Rhodium(I)/Chiral Diene Complexes Catalyzed Asymmetric Desymmetrization of Alkynyl-Tethered 2,5-Cyclohexadienones Through an Arylative Cyclization Cascade.

Cis-hydrobenzofurans, cis-hydroindoles, and cis-hydrindanes, privileged structural motifs found in numerous biologically active natural and synthetic compounds, are efficiently prepared by a Rh(I)-catalyzed cascade syn-arylation/1,4-addition protocol. This approach starts with the regioselective syn-arylation of the alkyne tethered to 2,5-hexadienone moieties, using a chiral Rh(I) catalyst generated in situ from a chiral bicyclo[2.2.1]hepatadiene ligand L4f. By forging two new carbon-carbon bonds and introducing two chiral centers, the resulting alkenylrhodium species undergoes desymmetrization via an intramolecular 1,4-addition reaction, delivering annulated products with high yields and enantioselectivities.

A Bis-Cyclopentadienyl Ligand-Supported Di-Iron Trihydride Motif as a Synthon for Access to Heterobimetallic Trinuclear Complexes.

Herein, we report the synthesis of a flexible bis-cyclopentadienyl ligand L (the doubly deprotonated form of H2L (1,3-bis(2,4-di-tert-butylcyclopentadienyldimethylsilyl)benzene)), demonstrating its ability to stabilize a series of di-iron hydrido complexes. Notably, this ligand facilitates the isolation of an unprecedented anionic cyclopentadienyl ligand-supported di-iron trihydride complex, LFe2(µ-H)3Li(THF) (2), functioning as a synthon for the [Fe2(µ-H)3]- core and providing access to heterobimetallic complexes 4-6 with coinage metals.

Complications and psychological impact of pressure ulcers on patients and caregivers.

Pressure ulcers are persistent skin lesions that have substantial detrimental effects on the physical well-being of patients. Moreover, their psychological ramifications for both patients and their caregivers are becoming more widely acknowledged. This research was conducted to examine the psychological ramifications of pressure ulcers and ascertain efficacious approaches to mitigate these effects and improve overall well-being. A cross-sectional study was conducted from March 2022 to December 2023 across tertiary care centres located in Beijing. The cohort consisted of 431 participants, which included primary caregivers and patients who were diagnosed with pressure ulcers. The data were gathered through the utilization of structured questionnaires and semi-structured interviews. These methods encompassed demographic details, clinical characteristics and validated scales that assessed psychological parameters, including quality of life, anxiety, stress and depression. The research exposed substantial psychological toll on both individuals receiving care and those providing care, with caregivers enduring diminished quality of life and elevated levels of anxiety, depression and stress (p < 0.05). A significant positive correlation was identified between the degree of psychological distress and severity of pressure ulcers (p < 0.05). Both location of the ulcer and duration of care were substantial contributors to the psychological burden (p < 0.05). In spite of the apparent necessity, a significant proportion of the participants refrained from obtaining psychological counselling. The results underscored the significant psychological ramifications of pressure ulcers for both individuals receiving care and the caregivers. As a result, comprehensive care strategies that incorporate psychological assistance into the prescribed treatment plan are imperative. This research highlighted the criticality of implementing all-encompassing, interdisciplinary approaches to tackle the complex issues presented by pressure ulcers in an effort to enhance the general welfare of those influences.

Isolable Tin(II) Hydrides Featuring Sterically Undemanding Pincer-Type Ligands and Their Dehydrogenative Sn-Sn Bond Forming Reactions to Distannynes Promoted by Lewis Acidic Tri-sec-butylborane.

Unlike isolable tin(II) hydrides supported by bulky ligands reported in the literature, this research describes the synthesis and characterization of thermally stable tin(II) hydrides LPhSnH (1-H) and MeLSnH (2-H) stabilized by sterically undemanding N,N,N-coordinating pincer-type ligands (LPh = 2,5-dipyridyl-3,4-diphenylpyrrolato; MeL = 2,5-bis(6-methylpyridyl)pyrrolato). The results from previous reports reveal that attempts to access tin(II) hydrides containing less-bulky ligands have had limited success, and decomposition to tin(I) distannynes often occurs. The key to the successful isolation of 1-H and 2-H is the identification of the role of Lewis acidic BsBu3, generated upon delivering hydride from commonly used hydride reagents M[BsBu3H] ("selectrides", M = Li or K). This study details compelling experimental evidence and theoretical results of the role played by BsBu3, which catalyzes the dehydrocoupling reactions of 1-H and 2-H to yield tin(I) distannynes LPhSn-SnLPh (12) and MeLSn-SnMeL (22) with the liberation of H2. To avoid the interference of BsBu3, 1-H and 2-H can be isolated in pure forms using pinacolborane as the hydride donor with LPhSnOMe (1-OMe) and MeLSnOMe (2-OMe) as reactants, respectively. DFT calculations and experimental observations indicate that the coordination of the Sn-H bond of 1-H to BsBu3 leaves an electrophilic tin center, rendering the nucleophilic attack by the second equivalent of 1-H forming a Sn-Sn bond.

