A lasso peptide biosynthetic gene cluster (BGC) was identified through genome mining in the species Streptacidiphilus jiangxiensis CGMCC 4.1857, which was isolated from acidic rhizosphere soil. The BGC was reconstructed in Escherichia coli, leading to the heterologous production of a lasso peptide named streptacidin. The solution structure of streptacidin was determined based on the distance constraints derived from the NOESY spectrum, establishing the first lasso peptide utilizing methionine as a steric lock for the unique spatial configuration and the remarkable stability against heat (up to 95 degrees C) and proteolytic degradation by carboxypeptidase Y and chymotrypsin. Under experimental conditions, streptacidin showed weak effectiveness against vancomycin sensitive Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 902. These findings further the understanding of this distinctive class of compounds.

The asymmetric Tsuji-Trost reaction has been extensively studied due to its importance in establishing stereogenic centers, often adjacent to an E-olefin moiety in organic molecules. The generally preferential formation of chiral E-olefin products is believed to result from the thermodynamically more stable syn-pi-allylpalladium intermediate. The rapid associative pi-sigma-pi isomerization makes it challenging to synthesize chiral Z-olefin products via the transient anti-pi-allylpalladium intermediate. Herein, we report a strategy for regulating associative pi-sigma-pi isomerization by tuning the steric bulkiness of the ligands, allylic leaving groups, and counteranions. The utilization of a Pd catalyst derived from chiral phosphoramidite ligands interrupts the associative pi-sigma-pi isomerization, enabling a highly efficient Z-retentive asymmetric Tsuji-Trost reaction toward an array of alpha-amino acid derivatives bearing a Z-olefin motif in high yields (up to 95%) and excellent stereoselectivity (up to 99% ee and >19:1 Z/E) with low catalyst loading (0.1 mol %). The mechanistic insights and the design strategy reported in this work pave the way for rational developments of Z-retentive asymmetric Tsuji-Trost-type reactions.

Zwitterionic pi-allenyl palladium species are newly developed intermediates. A substrate-controlled step existed in the cycloaddition of zwitterionic pi-allenyl palladium species with tropsulfimides or tropones. With the assistance of previously experimental studies, zwitterionic allenyl/propargyl palladium species was provenly found by HRMS. Further DFT calculation studies show that zwitterionic pi-allenyl palladium species are generated through the oxidative addition of Pd(0), which can be promoted by Lewis acid like Yb(OTf)3, and the cycloaddition more likely undergoes through an outer sphere nucleophilic attack. The isomerization is caused by the difference of dissociation energy between the cycloaddition intermediation of tropsulfimides and tropones, forming the substrate-controlled specificity.

The properties of higher triplet excited states (T-n, n >= 2) are essential for deep understanding of excited state dynamics, but direct observation of T-n phosphorescence remains rare, let alone systematic studies of T-n behaviors based on well-designed luminescence molecules. Recently, a serendipitous finding of T-n (n >= 2) afterglow (phosphorescence lifetime > 0.1 s) in benzophenone-containing difluoroboron beta-diketonate (BPBF2) system is communicated. Here Cl/Br/I atoms are covalently incorporated into BPBF2 molecules and report the first systematic study of heavy atom effect (HAE) on T-n (n >= 2) afterglow. It is known that Cl/Br/I HAE has been widely reported and thoroughly studied in T-1 afterglow systems, which shows that Br atom is usually the optimized selection for balancing T-1 afterglow efficiency and lifetime. In contrast, the covalent linkage of Br atom to BPBF2 has been found to dramatically suppress T-n (n >= 2) afterglow. The experimental emission intensity(T-2)/intensity(T-1) ratios are positively correlated with k(IC)(T-1-T-2)/k(IC)(T-2-T-1) x k(P)(T-2)/k(P)(T-1), where k(IC) and k(P) refer to the rates of calculated internal conversion and phosphorescence emission. These fundamental studies would be helpful for elucidating the panorama of Perrin-Jablonski diagram of organic systems and provide intriguing T-n (n >= 2) afterglow materials for future applications.

Methodological studies on the transformations of vinylidene cyclopropanes (VDCPs) have been substantially developed in the past few decades, and significant progress has been achieved in visible light-mediated, non-metal-related, and transition metal-catalyzed processes. In particular, when reactive functional groups are introduced into the backbone of VDCPs, a variety of cascade or sequential transformations can take place to produce more complex cyclic or polycyclic compounds. This review describes the recent advancements in this field.

