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De novo enzyme design has sought to introduce active sites and substrate-binding pockets that are predicted to catalyse a reaction of interest into geometrically compatible native scaffolds1,2, but has been limited by a lack of suitable protein structures and the complexity of native protein sequence–structure relationships. Here we describe a deep-learning-based ‘family-wide hallucination’ approach that generates large numbers of idealized protein structures containing diverse pocket shapes and designed sequences that encode them. We use these scaffolds to design artificial luciferases that selectively catalyse the oxidative chemiluminescence of the synthetic luciferin substrates diphenylterazine3 and 2-deoxycoelenterazine. The designed active sites position an arginine guanidinium group adjacent to an anion that develops during the reaction in a binding pocket with high shape complementarity. For both luciferin substrates, we obtain designed luciferases with high selectivity; the most active of these is a small (13.9 kDa) and thermostable (with a melting temperature higher than 95 °C) enzyme that has a catalytic efficiency on diphenylterazine (kcat/Km = 106 M−1 s−1) comparable to that of native luciferases, but a much higher substrate specificity. The creation of highly active and specific biocatalysts from scratch with broad applications in biomedicine is a key milestone for computational enzyme design, and our approach should enable generation of a wide range of luciferases and other enzymes.

An efficient alkoxyl radical-triggered ring expansion/cross-coupling cascade was developed under cheap metal catalysis. Through the metal-catalyzed radical relay strategy, a wide range of medium-sized lactones (9-11 membered) and macrolactones (12, 13, 15, 18, and 19-membered) were constructed in moderate to good yields, along with diverse functional groups including CN, N3, SCN, and X groups installed concurrently. Density functional theory (DFT) calculations revealed that reductive elimination of the cycloalkyl-Cu(iii) species is a more favorable reaction pathway for the cross-coupling step. Based on the results of experiments and DFT, a Cu(i)/Cu(ii)/Cu(iii) catalytic cycle is proposed for this tandem reaction.

Valence-inverted reactivity (VIR) is discovered here through high-level computations of excited states of Ni(II) complexes that are generated by triplet energy transfer. For example, the so-generated

Lactam rings are found in many biologically active natural products and pharmaceuticals, including important classes of antibiotics. Given their widespread presence in bioactive molecules, methods for the asymmetric synthesis of these molecules, in particular through the selective functionalization of ubiquitous yet unreactive aliphatic C–H bonds, are highly desirable. In this study, we report the development of a novel strategy for the asymmetric synthesis of 4-, 5-, and 6-membered lactams via an unprecedented hemoprotein-catalyzed intramolecular C-H amidation reaction with readily available dioxazolone reagents. Engineered myoglobin variants serve as excellent biocatalysts for this transformation producing an array of β-, γ-, and δ-lactam molecules in high yields, with high enantioselectivity, and on preparative scale. Mechanistic and computational studies elucidate the nature of the C–H amination and enantiodetermining steps in these reactions and provide insights into protein-mediated control of regioselectivity and stereoselectivity. Using this system, it was possible to accomplish the chemoenzymatic total synthesis of an alkaloid natural product and a drug molecule in much fewer steps (7-8 vs. 11-12) than previously possible, which showcases the power of this biosynthetic strategy toward enabling the preparation of complex bioactive molecules.

We report the catalytic generation of a vinyl Pd-oxyallyl that dimerizes regiospecifically to form highly functionalized nonbridged cyclooctanoids. Such compounds are otherwise synthetically challenging, but highly useful in synthesis. This vinyl Pd-oxyallyl species demonstrates both electrophilic and nucleophilic properties. DFT calculations elucidate the mechanism and the origins of the chemoselective cyclooctanoid formation.

We herein report a phosphine-catalyzed (3 + 2) annulation of cyclopropenones with a wide variety of electrophilic π systems, including aldehydes, ketoesters, imines, isocyanates, and carbodiimides, offering products of butenolides, butyrolactams, maleimides, and iminomaleimides, respectively, in high yields with broad substrate scope. An α-ketenyl phosphorous ylide is validated as the key intermediate, which undergoes preferential catalytic cyclization with aldehydes rather than stoichiometric Wittig olefinations. This phosphine-catalyzed activation of cyclopropenones thus supplies a versatile C3 synthon for formal cycloadditon reactions.

We examine the theoretical underpinnings of the seminal discoveries by Reiner Sustmann about the ambiphilic nature of Huisgen's phenyl azide cycloadditions. Density functional calculations with ωB97X-D and B2PLYP-D3 reproduce the experimental data and provide insights into ambiphilic control of reactivity. Distortion/interaction-activation strain and energy decomposition analyses show why Sustmann's use of dipolarophile ionization potential is such a powerful predictor of reactivity. We add to Sustmann's data set several modern distortion-accelerated dipolarophiles used in bioorthogonal chemistry to show how these fit into the orbital energy criteria that are often used to understand cycloaddition reactivity. We show why such a simple indicator of reactivity is a powerful predictor of reaction rates that are actually controlled by a combination of distortion energies, charge transfer, closed-shell repulsion, polarization, and electrostatic effects.

We herein report a phosphine-catalyzed (3 + 2) annulation of cyclopropenones with a wide variety of electrophilic π systems, including aldehydes, ketoesters, imines, isocyanates, and carbodiimides, offering products of butenolides, butyrolactams, maleimides, and iminomaleimides, respectively, in high yields with broad substrate scope. An α-ketenyl phosphorous ylide is validated as the key intermediate, which undergoes preferential catalytic cyclization with aldehydes rather than stoichiometric Wittig olefinations. This phosphine-catalyzed activation of cyclopropenones thus supplies a versatile C

Reactivity of electronically excited base transition metals is an emerging frontier wherein mechanistic understanding is highly desired but mostly lacking. To reveal how C–O bond coupling reductive...