Parallel Evolution of Common Allelic Variants Confers Flowering Diversity in Capsella rubella.

Flowering time is an adaptive life history trait. Capsella rubella, a close relative of Arabidopsis thaliana and a young species, displays extensive variation for flowering time but low standing genetic variation due to an extreme bottleneck event, providing an excellent opportunity to understand how phenotypic diversity can occur with a limited initial gene pool. Here, we demonstrate that common allelic variation and parallel evolution at the FLC locus confer variation in flowering time in C. rubella. We show that two overlapping deletions in the 5' untranslated region (UTR) of C. rubella FLC, which are associated with local changes in chromatin conformation and histone modifications, reduce its expression levels and promote flowering. We further show that these two pervasive variants originated independently in natural C. rubella populations after speciation and spread to an intermediate frequency, suggesting a role of this parallel cis-regulatory change in adaptive evolution. Our results provide an example of how parallel mutations in the same 5' UTR region can shape phenotypic evolution in plants.

Polyploidy promotes species diversification of Allium through ecological shifts.

Despite the role of polyploidy in multiple evolutionary processes, its impact on plant diversification remains controversial. An increased polyploid frequency may facilitate speciation through shifts in ecology, morphology or both. Here we used Allium to evaluate: (1) the relationship between intraspecific polyploid frequency and species diversification rate; and (2) whether this process is associated with habitat and/or trait shifts. Using eight plastid and nuclear ribosomal markers, we built a phylogeny of 448 Allium species, representing 46% of the total. We quantified intraspecific ploidy diversity, heterogeneity in diversification rates and their relationship along the phylogeny using trait-dependent diversification models. Finally, we evaluated the association between polyploidisation and habitat or trait shifts. We detected high ploidy diversity in Allium and a polyploidy-related diversification rate shift with a probability of 95% in East Asia. Allium lineages with high polyploid frequencies had higher species diversification rates than those of diploids or lineages with lower polyploid frequencies. Shifts in speciation rates were strongly correlated with habitat shifts linked to particular soil conditions; 81.7% of edaphic variation could be explained by polyploidisation. Our study emphasises the role of intraspecific polyploid frequency combined with ecological drivers on Allium diversification, which may explain plant radiations more generally.

Mononuclear Manganese(III) Superoxo Complexes: Synthesis, Characterization, and Reactivity.

Metal-superoxo species are typically proposed as key intermediates in the catalytic cycle of dioxygen activation by metalloenzymes involving different transition metal cofactors. In this regard, while a series of Fe-, Co-, and Ni-superoxo complexes have been reported to date, well-defined Mn-superoxo complexes remain rather rare. Herein, we report two mononuclear MnIII-superoxo species, Mn(BDPP)(O2•-) (2, H2BDPP = 2,6-bis((2-(S)-diphenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) and Mn(BDPBrP)(O2•-) (2', H2BDPBrP = 2,6-bis((2-(S)-di(4-bromo)phenylhydroxyl-methyl-1-pyrrolidinyl)methyl)pyridine), synthesized by bubbling O2 into solutions of their MnII precursors, Mn(BDPP) (1) and Mn(BDPBrP) (1'), at -80 °C. A combined spectroscopic (resonance Raman and electron paramagnetic resonance (EPR) spectroscopy) and computational study evidence that both complexes contain a high-spin MnIII center (SMn = 2) antiferromagnetically coupled to a superoxo radical ligand (SOO• = 1/2), yielding an overall S = 3/2 ground state. Complexes 2 and 2' were shown to be capable of abstracting a H atom from 2,2,6,6-tetramethyl-1-hydroxypiperidine (TEMPO-H) to form MnIII-hydroperoxo species, Mn(BDPP)(OOH) (5) and Mn(BDPBrP)(OOH) (5'). Complexes 5 and 5' can be independently prepared by the reactions of the isolated MnIII-aqua complexes, [Mn(BDPP)(H2O)]OTf (6) and [Mn(BDPBrP)(H2O)]OTf (6'), with H2O2 in the presence of NEt3. The parallel-mode EPR measurements established a high-spin S = 2 ground state for 5 and 5'.

Reversible Laser-Induced Bending of Pseudorotaxane Crystals.

