Alkaloids and Styryl Lactones from and Their Biological Activities.

Phytochemical investigations of the twig and leaf extracts of resulted in the isolation and identification of two new alkaloids, goniotortiline () and goniotortilactam (), three new styryl lactone derivatives, goniotortilactone () and goniotortilols A () and B (), and 25 known compounds. Their structures were elucidated by spectroscopic methods and HRESITOFMS data. Compounds , , , , , and inhibited nitric oxide (NO) production with IC values ranging from 8.

Alkyl initiated ring opening polymerization of lactide by indium complexes supported by NCN pincer ligands.

Indium-alkyl NCN pincer complexes supported by amine and imine donors are active catalysts for the ring opening polymerization of lactide. The amine indium complexes are significantly more active for polymerization due to the decoordination of the amine donors at higher temperatures. Solid state structures of the imine and amine indium complexes indicate that the imine-indium bonds are stronger than the analogous amine-indium bonds.

A Redox-active Cyclometalated Platinum Ring Enables Synthetic Post-processing of a [2]Rotaxane.

Post-synthetic modification of mechanically interlocked molecules (MIMs) is an attractive avenue to add complexity to already intricate systems. This remains an important, challenging topic that is under-developed. In this paper, we report the synthesis and characterization of a [2]rotaxane molecule featuring a ring appended to an emissive cyclometalated Pt unit.

π-Extended ligands with dual-binding behavior: hindered rotation unlocks unexpected reactivity in cyclometalated Pt complexes.

Cyclometalated platinum complexes play a crucial role in catalysis, bioimaging, and optoelectronics. Phenylpyridines are widespread cyclometalating ligands that generate stable and highly emissive Pt complexes. While it is common practice to modify these ligands to fine-tune their photophysical properties, the incorporation of polycyclic aromatic hydrocarbons into the ligand's structure has been largely overlooked.

Enantiopure -Chiral Secondary Phosphines (P*HRR') from the Catalytic Asymmetric Hydrogenation of P═C Bonds.

We report the first bottleable enantiopure -chiral secondary phosphines from the rhodium-catalyzed asymmetric hydrogenation of phosphaalkenes. Catalytic asymmetric hydrogenation, a reaction of broad academic and industrial importance for C═C, N═C, and O═C bonds, has not previously been reported for the P═C bond. The hydrogenation of ArP═CR (Ar = Mes, -Xyl and TMOP; R = Ph, 4-CHF) affords four unprecedented -stereogenic secondary phosphines in 76%-90% isolated yields with 91%-97% enantiomeric excess (ee).

Halide Salts Alleviate TMSOK Inhibition in Suzuki-Miyaura Cross-Couplings.

The Suzuki-Miyaura cross-coupling (SMC) remains one of the most widely used transformations available to chemists. Recently, robust new conditions achieving rapid reactivity under homogeneous aprotic conditions enabled by the use of potassium trimethylsilanolate (TMSOK) as a base were reported. However, the strong inhibitory effect of TMSOK restricts the generality of such conditions.

Synthesis of (2,3,4)-Dihydroxyisoleucine for Use in Amatoxin Synthesis.

We report a streamlined synthesis of (2,3,4)-4,5-dihydroxy isoleucine (DHIle), an amino acid found in α-amanitin, which appears to be critical for toxicity. This synthetic route is transition metal-free and enables the production of significant quantities of DHIle with suitable protection for use in peptide synthesis. Its incorporation into a cytotoxic amatoxin analog is reported.

1,3-Dipolar cyclisation reactions of nitriles with sterically encumbered cyclic triphosphanes: synthesis and electronic structure of phosphorus-rich heterocycles with tunable colour.

We describe the synthesis, solid state and electronic structures of a series of tunable five-membered cationic and charge-neutral inorganic heterocycles featuring a PCN core. 1-Aza-2,3,4-triphospholenium cations [(PR)N(H)CR'], [1] (R' = Me, Ph, 4-MeOCH, 4-CFCH) were formed as triflate salts by the formal [3 + 2]-cyclisation reactions of strained cyclic triphosphanes (PR) (R = Bu, 2,4,6-MeCH (Mes), 2,6- PrCH (Dipp), 2,4,6- PrCH (Tipp)) with nitriles R'CN in the presence of triflic acid. The corresponding neutral free bases (PR)NCR' (2) were readily obtained by subsequent deprotonation with NEt.

Luminescent Platinum(II) Complexes with Stimuli-Responsive Flexible Lewis Pair Ligands: Spectroscopic and Computational Studies.

