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An optimized method for synthesis and purification of 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN).

ABSTRACT: 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN), an aroma compound present in wine, is used for sensory and physicochemical analyses. Therefore, synthesis of TDN of high purity is required for these purposes. Optimization of TDN synthesis in order to facilitate its subsequent purification was described. As a result, ?99.5 % of TDN purity was reached.•The possibility of using both ?-ionone and ?-ionone as starting substances was demonstrated•Modifications of the use of reagents in the second and third steps of TDN synthesis were proposed

SUBMITTER: Dobrydnev A

PROVIDER: S-EPMC6938800 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Target-Guided Isolation of Progenitors of 1,1,6-Trimethyl-1,2-dihydronaphthalene (TDN) from Riesling Wine by High-Performance Countercurrent Chromatography.

Project description:High-performance countercurrent chromatography (HPCCC) was used for the target-guided isolation of precursors of 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) from Riesling wine. In separated HPCCC fractions of an Amberlite® XAD®-2 extract obtained from a German Riesling, TDN-generating fractions were identified by the acid-catalyzed hydrolysis of the progenitors at pH 3.0 and subsequent HS-GC-MS/MS analysis. The presence of multiple TDN-generating precursors in Riesling wine could be confirmed. From polar HPCCC fractions (11-13 and 14-16), 3,4-dihydroxy-7,8-dihydro-β-ionone 3-O-rutinoside and 3,4-dihydroxy-7,8-dihydro-β-ionone 3-O-β-d-glucopyranoside were isolated as major TDN-precursors at a sufficient amount for structure elucidation by NMR spectroscopic studies. In the medium polar HPCCC factions (27-35), enzymatic hydrolysis liberated the aglycones 3-hydroxy-β-ionone and 3-hydroxy-TDN in minor amounts. In further less polar TDN-generation fractions (36-44 and 45-50), glycosidic progenitors were absent; instead, a minor TDN formation most likely from non-conjugated constituents was observed.

| S-EPMC9458034 | biostudies-literature

Enantioselective synthesis of 1,2-dihydronaphthalene-1-carbaldehydes by addition of boronates to isochromene acetals catalyzed by tartaric acid.

Project description:Tartaric acid is an ideal asymmetric catalyst as it is abundant, cheap, and environmentally friendly. (+)-Tartaric acid was found to catalyze a novel enantioselective [4 + 2] cycloaddition of isochromene acetals and vinylboronates. A variety of substituted isochromene acetals were tolerated, furnishing the desired dihydronaphthalenes and dihydrobenzofluorene products in good yields. High enantiomeric ratios (up to 98.5:1.5) and excellent diastereoselectivities (all >99:1) were observed employing 10 mol % of (+)-tartaric acid as the catalyst, in combination with 5 mol % of Ho(OTf)3.

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(1,2-Dicarba-closo-dodeca-boran-yl)trimethyl-methanaminium iodide.

Project description:The title compound, [1-(CH(3))(3)NCH(2)-1,2-C(2)B(10)H(11)](+)·I(-) or C(6)H(22)B(10)N(+)·I(-), was obtained by the reaction of (1,2-dicarba-closo-dodeca-boran-yl)dimethyl-methanamine with methyl iodide. The asymmetric unit contains two iodide anions and two (o-carboran-yl)tetra-methyl-ammonium cations. The bond lengths and angles in the carborane cage are within normal ranges, but the N-C(methyl-ene)-C(cage) angle is very large [120.2?(2)°] because of repulsion between the carborane and tetra-methyl-ammonium units. In the crystal, ions are linked through C-H?I hydrogen bonds.

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1,2-Bis{2-[2-(trimethyl-sil-yl)ethyn-yl]phen-yl}ethane-1,2-dione.

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Catalytic 1,2-dihydronaphthalene and E-aryl-diene synthesis via CoIII-Carbene radical and o-quinodimethane intermediates.

Project description:Catalytic synthesis of substituted 1,2-dihydronaphthalenes via metalloradical activation of o-styryl N-tosyl hydrazones ((E)-2-(prop-1-en-1-yl)benzene-N-tosyl hydrazones) is presented, taking advantage of the intrinsic reactivity of a cobalt(iii)-carbene radical intermediate. The method has been successfully applied to a broad range of substrates with various R1 substituents at the aromatic ring, producing the desired ring products in good to excellent isolated yields for substrates with an R2 = COOEt substituent at the vinylic position (∼70-90%). Changing the R2 moiety from an ester to other substituents has a surprisingly large influence on the (isolated) yields. This behaviour is unexpected for a radical rebound ring-closure mechanism, and points to a mechanism proceeding via ortho-quinodimethane (o-QDM) intermediates. Furthermore, substrates with an alkyl substituent on the allylic position reacted to form E-aryl-dienes in excellent yields, rather than the expected 1,2-dihydronaphthalenes. This result, combined with the outcome of supporting DFT calculations, strongly points to the release of reactive o-QDM intermediates from the metal centre in all cases, which either undergo a 6π-cyclisation step to form the 1,2-dihydronaphthalenes, or a [1,7]-hydride shift to produce the E-aryl-dienes. Trapping experiments using TEMPO confirm the involvement of cobalt(iii)-carbene radical intermediates. EPR spectroscopic spin-trapping experiments using phenyl N-tert-butylnitrone (PBN) confirm the radical nature of the catalytic reaction.

| S-EPMC5857932 | biostudies-literature

Dimethyl 2,6,8-trimethyl-1,2-dihydroquinoline-2,4-dicarboxylate.

