Octane Unit Research Articles

Anti-diabetic and anti-inflammatory indole diterpenes from the marine-derived fungus Penicillium sp. ZYX-Z-143

Seven new indole-diterpenoids, penpaxilloids A–E (1–5), 7-methoxypaxilline-13-ene (6), and 10-hydroxy-paspaline (7), along with 20 known ones (8–27), were isolated from the marine-derived fungus Penicillium sp. ZYX-Z-143. Among them, compound 1 was a spiro indole-diterpenoid bearing a 2,3,3a,5-tetrahydro-1H-benzo[d]pyrrolo[2,1–b][1,3]oxazin-1-one motif. Compound 2 was characterized by a unique heptacyclic system featuring a rare 3,6,8-trioxabicyclo[3.2.1]octane unit. The structures of the new compounds were established by extensive spectroscopic analyses, NMR calculations coupled with the DP4 + analysis, and ECD calculations. The plausible biogenetic pathway of two unprecedented indole diterpenoids, penpaxilloids A and B (1 and 2), was postulated. Compound 1 acted as a noncompetitive inhibitor against protein tyrosine phosphatase 1B (PTP1B) with IC50 value of 8.60 ± 0.53 μM. Compound 17 showed significant α-glucosidase inhibitory activity with IC50 value of 19.96 ± 0.32 μM. Moreover, compounds 4, 8, and 22 potently suppressed nitric oxide production on lipopolysaccharide-stimulated RAW264.7 macrophages.

Synthesis of Unusual Amino Acid Derivatives Containing Bicyclo[2.2.2]octane Unit by the Diels‐Alder Approach Involving Pentacene

AbstractHere, we report various unusual amino acid derivatives containing bicyclo[2.2.2]octane unit through the Diels‐Alder (DA) reaction as a key step. DA reaction was carried out with pentacene as a diene and different dinenophiles used here are derived by dehydration of serine derivatives.

Supramolecular Polymerization Powered by Escherichia coli : Fabricating a Near-Infrared Photothermal Antibacterial Agent in Situ

Supramolecular Polymerization Powered by <i>Escherichia coli</i> : Fabricating a Near-Infrared Photothermal Antibacterial Agent in Situ

Application of Polyamines and Amino Acid Derivatives Based on 2-Azabicycloalkane Backbone in Enantioselective Aldol Reaction.

Carbon–carbon bond forming reactions, such as aldol reaction and condensation, belong to extremely desired transformations as manifested by >25,000 entries in SciFinder. Their stereoselective variant requires the use of an appropriate catalyst with a strictly defined structure. Hence, chiral 2-azabicycloalkane-based catalysts were designed, synthesized and tested in a stereoselective aldol reaction between cyclic/acyclic ketone and p-nitrobenzaldehyde both in organic and aqueous media. Among catalysts containing a chiral bicyclic backbone, amide based on 2-azabicyclo[3.2.1]octane and pyrrolidine units showed the best catalytic activity and afforded aldol product in excellent chemical yields (up to 95%) and good diastereo- and enantioselectivity (dr 22:78, ee up to 63%).

Coordination Behavior of a P4 -Butterfly Complex towards Transition Metal Lewis Acids: Preservation versus Rearrangement.

The reactivity of the P4 butterfly complex [{Cp’’’Fe(CO)2}2(μ,η1:1‐P4)] (1, Cp’’’=η5‐C5H2 tBu3) towards divalent Co, Ni and Zn salts is investigated. The reaction with the bromide salts leads to [{Cp’’’Fe(CO)2}2(μ3,η2:1:1‐P4){MBr2}] (M=Co (2Co), Ni (2Ni), Zn (2Zn)) in which the P4 butterfly scaffold is preserved. The use of the weakly ligated Co complex [Co(NCCH3)6][SbF6]2, results in the formation of [{(Cp’’’Fe(CO)2)2(μ3,η4:1:1‐P4)}2Co][SbF6]3 (3), which represents the second example of a homoleptic‐like octaphospha‐metalla‐sandwich complex. The formation of the threefold positively charged complex 3 occurs via redox processes, which among others also enables the formation of [{Cp’’’Fe(CO)2}4(μ5,η4:1:1:1:1‐P8){Co(CO)2}][SbF6] (4), bearing a rare octaphosphabicyclo[3.3.0]octane unit as a ligand. On the other hand, the reaction with [Zn(NCCH3)4][PF6]2 yields the spiro complex [{(Cp’’’Fe(CO)2)2(μ3,η2:1:1‐P4)}2Zn][PF6]2 (5) under preservation of the initial structural motif.

Paliasanines A-E, 3,4-Methylenedioxyquinoline Alkaloids Fused with a Phenyl-14-oxabicyclo[3.2.1]octane Unit from Melochia umbellata var. deglabrata.