This study investigated the dynamic photoresponse of pseudorotaxane crystals with azobenzene and ferrocenyl groups in the axle component. X-ray crystallography showed pseudorotaxanes with a methylazobenzene group and a dibromophenylene ring in the cyclic component to exhibit twisting of the trans-azobenzene groups at torsion angles of 17° and 38°, respectively. Repeated alternating laser irradiation of the crystals at 360 and 445 nm produced bending of 20-30° in opposite directions, with no evidence of decay. Under 445 nm irradiation, bending took place within 0.3 s. A crystal of nonsubstituted pseudorotaxane showed bending of only 2° under 360 nm irradiation due to multiple π-π interactions between the planar trans-azobenzene groups. The pseudorotaxane crystals have two chromophores, bent rapidly and reversibly on irradiation at rates depending on the molecular structure.

Access to ß2-Amino Acids via Enantioselective 1,4-Arylation of ß-Nitroacrylates Catalyzed by Chiral Rhodium Catalysts.

The highly enantioselective conjugate addition of a variety of arylboronic acids to ß-nitroacrylates is reported to provide optically active α-aryl ß-nitropropionates in up to 70% yields and >99.5% ee's, which are useful building blocks for preparing chiral ß2-amino acids. The applicability of this transformation is demonstrated by converting 3aa into the ß2-amino acid 5 and transforming 3ap to ß-amino ester 7 via reduction and reductive N-alkylation. The latter compound is a precursor for preparing ent-ipatasertib.

Directed Self-Assembly of C4-Symmetric, Oxidovanadate-Centered, Vanadyl(V) Quadruplexes for Ba2+- and Hg2+-Specific Recognition, Transport, and Recovery.

Directed assembly of loosely, Na+-bound, oxidovanadate-centered quartets of C4-symmetry from tailor-made chiral N-salicylidene-vanadyl(V) complexes, for the first time, allows for highly efficient Ba2+- or Hg2+-specific detection (by 51V NMR and VCD), transport (forming a unique helical capsule or a capped square planar complex, respectively), and green recovery from an aqueous phase containing 4 different alkaline earth ions or from at least 10 different metal ions of similar size and charge capacity into the CHCl3 layer without interference from oxa- or oxophilic ions like Mg2+, Ca2+, Cu2+, Cd2+, and Pb2+.

Ligand-Unsupported Cuprophilicity in the Preparation of Dodecacopper(I) Complexes and Raman Studies.

Synthesis and characterization of two dodecacopper(I) extended metal atom chains (EMAC) assembled by two hexadentate bis(pyridylamido)amidinate-supported hexacopper(I) string complexes (monomers) via the ligand-unsupported cuprophilicity are described. In addition to short unsupported Cu-Cu contacts, two hexacopper fragments in these two dodecacopper EMACs show a bent conformation based on X-ray crystallography. Compared with their THF-bound hexacopper(I) monomers and protonated ligands, these ligand-unsupported cuprophilic interactions are shown to be weak by Raman spectroscopy. DFT calculations suggest the ligand-unsupported cuprophilicity originate from weak attractive orbital interactions, and the strength is estimated to be 2.4 kcal mol-1 .

Molecular ReI Cages: Structural and Luminescent Properties.

Versatile building block [{Re(CO)4 }3 (C3 N3 S3 )] (1 a; C3 N3 S3 =cyanurate trianion) reacts with linear dipyridyl ligands [i.e., pyrazine (pz), 4,4'-bipyridine (bpy), 1,2-bis(4-pyridyl)ethylene (bpe), bis(4-pyridyl)acetylene (bpa), and 1,4-bis(pyridyl-4-ylethynyl)benzene (bpb)] and a tripyridyl ligand [1,3,5-tris(4-pyridylethynyl)benzene (tpb)] to afford a series of molecular cages [{Re(CO)3 }6 (L)3 (C3 N3 S3 )2 ] [L=pz (2), bpy (3), bpe (4), bpa (5), bpb (6)] and [{Re(CO)3 }9 (tpb)3 (C3 N3 S3 )3 ] (7) under solvothermal conditions. Various structural dimensions and motifs can be systematically tuned and obtained by using different dipyridyl and tripyridyl ligands in the reactions. The molecular cages of hexanuclear complexes 2-6 containing dipyridyl ligands feature interesting trigonal-prismatic structures with different dimensions. Furthermore, nonanuclear complex 7 has a novel triangular-star structure, and three benzene rings of tpb ligands form a triple-decker arrangement with significant π⋅⋅⋅π interactions having distances of 3.490(1) and 3.528(1) Å. In addition, molecular cages 1-3 and 5-7 exhibit luminescence in the solid state, and their luminescent properties were also studied.