Project description:The title compound, C(16)H(19)NO(4), the hydrogenated ring adopts a twisted conformation. In the crystal, inter-molecular C-H?O hydrogen bonds link the mol-ecules into centrosymmetric R(2) (2)(10) dimers. These dimers are further connected via inter-molecular N-H?O hydrogen bonds, forming infinite double chains along [001].

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Optimized synthesis of luminescent silica nanoparticles by a direct micelle-assisted method.

Project description:Silica nanoparticles (NPs) are versatile nanomaterials, which are safe with respect to biomedical applications, and therefore are highly investigated. The advantages of NPs include their ease of preparation, inexpensive starting materials and the possibility of functionalization or loading with various doping agents. However, the solubility of the doping agent(s) imposes constraints on the choice of the reaction system and hence limits the range of molecules that can be included in the interior of NPs. To overcome this problem, herein, we improved the current state of the art synthetic strategy based on Pluronic F127 by enabling the synthesis in the presence of large amounts of organic solvents. The new method enables the preparation of nanoparticles doped with large amounts of water-insoluble doping agents. To illustrate the applicability of the technology, we successfully incorporated a range of phosphorescent metalloporphyrins into the interior of NPs. The resulting phosphorescent nanoparticles may exhibit potential for biological oxygen sensing.

| S-EPMC6739172 | biostudies-literature

Optimized DNA extraction and purification method for characterization of bacterial and fungal communities in lung tissue samples.

Project description:Human lungs harbor a scarce microbial community, requiring to develop methods to enhance the recovery of nucleic acids from bacteria and fungi, leading to a more efficient analysis of the lung tissue microbiota. Here we describe five extraction protocols including pre-treatment, bead-beating and/or Phenol:Chloroform:Isoamyl alcohol steps, applied to lung tissue samples from autopsied individuals. The resulting total DNA yield and quality, bacterial and fungal DNA amount and the microbial community structure were analyzed by qPCR and Illumina sequencing of bacterial 16S rRNA and fungal ITS genes. Bioinformatic modeling revealed that a large part of microbiome from lung tissue is composed of microbial contaminants, although our controls clustered separately from biological samples. After removal of contaminant sequences, the effects of extraction protocols on the microbiota were assessed. The major differences among samples could be attributed to inter-individual variations rather than DNA extraction protocols. However, inclusion of the bead-beater and Phenol:Chloroform:Isoamyl alcohol steps resulted in changes in the relative abundance of some bacterial/fungal taxa. Furthermore, inclusion of a pre-treatment step increased microbial DNA concentration but not diversity and it may contribute to eliminate DNA fragments from dead microorganisms in lung tissue samples, making the microbial profile closer to the actual one.

| S-EPMC7562954 | biostudies-literature

Characterization of a Stemness-Optimized Purification Method for Human Dental-Pulp Stem Cells: An Approach to Standardization.

Project description:Human dental pulp stem cells (hDPSCs) are promising for oral/craniofacial regeneration, but their purification and characterization is not yet standardized. hDPSCs from three donors were purified by magnetic activated cell sorting (MACS)-assisted STRO-1-positive cell enrichment (+), colony derivation (c), or a combination of both (c/+). Immunophenotype, clonogenicity, stemness marker expression, senescence, and proliferation were analyzed. Multilineage differentiation was assessed by qPCR, immunohistochemistry, and extracellular matrix mineralization. To confirm the credibility of the results, repeated measures analysis and post hoc p-value adjustment were applied. All hDPSC fractions expressed STRO-1 and were similar for several surface markers, while their clonogenicity and expression of CD10/44/105/146, and 166 varied with the purification method. (+) cells proliferated significantly faster than (c/+), while (c) showed the highest increase in metabolic activity. Colony formation was most efficient in (+) cells, which also exhibited the lowest cellular senescence. All hDPSCs produced mineralized extracellular matrix. Regarding osteogenic induction, (c/+) revealed a significant increase in mRNA expression of COL5A1 and COL6A1, while osteogenic marker genes were detected at varying levels. (c/+) were the only population missing BDNF gene transcription increase during neurogenic induction. All hDPSCs were able to differentiate into chondrocytes. In summary, the three hDPSCs populations showed differences in phenotype, stemness, proliferation, and differentiation capacity. The data suggest that STRO-1-positive cell enrichment is the optimal choice for hDPSCs purification to maintain hDPSCs stemness. Furthermore, an (immuno) phenotypic characterization is the minimum requirement for quality control in hDPSCs studies.

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N,N'-Bis[(E)-2,4,6-trimethyl-benzyl-idene]ethane-1,2-diamine.

Project description:The title compound, C(22)H(28)N(2), which is a double imine derived from ethane-1,2-diamine and mesityl aldehyde, has crystallographic inversion symmetry, with both C=N bonds E configured. The dihedral angle between the mesityl ring system and the imide functional group is 23.89?(17)°.

| S-EPMC3213609 | biostudies-literature

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