Five new quinoline alkaloids, paliasanines A-E (1-5), and 17 known compounds (6-22) were isolated from a methanol extract of Melochia umbellata var. deglabrata leaves. Their chemical structures were elucidated by analysis of HRMS and 1D and 2D NMR spectroscopic data. Compounds 1-5 are the first naturally occurring 3,4-methylenedioxyquinolines incorporating an oxabicyclo[3.2.1]octane unit. Compounds 6 and 7 displayed selective cytotoxicity (IC50 5.9-8.4 μM) against A549 and MCF-7 cell lines, while compounds 1-5 were not active. Compounds 1-3 did not exhibit an anti-HIV effect in MT4 cells, although the related quinolone derivative waltherione A exhibited significant activity. These preliminary results indicate that the 3-methoxy-4-quinolone skeleton might be preferred for both antiproliferative and anti-HIV activities.

Effect of gasoline composition on the absorption and retention of fuel vapor by activated carbon of the automobile adsorber

The physicochemical characteristics of petrol samples are studied. It is established that the fuel purchased at fuel stations corresponds to the standard parameters presented in the EURO standard for unleaded petrol. The presence of saturated hydrocarbons in petrol is determined using concentrated sulfuric acid, which reacts with unsaturated (alkenes, olefins) and aromatic hydrocarbons, without reacting with saturated hydrocarbons. The fractional composition of petrol samples is determined from the distillation temperatures measured by a mercury thermometer included in the automatic oil distillation apparatus ARNS-1E, acidity titration with an alcohol solution of potassium hydroxide gasoline mixtures with 80% ethanol. An acid-base phenolphthalein indicator (pH = 8.0-9.6) is used to indicate an excess of OH−. The density of the fuel samples is measured with oleometers (densimeters), octane numbers (ON) - indicator (Octanometer) OKTAN-IM. The limit of the permissible absolute error of the measurement of ON is ± 2 octane units. It is established that all petrols without exception contain saturated, unsaturated and aromatic hydrocarbons. It is shown that of the seven samples studied, two samples have some peculiarities. It is concluded that when controlling the quality of fuel, it is necessary to take into account not only the conformity of the determined value to the parameter of the norm, but also the differences in the values of the indices obtained when testing a series of fuel samples.

Hawaiienols A-D, Highly Oxygenated p-Terphenyls from an Insect-Associated Fungus, Paraconiothyrium hawaiiense.

Four new highly oxygenated p-terphenyls, hawaiienols A-D (1-4), have been isolated from cultures of Paraconiothyrium hawaiiense, a fungus associated with the Septobasidium-infected insect Diaspidiotus sp.; their structures were elucidated primarily by NMR experiments. The absolute configurations of 1 and 2-4 were assigned by single-crystal X-ray diffraction analysis using Cu Kα radiation and via electronic circular dichroism calculations, respectively. Compound 1 incorporated the first naturally occurring 4,7-dioxatricyclo[3.2.1.03,6]octane unit in its p-terphenyl skeleton and showed cytotoxicity toward six human tumor cell lines.

Inter- and Intramolecular [4+2]-Cycloaddition Reactions with 4,4-Disubstituted N-Silyl-1,4-dihydropyridines as Precursors for N-Protonated 2-Azabutadiene Intermediates

An efficient and straightforward method for the synthesis of polycyclic ring systems with a central 2-azabicyclo[2.2.2]octane unit is developed. The process is based on [4+2]-cycloaddition reactions that are performed with N-protonated 2-azabutadiene intermediates as heterodienes, generated from 4,4-disubstituted <i>N</i>-silyl 1,4-dihydropyridines. As dienophiles, cyclopentadiene for the intermolecular cycloaddition and an allyl moiety already attached to the 4,4-disubstituted 1,4-dihydropyridines for the intramolecular variant, are used.

Siladenoserinols A–L: New Sulfonated Serinol Derivatives from a Tunicate as Inhibitors of p53–Hdm2 Interaction

Siladenoserinols A-L were isolated from a tunicate as inhibitors of p53-Hdm2 interaction, a promising target for cancer chemotherapy. Their structures including the absolute configurations were elucidated to be new sulfonated serinol derivatives, each of which contains a 6,8-dioxabicyclo[3.2.1]octane unit and either glycerophosphocholine or glycerophosphoethanolamine moiety. They inhibited p53-Hdm2 interaction with IC(50) values of 2.0-55 μM. Among them, siladenoserinol A and B exhibited the strongest inhibition with an IC(50) value of 2.0 μM.

New Fluorine Substituted Liquid Crystal Containing Bicyclo[2.2.2]Octane Unit

We have designed and synthesized a new series of liquid crystalline compounds with hybridized three-ring system based on bicyclo[2.2.2]octane unit together with fluorine substituted phenyl and biphenyl fragments. The key stages of the synthesis are alkylation of substituted benzene in concentrated sulfuric acid by bicyclo[2.2.2]octanoles and further cross-coupling between 3,4-difluorophenylboronic acid and the alkylation product. The influence of bicyclo[2.2.2]octane unit position in mesogenic core and fluorine substituents onto a phase transitions of the liquid crystals is discussed.