Synthesis of Quaternary-Carbon-Containing ß2,2 -Amino Acids by the RhI -Catalyzed Enantioselective Arylation of α-Substituted ß-Nitroacrylates.

An enantioselective RhI -catalyzed conjugate addition reaction of α-substituted ß-nitroacrylates with various arylboronic acids by using chiral RhI diene catalysts is described for the first time. The addition reaction proceeds under mild conditions in a range of common organic solvents and additives, and it affords the corresponding quaternary-carbon-containing α,α-disubstituted ß-nitropropionate products in up to 63 % yield and 99 % ee. Reaction of either (E)- or (Z)-ß-nitroacrylates provided the same enantiomer of the product, and a range of esters and aryl groups were tolerated. To demonstrate the utility of the method, ethyl (R)-1,1-methyl-1-phenyl-3-nitropropionate, prepared herein, was converted to the non-proteinogenic ß2,2 -amino acid, (R)-2-(aminomethyl)-2-phenylpropanoic acid, and to the ß2,2 -lactam, (R)-3-methyl-3-phenylazetidin-2-one. In addition, a tripeptide, which comprised l-phenylalanine, l-alanine, and ß2,2 -amino acid 7, was also synthesized.

Design and Synthesis of Chiral Diene Ligands for RhI -Catalyzed Enantioselective Arylation of N-DPP-protected Aldimines: Synthesis of the Antifungal Agent Bifonazole.

Herein we describe the design and synthesis of a novel family of bifunctional, chiral bicyclo[2.2.1]heptadiene ligands bearing aryl and secondary amido groups, and demonstrate their usefulness in the RhI -catalyzed enantioselective addition reaction of arylboronic acids to N-diphenylphosphinyl (N-DPP)-protected aldimines. Unlike the analogous RhI -catalysts comprising diene ligands substituted with aryl and carboxylic ester groups, or only with aryl groups, the addition reaction proceeded with high stereoselectivity. The protocol tolerated a range of N-DPP-aldimines and arylboronic acids, producing the desired optically active N-DPP-protected amines with yields between 31-99 % and with ee values up to 91-99 %. The synthetic utility of the method was demonstrated by the conversion of N-DPP-protected amine 3 ae into the antifungal agent, bifonazole (13).

Synthesis and Characterization of an Eclipsed Digermylene as a Building Block to Construct a Cyclic Octagermylene.

The preparation of an unprecedented GeI -GeI bonded digermylene [K2 {Ge2 (µ-κ2 :η2 :η4 -2,6-(2,6-i Pr2 C6 H3 -N)2 -4-CH3 C5 H2 N)2 }] in an eclipsed conformation stabilized by two bridging diamidopyridyl ligands is presented. Although it exhibits an eclipsed conformation, the Ge-Ge bond length is 2.5168(6) Å, which is shorter than those in the trans-bent and gauche digermylenes. In combination with two pendant amido groups, the GeI2 motif is employed as a building block to assemble the first example of octagermylene [Ge4 (µ-κ2 :κ1 -2,6-(2,6-i Pr2 C6 H3 -N)2 -4-CH3 C5 H2 N)2 ]2 showing a cyclic configuration and containing three distinct types of GeI -GeI bonds.

A Structurally Characterized Nonheme Cobalt-Hydroperoxo Complex Derived from Its Superoxo Intermediate via Hydrogen Atom Abstraction.

Bubbling O2 into a THF solution of CoII(BDPP) (1) at -90 °C generates an O2 adduct, Co(BDPP)(O2) (3). The resonance Raman and EPR investigations reveal that 3 contains a low spin cobalt(III) ion bound to a superoxo ligand. Significantly, at -90 °C, 3 can react with 2,2,6,6-tetramethyl-1-hydroxypiperidine (TEMPOH) to form a structurally characterized cobalt(III)-hydroperoxo complex, CoIII(BDPP)(OOH) (4) and TEMPO•. Our findings show that cobalt(III)-superoxo species are capable of performing hydrogen atom abstraction processes. Such a stepwise O2-activating process helps to rationalize cobalt-catalyzed aerobic oxidations and sheds light on the possible mechanism of action for Co-bleomycin.

Encapsulation of Formaldehyde and Hydrogen Cyanide in an Open-Cage Fullerene.

