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The synthesis of tetra 4-(3-tert-butyl-4-methoxyphenoxy) benzene cobalt (II) phthalocyanine (CoTTBMPPc) from cobalt (II) tetracarboxylic acid phthalocyanine (CoTCAPc) via Oxygen Bridge. These macro...

The spectral and luminescent properties of compounds A3–SA, A4–o–SA, and A4–o–K have been studied, whose structures include moieties of triphenylimidazole A3, tetraphenylimidazole A4, and hydroxyazomethines salicylideneaniline SA and coumarin-substituted azomethine K. Due to electronic conjugation of moieties, the compound A3–SA exhibits switchable luminescence only in alcohol solutions, whereas independent behavior of the moieties is observed in the case of linking of these luminophores by an oxygen bridge and luminescence switching by changing the excitation wavelength is possible both in solutions and polymeric media.

This work reports the synthesis, crystal structures, and electronic properties of structurally constrained S,C,C- and O,C,C-bridged triarylamine derivatives and their persistent radical cations. O,C,C-Bridged triphenylamines and a dinaphthylphenylamine were obtained through a straightforward synthetic protocol. Similar to a previously reported S,C,C-bridged triphenylamine, the O,C,C-bridged triarylamines were easily oxidized to afford the corresponding radical cations, which were obtained as hexachloroantimonate salts. X-ray crystallographic analyses showed almost planar structures for these O,C,C-bridged triarylamine radical cations, which represent new members of the family of planar triarylamine radical cations without substituents on the aryl rings. Detailed investigations of the electronic properties of the S,C,C- and O,C,C-bridged triarylamine radical cations demonstrated that the spin and positive charge are sufficiently delocalized over the planar triarylamine scaffolds. The results provide the following insights into the effects of the bridging unit (sulfur vs oxygen) and the dibenzo-annulation on the spin delocalization in the bridged triarylamine radical cations: (1) An effective decrease of the spin density on the nitrogen atom is observed for the sulfur bridge relative to the oxygen bridge; and (2) a moderate decrease of the spin density on the oxygen atom rather than the nitrogen atom is induced by the dibenzo-annulation.

Physalins, including physalins and neophysalins, are a class of highly oxygenated ergostane-type steroids. They are commonly known by the name of 16,24-cyclo-13,14-seco steroids, in which the disconnection of C-13 and C-14 produces an eight or nine-membered ring and the carbocyclization of C-16 and C-24 generates a new six-membered ring. Meanwhile, the oxidation of C-18 methyl to carboxyl group forms a 18,20-lactone, and the oxidation of C-14 and C-17 gets a heterocyclic oxygen acrossing rings C and D. Additionly, physalins frequently form an oxygen bridge to connect C-14 to C-27. Physalins are a kind of characteristic constituents from the species of the genus Physalis (Solanaceae), which are reported with a wide array of pharmacological activities, including anticancer, anti-inflammatory, immunoregulatory, antimicrobial, trypanocidal and leishmanicidal, antinociceptive, antidiabetic and some other activities. Herein,the research progress of physalins from the genus Physalis during the decade from 1970 to 2021 on phytochemistry, pharmacology, pharmacokinetics and application in China are systematically presented and discussed for the first time.

Ciliatasecones A-C (1-3), three rearranged limonoids with a novel ring-seco model and an unprecedented cycle system, were isolated from the root bark of Toona ciliata var. yunnanensis. Ciliatasecones A-B (1-2) share a novel cyclopenta[b]furan ring C/D system through C-9/11-seco and C-11/14 ether linkage. Ciliatasecone C (3) was found to possess a rare rearranged six-membered lactone ring B between C-7 and C-9. Plausible biogenetic pathway speculation indicated that C-9/11 cleavage and oxygen bridge formation played the key roles in the framework rearrangement of 1-3.

Two new highly oxygenated germacranolides, Carpescernolides A (1) and B (2), were isolated from the whole plant of Carpesium cernuum. Their structures were established by extensive analysis of NMR spectra, as well as HRESIMS data. X-ray diffraction studies were used to confirm the absolute configurations of 1 and 2. Notably, compound 1, with an oxygen bridge unit (C-2–O-C-5) and a 4, 8-ketal system at C-8, resulted in a novel type of germacranolide compound. Compound 1 showed a moderate inhibition against SMMC-7721 cancer cells in vitro.