Extending Pummerer Reaction Chemistry: Application to the Assembly of the Pentacyclic Core of Dibromopalau’amine

A pentacyclic model system featuring the trans azabicyclo[3.3.0]octane unit of dibromopalau'amine was prepared with complete diastereoselectivity in the polycyclic core from a tricyclic precursor. The key transformations of this sequence include (a) a Pummerer reaction-mediated oxidative bicyclization, and (b) a Wolff rearrangement-based ring contraction to deliver the strained azabicyclo[3.3.0]octane core.

ChemInform Abstract: Epoxides in Synthesis. Synthesis of the Novel 2,6-Dioxabicyclo(3.2.1) octane Units in the Citreoviridinols and the Aurovertins.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Mechanical aspects of molecular rods

The mechanical response of three types of molecular rods to various loads was computationally examined. These involved stretching, compression and several modes of bending. The rods studied were (i) polyynes ranging from C 4 to C 20 ( 1), (ii) [2]-[4]staffanes ( 2) and (iii) short oligomers consisting of the bicyclo[2.2.2]octane unit ( 3). In spite of the inhomogeneity of the rods, a good to excellent compliance with the laws of mechanical engineering was obtained. Thus, all three systems obeyed Hook’s law for the serial combination of individual springs. Upon compression the force – first derivative of the energy with respect to the displacement – increases linearly until buckling of the rod is reached. The critical buckling point shows a very good correlation with the inverse square of the length of the rod. In the compression mode, the rod acquires the shape of the sine function, as expected.

3α-Hydroxy-ent-atis-16-en-14-one

The title compound, C20H30O2, is an ent-atisane diterpenoid which was isolated from the roots of Euphorbia kansuensis. The mol­ecule contains five six-membered rings, among which three six-membered rings of the bicyclo­[2.2.2]octane unit adopt boat conformations and two cyclo­hexane rings adopt chair conformations. In the crystal structure, mol­ecules are connected by inter­molecular O—H⋯O hydrogen bonds, forming zigzag chains propagating parallel to [001].

Atropurpuran, a novel diterpene with an unprecedented pentacyclic cage skeleton, from Aconitum hemsleyanum var. atropurpureum

A novel diterpene with an unprecedented pentacyclic skeleton, designated as atropurpuran ( 1), featuring a unique motif to fuse two bicyclo[2.2.2]octane units, was isolated from the roots of Aconitum hemsleyanum var. atropurpureum. Its structure and relative configuration were established by NMR techniques and single-crystal X-ray diffraction. The biosynthetic origin of 1 was proposed to be Hetidane-type diterpenoid.

Di-tert-butylN,N′-(octahydropentalene-2,5-diyl)dicarbamate

In the molecule of the title compound, C18H32N2O4, the central bicyclo­[3.3.0]octane (octa­hydro­penta­lene) has a rigid ring junction. Both rings of the bicyclo­[3.3.0]octane unit adopt an envelope conformation, and the flexible tert-butyl­carbamoyl side chains each have an extended conformation. Such a constrained bicyclo­[3.3.0]octane aliphatic template is of inter­est with respect to the design of novel self-assembling motifs. Mol­ecules related by c-glide symmetry are linked via inter­molecular N—H⋯O hydrogen bonds, forming a two-dimensional layer structure. Neighboring layers are weakly associated along the a axis due to the close approach of the tert-butyl­carbamoyl groups (2.55 Å).

Self-assembly multilayer of photochromic bolaform spiroxazine

A novel, bolaform spiroxazine in which the hydrophobic chain comprised a hexamethylene unit and a 1,4-diazabicyclo[2,2,2]octane unit was synthesized. Alternate multilayer films of the spiroxazine and polystyrenesulfonate (PSS) were prepared using layer-by-layer deposition. UV–vis absorbance measurements revealed that the bilayer deposition process was linear and highly reproducible. The photoinduced ionic conductivity response of the SO/PSS multilayer was also studied.

(3Z)-2-Benzyl-3-benzylidene-6-phenyl-2-azabicyclo[2.2.2]octan-5-one

In the title compound, C27H25NO, all three rings in the azabicyclo[2.2.2]octane unit adopt a boat conformation. An intermolecular C—H...O interaction forms a characteristic R 2 2(14) motif dimer in the crystal packing.

Total Synthesis of (.+‐.)‐13‐Methoxy‐15‐oxozoapatlin, a Rearranged Kaurane Diterpenoid.

A 21-step linear synthesis of the structurally novel and biologically intriguing diterpenoid (±)-13-methoxy-15-oxozoapatlin (6) is described. Of particular note in this work is the development of a new method for the construction of the functionalized bicyclo[3.2.1]octane unit present in the target substance.