Etude des petits cycles—XXXVII: Syntheses et proprietes spectrales du tetracyclopropylidene ([4]rotane) et des composes polycyclopropylspiraniques de la serie

The syntheses of [4]rotane and polycyclopropylspiranic derivatives are reported. One route involves the formation of cyclopropane rings from C₄-acyloins; a second route uses the dimerisation of bicyclopropylidene. Spectroscopic data do not point to any particular electronic interactions between cyclopropane rings in these compounds.     

Diastereoselective, large scale synthesis of β-amino acids via asymmetric enamide hydrogenation as α2δ ligands for the treatment of generalized anxiety disorder and insomnia

The syntheses of β-amino acids 1 and 2 are presented by means of an alternative route to the asymmetric Michael-addition route reported in the preceding article. These two compounds, which bind to the α2δ subunit of calcium channels and have important medical applications, have been prepared on multi-kilogram scale in our pilot plant through a new approach that introduces the chirality at the β-carbon via asymmetric hydrogenation of an enamide precursor. Two Rh-based catalysts, (R)-mTCFP-Rh(COD)BF₄ and (R)-binapine-Rh(COD)BF₄, were found to be superior in this transformation and gave very high diastereoselectivities. The process development for catalyst selection is described.     

Ionic liquid enabled sulfamoylation of arenes: an ambient, expeditious and regioselective protocol for aryl sulfonamides

The ionic liquid, 1-butyl-3-methylimidazolium chloroaluminate, [bmim]Cl·AlCl₃, N=0.67 mediated syntheses of aromatic sulfonamides via electrophilic substitution of arenes is reported. The protocol serves as a distinctly expeditious and ambient route towards the syntheses of these pharmaceutically useful compounds, yielding quantitative conversions at room temperature within 5-30 min in most of the cases. The Lewis acidity and molar stoichiometry of the ionic liquid influences the extent of conversion. The method has been used for the syntheses of a diverse range of sulfonamides by variation of arenes and sulfamoyl chlorides. With monosubstituted benzenes, the protocol offers an added advantage of exclusive selectivity towards the formation of para substituted sulfonamides over the ortho products.     

Synthesis and Pharmacological Evaluation of Chlorinated N-Alkyl-3- and -5-(2-hydroxyphenyl)pyrazoles as CB1 Cannabinoid Ligands

The syntheses of several new 3- and 5-(4-chloro-2-hydroxyphenyl)-5- and -3-(2,4-dichlorophenyl)-1-alkylpyrazoles are reported. These syntheses started from simple chlorophenols, 2,4-dichlorobenzaldehyde or ethyl 2,4-dichlorobenzoate in order to prepare pyrazoles bearing three and four chloro substituents in certain positions. The affinity of these compounds towards the CB ₁ type cannabinoids receptors was then evaluated in human brain tissues (frontal cortex). The results showed that some of the compounds exhibit affinity towards this kind of receptors in the micromolar range.     

Synthesis and Pharmacological Evaluation of Chlorinated <Emphasis Type="Italic">N</Emphasis>-Alkyl-3- and -5-(2-hydroxyphenyl)pyrazoles as <Emphasis Type="Italic">CB</Emphasis><Subscript>1</Subscript> Cannabinoid Ligands

Summary. The syntheses of several new 3- and 5-(4-chloro-2-hydroxyphenyl)-5- and -3-(2,4-dichlorophenyl)-1-alkylpyrazoles are reported. These syntheses started from simple chlorophenols, 2,4-dichlorobenzaldehyde or ethyl 2,4-dichlorobenzoate in order to prepare pyrazoles bearing three and four chloro substituents in certain positions. The affinity of these compounds towards the CB ₁ type cannabinoids receptors was then evaluated in human brain tissues (frontal cortex). The results showed that some of the compounds exhibit affinity towards this kind of receptors in the micromolar range.     

Biomimetic total synthesis of malbrancheamide and malbrancheamide B

The biomimetic total syntheses of both malbrancheamide and malbrancheamide B are reported. The synthesis of the two monochloro species enabled the structure of malbrancheamide B to be unambiguously assigned. The syntheses each feature an intramolecular Diels-Alder reaction of a 5-hydroxypyrazin-2(1H)-one to construct the bicyclo[2.2.2]diazaoctane core, which has also been proposed as the biosynthetic route to these compounds.     

A practical approach to the synthesis of insect antifeedant tonghaosu analogs

Tonghaosu and its analogs are a class of structurally interesting spiroketal enol‐ether compounds. A practical route to furandiol, a key intermediate for their syntheses, was developed. Using Friedel‐Crafts benzoylation of 3‐(2‐fury I) propyl acetate, a diarylketone was obtained in high yield, which was further transformed into corresponding furandiol by reduction with NaBH₄ in basic medium with simultaneous ester hydrolysis. The furandiol was then cyclized into the desired spiroketal enol‐ether compound in the presence of CuSO₄ 5H₂O.     