Previously, we have demonstrated the antiadipogenic benefits of Ganoderma triterpenoids (GTs), which indicated GTs have potential therapeutic implications for obesity. In this study, the EtOAc extract of Ganoderma applanatum was further phytochemically investigated for searching new antiadipogenic agents, which led to the isolation of a total of 15 highly oxygenated lanostane triterpenoids, including 9 new compounds (1-9) and 6 known analogues (10-15). Structurally, ganodapplanoic acids A and B (1, 2) are two rearranged 6/6/5/6-fused lanostane-type triterpenoids with an unusual C-13/C-15 oxygen bridge moiety. In addition, the EtOAc extract (GAE) and isolates (1-4,6-15) were assayed for their antiadipogenic effects in 3T3-L1 adipocytes. The results revealed that compound 9 effectively repressed adipogenesis through down-regulating the expression of major proteins (PPARγ, CEBPβ and FAS) involving differentiation and adipogenesis in 3T3-L1 adipocytes. Thus, the present study further demonstrated the antiadipogenic potential of GTs and provided a possible perspective for obesity treatment.

Chemical investigation of a marine-derived Streptomyces sp. KCB-132, cultivated in liquid ISP2 medium, had led to the discovery of three C-ring cleavage angucyclinone N-heterocycles, pratensilins A–C, with a novel spiro indolinone-naphthofuran skeleton. Addition of 50 μM LaCl3 to the same medium and subsequent chemical analysis of this strain returned a new member of this rare class, pratensilin D (1), along with two new angucyclinone derivatives, featuring ether-bridged (2) and A-ring cleavage (3) structural properties. Their structures and absolute configurations were assigned by spectroscopic analysis, single-crystal X-ray diffractions, and equivalent circulating density (ECD) calculations. (+)- and (–)-1, a pair of enantiomeric nitrogen-containing angucyclinones, exhibited different strengths of antibacterial and cytotoxic activities.

Two new dimeric diterpenes, birhodomolleins D ( 1 ) and E ( 2 ), were characterized from the fruits of Rhododendron pumilum . Their structures featured two grayanane diterpenes dimerized through an oxygen bridge locating at C-3 and C-2′. They are the first examples of dimeric grayanane diterpenes with a 3- O -2′ linkage from the Ericaceae family. Their structures were elucidated on the basis of comprehensive analysis of spectroscopic data.

Birhodomolleins A–C ( 1 – 3 ), three novel diterpenoids dimerized from two grayanane diterpenes through an oxygen bridge, were isolated from the flowers of Rhododendron molle . Their structures were elucidated by interpretation of their 1D and 2D NMR and other spectroscopic data. Birhodomollein A ( 1 ) contains a rare chloro-substitution on one of the grayanane moieties. These are the first examples of dimeric diterpenes from the Ericaceae family.

The synthesis of four non-Lowenstein uranyl aluminophosphates, [Cs13Cl5][(UO2)3Al2O(PO4)6], Rb7[Al2O(PO4)3][(UO2)6O4(PO4)2], Cs3[Al2O(PO4)3][(UO2)3O2], and Rb3[Al2O(PO4)3][(UO2)3O2], the first uranyl phosphate salt-inclusion material [Cs4Cs4Cl][(UO2)4(PO4)5], and a related structure Cs4[UO2Al2(PO4)4], all prepared by molten flux methods, is reported. All compounds are discussed from the point of view of their structural features favoring, in some cases, ion-exchange properties. Lowenstein’s rule, well known in the realm of zeolites, aluminosilicate, and aluminophosphate minerals, describes the tendency of tetrahedra (Al, P, Si, and Ge) linked by an oxygen bridge to be of two different elements resulting in the avoidance of Al–O–Al bonds. Zeolites and related aluminosilicate/aluminophosphate minerals are traditionally formed under relatively mild temperatures, where zeolites are synthesized using the hydrothermal synthetic technique. Few exceptions to Lowenstein’s rule are known among aluminophosphates, an...

