Dennis Fiorini

Conjugate addition of nitroalkanes to N-substituted maleimides. Synthesis of 3-alkylsuccinimides and pyrrolidines

Abstract 3-Alkylidenesuccinimides obtained by conjugate addition of nitroalkanes to N -substituted maleimides can be reduced to the corresponding 3-alkyl derivatives by catalytic hydrogenation. 3-Alkylsuccinimides can be further reduced using BH 3 ·Me 2 S complex to afford 3-alkylpyrrolidines in good yield.

TBD-catalysed solventless synthesis of symmetrically N,N′-substituted ureas from primary amines and diethyl carbonate

Symmetrically N,N′-substituted ureas were obtained from primary amines in very good yields under solvent-less conditions using diethyl carbonate (DEC) as the carbonylation reagent and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the base catalyst. The products are precipitated directly from the reaction mixture after a volatile organic compound (VOC) free aqueous work-up. The catalyst can be recovered and reused.

Unprecedented, Selective Nef Reaction of Secondary Nitroalkanes Promoted by DBU Under Basic Homogeneous Conditions

Secondary nitrocompounds can be converted into the corresponding ketones under basic conditions using DBU in acetonitrile. Primary nitroalkanes are unaffected by these conditions.

Activated aluminum oxide selectively retaining long chain n-alkanes: Part II. Integration into an on-line high performance liquid chromatography-liquid chromatography-gas chromatography-flame ionization detection method to remove plant paraffins for the determination of mineral paraffins in foods and environmental samples.

Aluminum oxide activated by heating to 300-400 degrees C retains n-alkanes with more than about 20 carbon atoms, whereas iso-alkanes largely pass non-retained (with characteristics described in more detail in Part I). This property is useful for the analysis of mineral oil contamination of foods and other matrices: it enables the removal of plant n-alkanes, typically ranging from C(23) to C(33), when they disturb the analysis of mineral paraffins (usually almost exclusively consisting of iso-alkanes). An on-line HPLC-LC-GC-FID method is proposed in which a first silica gel HPLC column isolates the paraffins from the bulk of edible oils or extracts and is backflushed with dichloromethane. In a second separation step, a 10 cm x 2 mm i.d. column packed with activated aluminum oxide separates the long chain n-alkanes from the fraction of the iso-alkanes which is transferred to GC-FID by the on-column interface and the retention gap technique. The retained n-alkanes are removed by flushing with iso-octane.

MCM-41-TBD as a new, efficient, supported heterogeneous catalyst for the synthesis of thioureas

The preparation of thioureas, by reaction of carbon disulfide with primary amines, can be efficiently catalyzed, under heterogeneous conditions, by MCM-TBD as a new and reusable catalyst.

Contamination of Grape Seed Oil with Mineral Oil Paraffins

The contamination of 11 commercial grape seed oils with paraffins of mineral oil origin was analyzed by online-coupled HPLC-HPLC-GC-FID and ranged from 43 to 247 mg kg(-1). The analysis of the marc and seeds indicated that the contamination is primarily from the peels. Since superficial extraction of the seeds with hexane removed most of the mineral paraffins, the contamination of the seeds is largely on the surface, perhaps transferred from the peels during storage of the marc. Mechanical purification of the seeds combined with washing with hexane reduced the contamination of the oil by a factor of about 10. The refining process removed 30% of the mineral paraffins, primarily the more volatile components. Oil obtained from the seeds of fresh grapes, including grapes not having undergone any phytochemical treatment, contained clearly less mineral paraffins (up to 14 mg kg(-1)), and the peels were less contaminated, suggesting an environmental background contamination. To this an additional contamination might be added by a treatment of the grapes used for wine making.

Neutral alumina catalysed synthesis of 3-nitro-1,2-dihydroquinolines and 3-nitrochromenes, under solvent-free conditions, via tandem process

It has been found that neutral alumina carries out the solvent-free reaction of 2-aminobenzaldehyde or salicylaldehyde over a range of nitroalkenes, under mild and convenient conditions, allowing the one pot synthesis of 3-nitro-1,2-dihydroquinolines and 3-nitrochromenes, respectively.

Uncatalyzed conversion of linear α-nitro ketones into amides by reaction with primary amines under solventless conditions

Abstract The reaction of linear α-nitro ketones with primary amines allows the formation of amides through the cleavage of the carbon–carbon bond between the carbonyl group and the carbon-nitro group moiety, promoted by the nucleophilic effect of the amine. The reaction is performed at room temperature, without any catalyst and/or solvent.

Activated aluminum oxide selectively retaining long chain n-alkanes. Part I, description of the retention properties

Aluminum oxide activated by heating to 350-400 degrees C retains n-alkanes with more than about 20 carbon atoms, whereas iso-alkanes largely pass the column non-retained. Retention of n-alkanes is strong with n-pentane or n-hexane as mobile phase, but weak or negligible with cyclohexane or iso-octane. It is strongly reduced with increasing column temperature. Even small amounts of polar components, such as modifiers or impurities in the mobile phase, cause the retention of n-alkanes to irreversibly collapse. Since n-alkanes are not more polar than iso-alkanes and long chain n-alkanes not more polar than those of shorter chains, retention by a mechanism based on steric properties is assumed. The sensitivity to deactivation by polar components indicates that polar components and n-alkanes are retained by the same sites. The capacity for retaining n-alkanes is low, with the effect that the retention of n-alkanes depends on the load with retained paraffins. These retention properties are useful for the pre-separation of hydrocarbons in the context of the analysis of mineral oil paraffins in foodstuffs and tissue, where plant n-alkanes, typically ranging from C(23) to C(33), may severely disturb the analysis (subject of Part II).

Microbiota modulation counteracts Alzheimer’s disease progression influencing neuronal proteolysis and gut hormones plasma levels

Gut microbiota has a proven role in regulating multiple neuro-chemical pathways through the highly interconnected gut-brain axis. Oral bacteriotherapy thus has potential in the treatment of central nervous system-related pathologies, such as Alzheimer’s disease (AD). Current AD treatments aim to prevent onset, delay progression and ameliorate symptoms. In this work, 3xTg-AD mice in the early stage of AD were treated with SLAB51 probiotic formulation, thereby affecting the composition of gut microbiota and its metabolites. This influenced plasma concentration of inflammatory cytokines and key metabolic hormones considered therapeutic targets in neurodegeneration. Treated mice showed partial restoration of two impaired neuronal proteolytic pathways (the ubiquitin proteasome system and autophagy). Their cognitive decline was decreased compared with controls, due to a reduction in brain damage and reduced accumulation of amyloid beta aggregates. Collectively, our results clearly prove that modulation of the microbiota induces positive effects on neuronal pathways that are able to slow down the progression of Alzheimer’s disease.