A General,Concise Strategy that Enables Collective Total Syntheses of over 50 Protoberberine and Five Aporhoeadane Alkaloids within Four to Eight Steps

A concise, catalytic, and general strategy that allowed efficient total syntheses of 22 natural 13‐methylprotoberberines within four steps for each molecule is reported. This synthesis represents the most efficient and shortest route to date, featuring three catalytic processes: CuI‐catalyzed redox‐A³ reaction, Pd‐catalyzed reductive carbocyclization, and PtO₂‐catalyzed hydrogenation. Importantly, this new strategy to the tetracyclic framework has also been applied to the collective concise syntheses of >30 natural protoberberines (without 13‐methyl group) and five aporhoeadane alkaloids.     

Solvent‐Free Syntheses of Hierarchically Porous Aluminophosphate‐Based Zeolites with AEL and AFI Structures

Development of sustainable routes for synthesizing aluminophosphate‐based zeolites are very important because of their wide applications. As a typical sustainable route, solvent‐free synthesis of zeolites not only decreases polluted wastes but also increases product yields. Systematic solvent‐free syntheses of hierarchically porous aluminophosphate‐based zeolites with AEL and AFI structures is presented. XRD patterns and SEM images show that these samples have high crystallinity. N₂ sorption isotherm tests show that these samples are hierarchically porous, and their surface areas are comparable with those of corresponding zeolites from hydrothermal route. Chosen as an example, catalytic oxidation of ethylbenzene with O₂ shows that cobalt substituted APO‐11 from the solvent‐free route (S‐CoAPO‐11) is more active than conventional CoAPO‐11 from hydrothermal route owing to the sample hierarchical porosity.     

Assembly of 3D Coordination Polymers from 2D Sheets by [2+2] Cycloaddition Reaction

The synthesis of three 2D interdigitated Zn^II coordination polymers (CPs), by using three monotopic ligands containing C?C bonds, is reported. Among these, two CPs with 4spy (4‐styryl pyridine) and 2F‐4spy (a 2′‐fluoro derivative of 4spy) ligands showed quantitative formation of cyclobutane rings, thus demonstrating a unique synthetic procedure to synthesize metal–organic frameworks (MOFs) by using this photochemical reaction. Interestingly, these compounds can also be synthesized by mechanochemical grinding procedures by using Zn(OAc)₂. In contrast, Zn(NO₃)₂ did not yield the required product, unlike in the solution route. In addition, compounds with 4vpy (4‐vinylpyridine), 4spy and 2F‐4spy ligands created different units in the CPs; 4vpy and 2F‐4spy furnished paddle wheel units, whereas 4spy yielded tetrahedral Zn^II repeating units. Furthermore, the change in coordination geometry manifests in the photoluminescence properties, attributed to the difference in charge‐transfer and ligand‐centered fluorescent phenomenon.     

Synthesis of 3,3-Dimethylenedithio-5-oxyaldehydes

The syntheses of 3,3-dimethylenedithioaldehydes carring a CO₂R, OTHP or OAc group at the ω-position in lineal five-carbon chains are reported. The dithiolane group makes these compounds substitutes of the corresponding unstable β-ketoaldehydes as synthetic five-carbon building blocks.     

Zinc(II) and cadmium(II) complexes of Schiff bases derived from amino acids and pyridine-3-carboxaldehyde: synthesis,crystal structures,and fluorescence

Two d¹⁰ Schiff-base complexes, Zn₂(L₁)₂(H₂O)₆ ? SO₄ (1) and Cd(L₂)₂(H₂O)₄ (2) [HL₁ = 3-((pyrid-3-yl)-methylene)aminobenzoic acid; HL₂ = 4-((pyrid-3-yl)-methylene)aminobenzoic acid], have been synthesized and structurally characterized by elemental analyses, FT-IR spectra, and thermal studies, as well as single crystal X-ray diffraction. Complex 1 is a dinuclear macrocyclic structure with 22-membered rings and is assembled into a 3-D sandwich supramolecular network motif through H-bonding interactions; 2 is a mononuclear structure and is interlinked through H-bonding and π ··· π stacking contacts to generate another 3-D supramolecular network. Furthermore, fluorescent properties of the two complexes are also reported.     

Short total syntheses of the avenaciolide family of natural products

The avenaciolide family of natural products are small α-methylene bis-γ-lactones that exhibit a wide variety of biological activities. Herein we report concise syntheses of five members of this family of natural products along with the synthesis of one non-natural analogue. The syntheses proceed in five or six steps from simple, commercially available compounds and feature a key oxidative cyclization/lactonization reaction that likely occurs via a radical mechanism.     