This study presents comprehensive formation pathways of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) from the pyrolysis of polybrominated diphenyl ethers (PBDEs). A total of 23 PBDE congeners, from mono- to hepta- brominated, were selected to conduct the pyrolysis experiments. The results suggest that n-PBDEs (where n means the number of bromine substituents) can transform into n/(n-1) PBDFs and (n-1)/(n-2) PBDDs as long as they meet certain structural requirement. One single PBDE congener can only transform (if possible) specific PBDF or PBDD based on their specific brominated arrangement by direct/oxygen bridge connecting the two ortho-carbon atoms. Among all selected BDEs, we found that only 2,2',4,4',5,5'-hexaBDE (BDE-153) can transform into 2,3,7,8-tetraBDD, which is most toxic congener among these group of compounds. When the degree of bromination increased, the yield of polybromobenzene increased, while that of the PBDD/Fs decreased, suggesting that the higher PBDEs favors to break the ether bond to form polybromobenzene, while the lower PBDEs favor transformation into PBDD/Fs. We proposed that the results in this study greatly improved our understanding on the transformation of PBDD/Fs from PBDEs in the pyrolysis process.

The seeds of the medicinal plant Caesalpinia sappan yielded fourteen cassane-type diterpenes, including six new rearranged ones named as caesalppans A-F (1-6). Their structures were elucidated by spectroscopic analysis and comparison with literature data. The isolated new compounds 1-6 possess lactone-type cassane diterpenoid skeleton with an oxygen bridge between C-19 and C-20, and were tested cytotoxic activity against four cancer cell lines using the MTT method.

The bis-glyoxylamide peptidomimetics have been synthesized from bis-N-acetylisatins linked at C5 by ring-opening with alcohols, amines, and amino acid methyl ester hydrochlorides. X-ray images of single crystals of bis-glyoxylamide peptidomimetics have been obtained.

Ten undescribed neo-clerodane diterpenoids, named hispanins A-J, together with six known ones, were isolated from the aerial parts of Salvia hispanica L. Their structures were established by extensive spectroscopic analysis. The absolute configurations of the undescribed compounds were determined by the ECD data and single crystal X-ray diffraction analysis. Hispanins B and C represented the first neo-clerodane diterpenoids with a unique oxygen bridge between C-19 and C-20. All isolated compounds were evaluated for their protective effects against H2O2-induced cardiomyocyte injury. Five of these compounds showed significant cardioprotective effects.

Three new Securinega alkaloids, flueggethers B and C (1 and 2) as dimers and flueggether D (3) as a trimer, were isolated from the twigs and leaves of a Chinese herb, Flueggea virosa. Their structures were characterized by spectroscopic means and NMR comparison with known analogues. Among all Securinega alkaloid oligomers reported to date, alkaloids 1 and 2 are rare examples linked via an ether bond, while 3 represents the first member with a mixed oligomerizing pattern incorporating both oxygen bridge and carbon–carbon linkage. An in vitro anti-HIV bioassay revealed moderate activity for 3.

Five new limonoids, named sundarbanxylogranins A-E (1-5), were isolated from the seeds of an Indian mangrove, Xylocarpus granatum, collected from mangrove swamps of the Sundarbans, India. The structures of these limonoids were established by HRESIMS and NMR spectroscopic data. Sundarbanxylogranin A (1) is a rare limonoid containing a bicyclo[5.2.1]dec-3-en-8-one scaffold as the ring A/B-fused core; whereas sundarbanxylogranin B (2) is a typical mexicanolide with an 8α, 30α-epoxy ring. Sundarbanxylogranins C-E (3-5), among which the former two possess a 29-OMe group with different orientation, belong to a small group of limonoids containing a C1-O-C29 oxygen bridge. Sundarbanxylogranin B exhibited moderate anti-HIV activity with an IC50 value of 23.14±1.29μM and a CC50 value of 78.45±1.69μM, respectively.