Polycyclic aromatic hydrocarbons are difficult substrates for hydrogenation because of the thermodynamic stability caused by aromaticity. We report here the first chromium- and cobalt-catalyzed, regiocontrolled hydrogenation of polycyclic aromatic hydrocarbons at ambient temperature. These reactions were promoted by low-cost chromium or cobalt salts combined with diimino/carbene ligand and methylmagnesium bromide and are characterized by high regioselectivity and expanded substrate scope that includes tetracene, tetraphene, pentacene, and perylene, which have rarely been reduced. The approach provides a cost-effective catalytic protocol for hydrogenation, is scalable, and can be utilized in the synthesis of tetrabromo- and carboxyl-substituted motifs through functionalization of the hydrogenation product. The systematic theoretical mechanistic modelings suggest that low-valent Cr and Co monohydride species, most likely from zerovalent transition metals, are capable of mediating these hydrogenations of fused PAHs.

Cobalt(III)-promoted C–H activation reactions have witnessed explosive progress in recent few years. However, the roles played by the various spin states of Co(III) center in C–H activation reactivity remain elusive. To resolve this conundrum, herein we go beyond the commonly used DFT methods to explore three typical Co(III)-promoted C–H activation systems. Our high-level coupled cluster modelings demonstrate that multistate reactivity (MSR) involving three spin states operates for C(sp2)–H and C(sp3)–H activations with non-Cp-Co(III) type catalyst, while single-state reactivity (SSR) involving only one singlet spin state operates for C(sp2)–H activation with Cp-Co(III) type catalyst. This ligand-dependent reaction scenario of MSR/SSR reveals the high complexity in mechanisms of Co(III)-promoted C–H activations.

Summary Iron terminal imido species featuring electron-withdrawing N-substituents represent an important category of reactive metal-ligand-multiple-bond intermediates in iron-catalyzed reactions. Knowledge of them is very limited, however, as isolable complexes of this type are hard to access. Here, we report an isolable iron(IV) imido complex with trifluoromethyl on nitrogen, namely [(IPr)Fe(NC(CF3)2Ph)2]. We prepared the complex from the reaction of a low-coordinate iron(0) complex with N3C(CF3)2Ph. It has an S = 1 ground spin-state, long Fe-N(imido) bonds, and bent Fe-N(imido)-C(imido) alignments and can undergo intramolecular C–H bond activation reaction to transform into an iron(II) amido complex. Theoretical study suggests that the C–H bond activation reaction involves hydrogen-atom-abstraction mechanism and that the electron-withdrawing nature of trifluoromethyl group renders the imido ligands in [(IPr)Fe(NC(CF3)2Ph)2] and the transition state of the hydrogen-atom-abstraction step structurally close to each other, resulting in a low activation barrier.

The cleavage of aromatic carbon–nitrogen bonds catalyzed by transition metals is of high synthetic interest because such bonds are common in organic chemistry. However, few metal catalysts can be used to selectively break C(aryl)–N bonds in electronically neutral molecules. We report here the first low-valent, high-spin chromium-catalyzed cleavage of C(aryl)–N bonds in electronically neutral aniline derivatives at room temperature. By using simple and inexpensive chromium(II) chloride as precatalyst, accompanied by an imino auxiliary, the selective arylative and alkylative C–C coupling of C(aryl)–N bonds can be achieved. Crossover experiments indicate that a low-valent chromium species, formed in situ by reduction of CrCl2 with Grignard reagent, is responsible for the catalytic cleavage of C(aryl)–N bonds. DFT calculations show that facile insertion of the C(aryl)–N bond by chromium(0) can take place in a high-spin quintet (S = 2) ground state, whereas the lower-spin singlet (S = 0) and triplet (S = 1) st...

Security and privacy protection is an important research topic in the context of Mobile Crowd Sensing (MCS). The identity authentication involves confirming the identity of a person. In this paper, we propose a pseudonym based anonymous identity authentication mechanism for MCS. We firstly define an attack model for MCS network. Particularly, we combine Public Key Infrastructure (PKI) and Combined Public Key (CPK) technology for key and certificate management to solve the problem of large-scale key management. Finally, We evaluate the proposed anonymous identity authentication mechanism by function testing and performance testing. Substantial experimental results demonstrate the effectiveness of our solutions that contribute to privacy protection for the process of authentication by the means of pseudonym.

Since 1987, the stoichiometric two-step C-H conjugate addition reactions have been developed. Herein we describe the first manganese-catalyzed one-step direct aromatic C-H conjugate addition to α,β-unsaturated carbonyls, which is accelerated by a catalytic amount of dicyclohexylamine. Experimental and computational studies substantiated the validity of the proposed catalytic cycle.

Incentive mechanism is one of the most critical issues in the field of mobile crowd sensing, and plays an important role on ensuring the quantity of participants and the coverage rate of perceived data. In this paper, we review the existing research, and propose a "5W1H" model to serve the study on incentive mechanism. Moreover, we conduct analysis on how to design incentive mechanism with a case "Noise Map". Finally, we point out some open issues in this research area.

The first manganese-catalyzed one-step direct aromatic C—H conjugate addition to α,β-unsaturated carbonyls is presented, which is accelerated by catalytic amounts of dicyclohexylamine.