New Aquapentachlorochromate(III) Compounds: K2[CrCl5(H2O)] and (NH4)2[CrCl5(H2O)]

Synthesis and crystal structures of two new compounds, K₂[CrCl₅(H₂O)] ( I ) and (NH₄)₂[CrCl₅(H₂O)] ( II ) are reported. Both compounds were prepared from chromium(VI) salts by two different methods and reaction pathways of these syntheses are suggested. The crystal structures of these two aquapentachlorochromates(III) have been determined from three dimensional X‐ray data collected at low temperature, 173 K. The two structures are isomorphous and their unit cell dimensions are quite similar. They are orthorhombic, space groups Pnma, with Z = 4. Both structures are composed of [CrCl₅(H₂O)]^2? units held together by the counterion framework. The coordination around the chromium ion deviates from a regular octahedron due to the shorter equatorial chromium‐oxygen bond.     

The preparation of di-t-butyl ditelluride and di-t-butyl telluride and the 125te NMR and Mössbauer spectra of some dialkyl tellurides and ditellurides

The synthesis of di-t-butyl ditelluride, t-Bu₂Te₂, and di-t-butyl telluride, t-Bu₂Te, are reported together with that of di-(neo-hexyl) ditelluride. New syntheses of Me₂Te₂ and i-Pr₂Te₂ are presented. The high resolution ¹²⁵Te NMR data and the Mössbauer data for these compounds are discussed. The use of tellurium-proton couplings in high resolution ¹²⁵Te NMR spectra in assigning the resonances in mixed dialkyl ditellurides is also illustrated.     

Synthesis of heterocycles using products of the addition of polyhaloalkanes to unsaturated systems. 5. Synthesis of substituted thiazoles

First syntheses are reported for 2-aminothiazoles, 2-chlorothiazoles, and 2-thiazolones with a 2,2,-trichloroethyl group at C₍₅₎ using the products of the homolytic addition of CCl₄ and trichloroacetonitrile to methyl vinyl ketone. Further transformation of this substituent may be carried out for the preparation of compounds with possible biological activity.For communication 4, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1120–1124, August, 1993.     

Characterization of the first mixed-valent liquid-crystalline materials. Synthesis and structural properties of new binuclear ruthenium carboxylates

Abstract

The syntheses and structural properties of new binuclear ruthenium (II, III) complexes with long chain carboxylates, of general formula Ru₂(RCO₂)₄X (R = C₈H₁₇, C₁₁H₂₃ and X = C1, RCOO), are reported. The thermodynamic behaviour of these compounds is strongly influenced by the nature of the counterion X. The chloro complexes (X = CI) are not mesomorphic whereas the carboxylato species (X = RCOO) are shown to exhibit a thermotropic columnar mesophase, thus providing the first example of a mixed-valent liquid-crystalline material.     

Synthese von 2-Hydeoxy-3-methyl-2-hexen-4-olid

Synthesis of 2-Hydroxy-3-methyl-2-hexen-4-olid The title compound 13a, a substance used in food-flavoring, was synthesized in 89% overall yield, starting from methyl 2-hydeoxy-3-butenoate (3_a). The key step in this transformation is the isomerization of the C?C bond in 3_a which yielded methyl 2-oxobutanoate as an intermediate. The latter underwent a self-condensation yielding 2-hydroxy-4-(methoxycarbonyl)-3-methyl-2-hexen-4-olid ( 11 _a), which, after hydrolysis and decarboxylation, gave 13 _a. In addition, the syntheses of five other compounds related to 13 _a are reported.     

A [3+2] dipolar cycloaddition route to 3-hydroxy-3-alkyl oxindoles: an approach to pyrrolidinoindoline alkaloids

A [3 + 2] cycloaddition approach to the 3-hydroxy-3-alkyl oxindole scaffold is described. Isoxazolines obtained by cycloaddition of nitrile oxide 3 with 3-methylene oxindoles were elaborated to 3-hydroxy-3-cyanomethyl oxindoles employing a one-pot protocol en route to the pyrrolidinoindoline moiety which is found in many natural products. The total syntheses of alkaloids (±)-alline and (±)-CPC-1 were achieved using this methodology.     

Hydrogen–Deuterium Exchange Reactions of Aromatic Compounds and Heterocycles by NaBD4‐Activated Rhodium,Platinum and Palladium Catalysts

Conventional thermal and microwave conditions were compared for hydrogen–deuterium (H/D) exchange reactions of aminobenzoic acids catalysed by NaBD₄‐activated Pd/C or RhCl₃ with D₂O as the deuterium source. We also investigated different NaBD₄‐activated metal catalysts (including Pd/C, RhCl₃ and Pt/C) under microwave conditions for an efficient H/D exchange of aromatic and heterocyclic compounds. Even higher deuterium incorporations were obtained for Pd/C and Pt/C catalyst mixtures due to the previously observed synergistic effect. Finally, we have applied these optimised conditions for one‐step syntheses of the MS standards of several pharmaceutically active compounds.