Worldwide demand has driven the development of hemoglobin (Hb)-based oxygen carriers (HBOCs) as potential acellular oxygen therapeutics. HBOCs have the potential to provide an oxygen bridge to patients and minimize current problems associated with supply and storage of donated blood. However, to date, safety and efficacy issues have hampered the approval of viable HBOCs in the United States. These previous efforts have underscored the need for a better molecular understanding of toxicity to design safe and oxidatively stable HBOCs. Recent Advances: High-resolution accurate mass (HRAM) mass spectrometry (MS) has recently become a versatile tool in characterizing oxidative post-translational modifications that occur in Hb. When integrated with other analytical techniques, HRAM data have been invaluable in providing mechanistic insight into the extent of oxidative modification by quantifying oxidation in amino acids near the reactive heme or at specific "oxidative hotspots."In addition to providing a deeper understanding of Hb oxidative toxicity, HRAM MS studies are currently being used toward developing suitable HBOCs using a "two-prong" strategy that involves (i) understanding the mechanism of Hb toxicity by evaluating mutant Hbs identified in patients with hemoglobinopathies and (ii) utilizing this information toward designing against (or for) these reactions in acellular oxygen therapeutics that will result in oxidatively stable protein.Future HRAM studies are aimed at fully characterizing engineered candidate HBOCs to determine the most oxidatively stable protein while retaining oxygen carrying function in vivo. Antioxid. Redox Signal. 26, 777-793.

Cytochalasins D1 (1) and C1 (2) were isolated from the liquid fermentation of fungus Xylaria cf. curta. Their structures and absolute configurations were determined by comprehensive experimental spectroscopic methods as well as ECD and GIAO 13C NMR calculation. They possess a unique eleven-membered macrocycle with an oxygen bridge. Cytochalasins D1 and C1 showed moderate cytotoxicity against human leukemia cell lines HL-60 with IC50 value of 12.7 and 22.3 μM, respectively.

IrO2 has been investigated as alternative rutile-type catalyst to RuO2 for gas-phase HCl oxidation. The HCl conversion level over IrO2 at 723 K was comparable to that of RuO2 at ca. 170 K lower temperature, in line with the higher computed energy barrier for chlorine evolution over the former oxide. Similarly to RuO2, chlorination took place only at the IrO2 surface, which is predicted to exhibit full occupation of the coordinatively unsaturated iridium sites and replacement of 50% of the oxygen bridge positions by chlorine. Advantageously, IrO2 is more resistant than RuO2 against oxidation, since the latter forms volatile RuO4 species at high temperatures. IrO2 (2 wt %) supported on TiO2-rutile displayed a 6 times higher activity than on TiO2-anatase. Although this corroborates the crucial role of the structural similarity between the carrier and active phase highlighted in the development of RuO2-based catalysts, some differences were uncovered. (i) Small and highly dispersed IrO2 clusters rather than t...

Two new furanoeremophilanes, 1α, 6α-epoxy-9-oxo-10β-hydroxyl-furanoeremophilane (1), and 9-oxo-1α, 6β, 10β-trihydroxy-furanoeremophilane (2) were isolated from Senecio nemorensis. Their structures were elucidated by spectroscopic methods and X-ray crystallography. This is the first report of the isolation of the C1-C6 oxygen bridge of furanoeremophilane. Their cytotoxic effects on BEL7402 and NF-KB cell lines were tested.

Two novel limonoids, named carapanolides A (1) and B (2) were isolated from the seeds of Carapa guianensis AUBLET (Meliaceae), a traditional medicine in Brazil and Latin American countries. Their structures elucidated on the basis of spectroscopic analyses using 1D and 2D NMR techniques were quite unusual, bearing 2,9-oxygen bridge in the 9,10-seco-mexicanolide skeleton. Compound 1 showed moderate activity against L1210 cell line.

Intermolecular hydroalkoxylation of N-allenyl sulfonamides with oximes is achieved under mild gold(I)-catalyzed conditions delivering allyloximino E-enesulfonamides stereoselectively in moderate to high yields. The products contain two important functionalities, imines and enesulfonamides, within one framework containing an oxygen bridge, and the reaction is made possible via a convenient method for conjugated N-sulfonyliminium formation.