Reaction of C63 NO2 (Ph)2 (Py) (1) with o-phenylenediamine and pyridine produces a mixture of C63 H4 NO2 (Ph)2 (Py)(N2 C6 H4 ) (2) and H2 O@2. Compound 2 is a new open-cage fullerene containing a 20-membered heterocyclic orifice, which has been fully characterized by NMR spectroscopy, high-resolution mass spectrometry, and X-ray crystallography. The elliptical orifice of 2 spans 7.45 Šalong the major axis and 5.62 Šalong the minor axis, which is large enough to trap water and small organic molecules. Thus, heating a mixture of 2 and H2 O@2 with hydrogen cyanide and formaldehyde in chlorobenzene affords HCN@2 and H2 CO@2, respectively. The (1) H NMR spectroscopy reveals substantial upfield shifts for the endohedral species (δ=-1.30 to -11.30 ppm), owing to the strong shielding effect of the fullerene cage.

Reactivity of a Fe(III)-Bound Methoxide Supported with a Tris(thiolato)phosphine Ligand: Activation of C-Cl Bond in CH2Cl2 by Nucleophilic Attack of a Fe(III)-OCH3 Moiety.

Two mononuclear nonheme Fe(III) complexes, [PPh4][Fe(III)(PS3″)(OCH3)] (1) and [PPh4][Fe(III)(PS3″)(Cl)] (2), supported by a tris(benzenethiolato)phosphine derivative PS3″ (PS3″ = P(C6H3-3-Me3Si-2-S)3(3-)) have been synthesized and characterized. The structures resolved from X-ray crystallography show that Fe(III) centers in both complexes adopt distorted trigonal-bipyramidal geometry with a methoxide or a chloride binding in the axial position. The magnetic data for both are consistent with intermediate-spin Fe(III) centers with a C3 symmetry (S = 3/2 ground state). The bound methoxide in 1 is labile and can be replaced by a CH3CN molecule. The forming Fe(III)-CH3CN species can be further reduced by cobaltcene quantitatively to a stable Fe(II)-CH3CN complex, [Fe(PS3″)(CH3CN)](-). One-electron oxidation of 2 by ferrocenium gave a Fe(IV) analogue, [Fe(IV)(PS3″)(Cl)]. Importantly, the Fe(III)-OCH3 moiety in complex 1 acts as a strong nucleophile that activates the C-Cl bond in CH2Cl2, leading to the formation of complex 2 quantitatively. Complex 1 also reacts with other electrophiles, benzyl chloride and benzyl bromide, to generate Fe(III)-X species (X = Cl or Br). The reactions were investigated and monitored by UV-vis-NIR, NMR, and ESI-MS spectroscopies.

A Family of Multiply Bonded Dimolybdenum Boraamidinates with the Formal Mo-Mo Bond Orders of 3, 4, 4.5, and 5.

A boraamidinato ligand [PhB(N-2,6-(i) Pr2 C6 H3 )2 ](2-) was employed to stabilize a new family of multiply bonded dimolybdenum complexes [MoCl(µ-κ(2) -PhB(N-2,6-(i) Pr2 C6 H3 )2 )]2 (4) and [Mo(µ-κ(2) -PhB(N-2,6-(i) Pr2 C6 H3 )2 )]2 (n-) (n=0 (5), 1 (6), 2 (7)), with the respective formal Mo-Mo bond orders of 3, 4, 4.5, and 5. Each metal center in 5-7 is two-coordinate with respect to the ligands. Of particular interest is the quadruply bonded dimolybdenum complex 5, featuring an unprecedented angular conformation. The bent Mo2 N4 core of 5 distorts toward planarity upon reduction. As a result, compound 7 features a planar Mo2 N4 core, while that of 6 is still bent but less significantly than that of 5. Additionally, the Mo-Mo bond lengths of 4-7 systematically decrease as the valency of the central Mo2 units decreases. Complex 7 features the shortest Mo-Mo bond length (2.0106(5) Å) yet reported.

Direct synthesis of chiral 3-arylsuccinimides by rhodium-catalyzed enantioselective conjugate addition of arylboronic acids to maleimides.

Chiral rhodium catalysts comprising 2,5-diaryl- substituted bicyclo[2.2.1]diene ligands L1-L10 were utilized in the enantioselective 1,4-addition reaction of arylboronic acids to N-substituted maleimides. In the presence of 2.5 mol % of Rh(I) /L2, enantioenriched conjugate addition adducts were isolated in 72-99 % yields with 86-98 % ee. This protocol offers a convenient method to access a variety of 3-arylsuccinimides in a highly enantioselective manner. Maleimides with readily cleavable N-protecting groups were tolerated enabling the synthesis of useful synthetic intermediates. Pyrrolidine 4, a biologically active compound, and pyrrolidine 5, an ent-precursor to an HSD-1 inhibitor, were synthesized to demonstrate the utility of this method.