A series of new luminescent bimetallic platinum(II) complexes with stimuli-responsive flexible Lewis pair (FlexLP) ligands are described. The FlexLP ligands consist of a dimesitylboron Lewis acid and diphenylphosphine oxide Lewis base which are in equilibrium between the unbound open form and the Lewis adduct, controlled by the hydrogen bond donating strength of the solvent. Spectroscopic techniques and density functional theory (DFT) calculations were used to interpret the photophysics of the platinum(II) complexes.

Highly oxygenated cyclohexenes from Uvaria dac Pierre ex Finet & Gagnep. and their α-glucosidase inhibitory activity.

Phytochemical investigations of the twig and leaf extracts of Uvaria dac Pierre ex Finet & Gagnep. resulted in the isolation and identification of five new highly oxygenated cyclohexenes, uvaridacols M - Q (1-3, 5, and 6), and six known compounds (4 and 7-11). All new structures were elucidated by spectroscopic methods and HRESITOFMS data.

Synthesis of Carbene-Stabilized PNPN Fragments and Their Carbene-Dependent Redox Properties.

Herein, we report the synthesis of carbene-stabilized 1,3-diaza-2,4-diphosphabutenes CAACPNPNCAAC (CAAC = 1-[2,6-bis(isopropyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene) and IPrPNPNIPr (IPr = 1,3-Bis(2,6-diisopropylphenyl)-imidazol-2-ylidene). The bonding in both systems is defined by a delocalized polar covalent π-system, with exhibiting increased conjugation relative to . The nature of the stabilizing carbene also influences the redox properties of the compound, with undergoing potassium-mediated reduction to the closed-shell P-P bonded dimer , which upon treatment with Kryptofix-2,2,2 converts to the transient radical anion [K][], the formal one-electron reduction product of .

Diphenylphosphinylhydroxylamine (DPPH) Affords Late-Stage S-imination to access free-NH Sulfilimines and Sulfoximines.

Sulfilimines, as potential aza-isosteres of sulfoxides, are valued as building blocks, auxiliaries, ligands, bioconjugation handles, and as precursors to versatile S(VI) scaffolds including sulfoximines and sulfondiimines. Here, we report a thioether imination methodology that exploits O-(diphenylphosphinyl)hydroxyl amine (DPPH). Under mild, metal-free, and biomolecule-compatible conditions, DPPH enables late-stage S-imination on peptides, natural products, and a clinically trialled drug, and shows both excellent chemoselectivity and broad functional group tolerance.

Wing pattern variation and DNA barcodes defy taxonomic splitting in the New Zealand Pimelea Looper Notoreas perornata (Walker) (Lepidoptera: Geometridae: Larentiinae): the importance of populations as conservation units.

The endemic Notoreas perornata (Walker, 1863) complex (Lepidoptera: Geometridae: Larentiinae) from the North Island and northern South Island of New Zealand is reviewed. Larvae feed on Pimelea spp. (Thymelaeaceae), frequently in highly fragmented and threatened shrubland habitats.

Rhenium(I) Complexes with Sulfur-Bridged Dipyridyl Ligands: Structural, Photophysical, and Computational Studies.

A series of six new rhenium(I) tricarbonyl complexes [Re(CO)(N-N)Br] bearing sulfur-bridged dipyridyl (N-N) ligands with three different oxidation states (sulfide (S), sulfoxide (SO), and sulfone (SO)) are described. Spectroscopic studies show that changing the oxidation state of the ligands influences the photophysical properties of the complexes, with complexes and containing the sulfone ligand exhibiting a lower energy MLCT absorption band tailing into the visible region. Solution-state emission measurements show that these complexes exhibit readily tunable emission energies from 480 to 610 nm, depending on the oxidation state of the sulfur bridge and the presence of substituents on the pyridyl rings.

Linear Free Energy Relationships and Transition State Analysis of CO Reduction Catalysts Bearing Second Coordination Spheres with Tunable Acidity.

In molecular catalysts, protic functional groups in the secondary coordination sphere (SCS) work in conjunction with an exogenous acid to relay protons to the active site of electrochemical CO reduction; however, it is not well understood how the acidity of the SCS and exogenous acid together determine the kinetics of catalytic turnover. To evaluate the relative contributions of proton transfer driving forces, we synthesized a series of modular iron tetraphenylporphyrin electrocatalysts bearing SCS amides of tunable p (17.6 to 20.

New norclerodane diterpenoids from bulbils of L.

Investigation of extracts from bulbils of L. yielded two new norclerodane diterpenoids, diosbulbin N acetate () and -diosbulbin B (), together with eleven known compounds. Their structures were established based on spectroscopy.

Biogeographic-tectonic calibration of 14 nodes in a butterfly timetree.