Three new Securinega alkaloids, flueggethers B and C (1 and 2) as dimers and flueggether D (3) as a trimer, were isolated from the twigs and leaves of a Chinese herb, Flueggea virosa. Their structures were characterized by spectroscopic means and NMR comparison with known analogues. Among all Securinega alkaloid oligomers reported to date, alkaloids 1 and 2 are rare examples linked via an ether bond, while 3 represents the first member with a mixed oligomerizing pattern incorporating both oxygen bridge and carbon–carbon linkage. An in vitro anti-HIV bioassay revealed moderate activity for 3.

A copper(II) compound ([LCu(μ-OH)CuL(H2O)]ClO4)n (1) [where HL = 2-[(2-dimethylamino-ethylimino)-methyl]-4-nitro-phenol, is a well known Schiff base], has been synthesized and characterized by elemental analysis, IR and UV–Vis spectroscopy and single-crystal X-ray diffraction studies. The compound features a copper(II) polymeric coordination network composed of binuclear species [LCu(μ-OH)CuL(H2O)]+ as building blocks. It crystallizes in monoclinic space group P21/c with cell dimensions a = 22.1453(9), b = 7.8314(3), c = 18.5626(8) and β=108.509(3). The potentially tridentate Schiff base shows a tetra-dentate bonding mode for the 1st time.

To probe the chemical constituents of Patrinia scabra, we undertook the phytochemical investigation on its roots, which led to the isolation and elucidation of three new iridoid glucosides, scabroside A-C (1-3), along with three known iridoids, jatamanin J (4), isopatriscabroside I (5) and loganic acid (6) from the aqueous fraction of the ethanolic extract of the roots. The structures and relative configurations of the three new compounds were elucidated by spectroscopic methods including IR, UV, MS, 1D and 2D NMR experiments. Compound 3 was an unusual iridoid with an oxygen bridge connecting C-3 and C-8.

Godavarin K (1), a new limonoid with an oxygen bridge between C(1) and C(29), was obtained from seeds of an Indian mangrove, Xylocarpus moluccensis, together with a known tetranortriterpene, 6-de(acetyloxy)-7-deacetylchisocheton compound E (=(5α,7α,13α,17α)-7-hydroxy-4,4,8-trimethyl-3-oxocarda-1,14-dienolide; 2). The structure of godavarin K was established on the basis of spectroscopic data. In addition, the confusion of 1H- and 13C-NMR data for compound 2 in previous literature was clarified.

A new guaiane-type sesquiterpene, 4α,7β-dihydroxy-10βH-guai-5-en-1β,8β-endoxide (1), was isolated from Heteropappus altaicus (Compositea). The structure of compound 1, which contains exhibited a rare 1,8-oxide bridge, was established on the basis of spectroscopic data.

A novel and efficient total synthesis of Englerin A is reported. The synthesis featured an intramolecular olefin metathesis ring closure reaction and a highly stereoselective oxygen bridge formation induced by an iodonium ion. This strategy can be used for the synthesis of natural products Englerin A and Englerin B and can provide flexibility in the preparation of various 9-substituted analogues of Englerin A for further structure–activity relationship studies.

Aryloxyphenoxypropionates (APPs) are a class of herbicides targeting acetyl-CoA carboxylase (ACCase) in monocot chloroplast. The article presents the rational design and synthesis of a series of APPs with 2and 4-pyrimidinyloxy moieties. The developed synthetic protocols are versatile and allow convenient functionalization of the phenoxypropionate core with various 2or 4-pyrimidinyl moieties via the oxygen bridge by taking advantage of the reactivity difference between 2-methylsulfonyl and 4-chloro on the pyrimidine ring. Preliminary bioassay shows that most of title compounds have good herbicidal activities against rape and barnyard grass at 100 mg/L. Several compounds are more potent to inhibit the stalk growth of barnyard grass than the commercial herbicide cyhalofop.