Axially chiral phosphines are a class of extremely important ligands in asymmetric catalysis. Herein, an unprecedented copper (I)-catalyzed asymmetric SNAr reaction with HP(S)R-2 is uncovered, which delivers a series of axially chiral phosphine derivatives in high yields with excellent enantioselectivity. Furthermore, the diastereoselective reaction with the kinetic resolution of racemic HP(S)ArR proceeds smoothly, providing the products with moderate diastereoselectivity and excellent enantioselectivity. Control experiments indicate that HP(S)Ph-2 is much more active than HPPh2 and HP(O)Ph-2 as the pronucleophile in the present reaction. It is found that the SNAr reaction (the first SNAr) proceeds in a desymmetric manner, providing the desired chiral products while a continued SNAr reaction (the second SNAr) slightly occurs in a kinetic resolution manner in the present catalytic system, which enhances the ee of the desired chiral products. DFT calculations support a concerted reaction pathway rather than a step-wise mechanism. Finally, axially chiral olefin-phosphines produced by the present method work as suitable ligands in Pd-catalyzed asymmetric allylic substitution with C-, N-, and O-nucleophiles and Rh-catalyzed asymmetric addition of arylboronic acid to benzil.

In this issue of Molecular Cell, Sun et al. reveal that the long non-coding RNA (lncRNA) DNAJC3-AS1 plays a dual role in maintaining the rRNA processing function of fibrillarin (FBL) in cancer cells. It promotes FBL condensation while preventing abnormal aggregation, offering new therapeutic insights for cancer treatment by targeting lncRNAs involved in the regulation of FBL condensation.

This study tackles the challenge of enantiodifferentiation of nitrile compounds, which is typically difficult to resolve using nuclear magnetic resonance (NMR) due to the significant distance between the chiral center and the nitrogen atom involved in molecular interactions. We have developed novel chiral 19F-labeled probes, each featuring two chiral centers, to exploit the match-mismatch effect, thereby enhancing enantiodiscrimination. This strategy effectively differentiates chiral analytes with quaternary chiral carbon centers as well as those with similar substituents at the chiral center. Our approach not only provides a novel method for precise probe performance optimization but also offers a rapid and efficient technique for screening reaction conditions in asymmetric synthesis.

A dual photoredox/cobalt-catalyzed protocol for chemo-, regio-, diastereo- and enantioselective reductive coupling of 1,1-disubstituted allenes and cyclobutenes through chemo-, regio-, diastereo- and enantioselective oxidative cyclization followed by stereoselective protonation promoted by a chiral phosphine-cobalt complex is presented. Such process represents an unprecedented reaction pathway for cobalt catalysis that enables selective transformation of the less sterically congested alkenes of 1,1-disubstituted allenes with cyclobutenes, incorporating a broad scope of tetrasubstituted alkenes into the cyclobutane scaffolds in up to 86 % yield, >98 : 2 chemo- and regioselectivity, >98 : 2 dr and >99.5:0.5 er. Functionalization delivered a variety of enantioenriched cyclobutanes that are otherwise difficult to access. Preliminary mechanistic studies revealed that the reactions proceeded through oxidative cyclization followed by protonation and protonation might be the rate-determining step.

Dirhodium(II) complexes have achieved great success in organic synthesis, and fine-tuning their catalytic properties with various bridging ligands is well-investigated in carbene chemistry. However, combining dirhodium(II) with a sophisticated ligand as a catalyst in other reactions is still extremely challenging, especially for the asymmetric synthesis of valuable chiral molecules. Herein, we report a dirhodium(II)/(S)-MeO-BIPHEP catalytic system for the challenging asymmetric beta-alkenylation of alpha,beta-unsaturated aldehydes, affording the corresponding chiral conjugate addition products in good yields with high enantioselectivities. A couple of drug-derived substrates were also compatible with the protocol, which has been successfully used to prepare biologically relevant pyranochromene compounds. Preliminary mechanistic studies suggested that the dirhodium core might remain intact over the catalytic cycle, and the chiral diphosphine ligand plays a key role in this novel reactivity and determining the high enantioselectivities of the asymmetric conjugate addition.