-furan-fused carbocycles in good yields with high diastereo- and regioselectivities. EWG=electron-withdrawing group.

β attack! A potassium-bis(trimethylsilyl)amide-mediated cyclopropanation of allyl phosphates with silylboronates has been developed. Unlike the reported copper-catalyzed allylic substitution reactions, the nucleophile selectively attacks at the β-position of the allylic substrates under the present conditions. The reaction mechanism has also been investigated, thus indicating the involvement of a silylpotassium species as the active nucleophilic component.

A couple of carbenes: By utilizing stable carbenes with low-lying LUMOs, coupling with the stable nucleophilic diaminocyclopropenylidene was achieved. This coupling resulted in the formation of two new and rare examples of a bent allene as well as the isolation of the first carbene–carbene heterodimer. Dipp=2,6-iPr₂C₆H₃, Mes=2,4,6-Me₃C₆H₂.

Act(ivat)ing positively: Cationic gold clusters are found to react with molecular oxygen and activate it by forming a superoxide (O₂⁻), as confirmed by vibrational spectroscopy. This process is spontaneous in clusters, which attain a closed shell within the spherical jellium model, whereas other cluster sizes exhibit a self-promoting effect whereby the presence of multiple oxygen ligands is required for activation.

Orthogonal reactivities: Anthraquinone derivatives catalyze the thermal C3- alkylation of indoles with benzylamines in sequence with a visible-light-driven photooxidation/1,2-shift reaction to provide new fluorescent 2,2-disubstituted indoline-3-one derivatives. Quinones function as H₂ shuttles in the indole C3-alkylation with amines and the subsequent photooxidation of the intermediate 3-arylmethyl-1H-indoles is remarkably selective.

Tuning aromaticity: Two stable core-modified rubyrins bearing one (1) and two (2) dithienylethene (DTE) units have been synthesized. Compound 1, with a “closed-form” DTE unit, has a cyclic conjugated system with 26 π-electrons. In contrast, macrocycle 2 containing one “open-form” DTE unit has nonaromatic properties.