1H and 13C Nuclear magnetic resonance spectra of brominated dihydrothebainones, needed for the closure of the oxygen bridge of morphinans to form morphine derivatives, were studied. Bromination of (-)-dihydrothebainone (1) yielded successively 1-bromo-, 1,7α-dibromo-, and 1,5β,7α-tribromo-dihydrothebainone (2,3,4). 1-Bromo-O4-methyldihydrothebainone (12) gave, after bromination, a stable crystalline l,5β,7α-tribromo derivative (15). A 5β,7α-dibromo derivative (9) was formed also starting with l-methyldihydrothebainone (7). Closure of the oxygen bridge in 1,5β,7α-tribromodihydrothebainone (4) in boiling ethanol, yields an equilibrium mixture of 1,7β- and 1,7β-dibromodihydrothebainone (5:6, ∼ 35 : 65). 5β,7α-Dibromo-l-methyldihydrothebainone (9) gave the same result. 13C NMR spectra of the model compounds cyclohexanone, 2-bromo-, 2,2-dibromo-, cis- and trans-2,6-dibromo-cyclohexanone were studied.

A novel trinuclear nickel(II) complex with dissimilar bridges: [Ni3(HL)2(CH3COO)4(CH3OH)2]·2H2O·2CH3OH (1), where H2L = N-(2-hydroxybenzyl)salicylaldimine, has been synthesized and structurally as well as magnetically characterized. Compound 1 has the discrete trinuclear structure, bridged by the phenolic oxygen, a single oxygen and a double oxygen bridge of acetate ions. The magnetic data of complex 1 were analyzed by means of H ˆ = - 2 J ( S ˆ 1 S ˆ 2 + S ˆ 2 S ˆ 3 ) + D [ S ˆ Z 2 - S ( S + 1 ) / 3 ] δ S , S = 3 , leading to J = 4.31 cm−1, g = 2.02, D = 1.22 cm−1.

Six new compounds, phochinenins A–F (1–6), dimerized from 9,10-dihydrophenanthrene and dihydrostilbene through direct coupling or an oxygen bridge, along with eight known compounds, were isolated from the whole plants of Pholidota chinensis. Their structures were elucidated on the basis of extensive spectroscopic investigations (1D-, 2D-NMR, and HR-EI-MS).

A novel taxane with an unprecedented hemiacetal ring between C-13 and C-9 was isolated from the needles of Taxus cuspidata . The structure was characterized as (12αH)-2α,10β-diacetoxy-5α-cinnamoyloxy-9α,13α-epoxytax-4(20)-ene-11β,13β-diol ( 1 ). This is the first example of a natural taxane with a C-13 and C-9 oxygen bridge to form an unusual 6/8/6/6-membered ring system.

Stabilization of peracetic acid (PAA) by aspartic acid diethoxy succinate (AES) was studied by electron spin resonance, UV/Vis spectroscopy, electrospray ionization time-of-flight mass spectrometry and oxygen evolution measurements. The results indicate that Mn(II)-AES complexes may exist in both monomeric and dimeric forms. Dimerization is proposed to proceed via formation of an oxygen bridge between two Mn(II)-AES complexes. The equilibrium between these two forms depends strongly on pH, the monomeric form being favored under acidic conditions, while conditions close to neutral pH favor the dimeric form. In the presence of PAA, the dimer form was oxidized and finally yielded MnO2. Oxygen evolution measurements were carried out to demonstrate the efficiency of AES in stabilizing PAA solutions containing small amounts of Mn(II) impurities under acidic conditions.

Xylogranatin E, the second phragmalin with a rare oxygen bridge between C1 and C29 found in nature, was isolated from the fruit of a Chinese mangrove, Xylocarpus granatum. Its structure was determined by spectroscopic analysis. Complete assignment of 1H and 13C NMR data of xylogranatin E was achieved by 2D NMR techniques, including 1H-1H COSY, HSQC, HMBC and NOESY spectra.

The syntheses of 1∶1‐macrocycles 3 (n=1), unsymmetrical macrocycle 5 (m=0, n=1), 2∶2‐macrocycle 5 (m=n=1 and 2), 3∶3 macrocycle 7, and several open‐chain ethereal compounds prepared from 2,5‐dichloro‐1,3,4‐thiadiazole 1 and various polyethylene glycols dianions are described. Structural proofs are afforded by their mass and NMR spectral features. The quaternization studies of a few macrocycles with methyl iodide at elevated temperature furnished a diketo derivative 8 through a facile Hilbert–Johnson reaction.