The butterfly subtribe Coenonymphina (Nymphalidae: Satyrinae) comprises four main clades found, respectively, in (1) the Solomon Islands, (2) Australasia, (3) NW South America and (4) Laurasia, with a phylogeny: 1 (2 (3 + 4)). In assessing biogeographic evolution in the group we rejected the conversion of fossil-calibrated clade ages to likely maximum clade ages by the imposition of arbitrary priors. Instead, we used biogeographic-tectonic calibration, with fossil-calibrated ages accepted as minima.

A specific dispiropiperazine derivative that arrests cell cycle, induces apoptosis, necrosis and DNA damage.

Dispiropiperazine compounds are a class of molecules known to confer biological activity, but those that have been studied as cell cycle regulators are few in number. Here, we report the characterization and synthesis of two dispiropiperazine derivatives: the previously synthesized spiro[2',3]-bis(acenaphthene-1'-one)perhydrodipyrrolo-[1,2-a:1,2-d]-pyrazine (SPOPP-3, 1), and its previously undescribed isomer, spiro[2',5']-bis(acenaphthene-1'-one)perhydrodipyrrolo-[1,2-a:1,2-d]-pyrazine (SPOPP-5, 2). SPOPP-3 (1), but not SPOPP-5 (2), was shown to have anti-proliferative activity against a panel of 18 human cancer cell lines with IC values ranging from 0.

Synthesis of a Carbene-Stabilized (Diphospha)aminyl Radical and Its One Electron Oxidation and Reduction to Nonclassical Nitrenium and Amide Species.

Herein, we report the synthesis of an acyclic carbene-stabilized diphospha(aminyl) PNP radical CAACPNPCAAC (CAAC = 1-[2,6-bis(isopropyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene) by a facile one-pot, seven-electron reduction of hexachlorophosphazene chloride [ClPNPCl][Cl]. The PNP radical features a conjugated framework with spin density primarily localized on the central nitrogen atom as well as the flanking carbenes. Unlike other tripnictogen radicals, undergoes facile one-electron oxidation and reduction to yield nonclassical nitrenium and amide species [] and [], respectively.

A Crystalline Monomeric Phosphaborene.

We report the synthesis of the monomeric phosphaborene Ar*P═B(TMP) () (Ar* = 2,6-bis(triisopropylphenyl)-3,5-diisopropylphenyl) containing 2-coordinate phosphorus and boron centers. Compound has a PB bond length of 1.741(3) Å, the shortest reported to date.

Investigating the mechanism of Ni-mediated trifluoromethylthiolation of aryl halides using AgSCF.

The mechanism of the Ni-catalysed trifluoromethylthiolation of aryl chlorides using AgSCF is studied herein. A variety of IPr Ni complexes were synthesized oxidative addition of Ni to 2-(2-chloro)phenylpyridines. Their reactivity with AgSCF was tested by performing stoichiometric experiments, cyclic voltammetry, and NMR spectroscopic studies.

Toward Ga and Cu Positron Emission Tomography Probes: Is Hdedpa-,'-pram the Missing Link for dedpa Conjugation?

Hdedpa-,'-pram (HL), a new chelator derived from the hexadentate ligand 1,2-bis[[(6-carboxypyridin-2-yl)methyl]amino]ethane (Hdedpa), which incorporates 3-propylamine chains anchored to the secondary amines of the ethylenediamine core of the latter, has emerged as a very promising scaffold for preparing Ga- and Cu-based positron emission tomography probes. This new platform is cost-effective and easy to prepare, and the two pendant primary amines make it versatile for the preparation of bifunctional chelators by conjugation and/or click chemistry. Reported herein, we have also included the related Hdedpa-,'-prpta (HL) platform as a simple structural model for its conjugated systems.

Dimeric aporphine alkaloids from the twigs of Trivalvaria costata (Hook.f. & Thomson) I.M.Turner.

A phytochemical investigation of the twig extract of Trivalvaria costata (Hook.f. & Thomson) I.

Cycling a Tether into Multiple Rings: Pt-Bridged Macrocycles for Differentiated Guest Recognition, Pseudorotaxane Transformations, and Guest Capture and Release.

Macrocycle engineering is a key topic in supramolecular chemistry. When synthesizing a ring, one can obtain either complex mixtures of macrocycles of different sizes or a single ring if a template is utilized. Here, we unite these approaches along with post-synthetic modifications to transform a single tether into multiple rings-up to five per tether.

Noncooperative guest binding by metal-free [2 + 2] Schiff-base macrocycles.

Salphen-based [ + ] macrocycles have been widely explored for their unique chemical and topological properties following metal ion coordination. Despite having vastly different reactivity than their coordinated counterparts, fewer studies have focused on metal-free salphen macrocycles. We investigated the binding of [2 + 2] Schiff-base macrocycle host 3, which contains a central 18-crown-6-like cavity and two NO moieties.