β-环糊精流动相添加剂在手性分离中的应用综述

介绍了β-环糊精的基本性质,综述了β-环糊精及其衍生物作为流动相添加剂在高效液相色谱和高效毛细管电泳手性分离中的应用,并探讨了其作为手性流动相添加剂的特点.指出β-环糊精是良好的手性识别体,不仅可作为色谱手性固定相,还可作为流动相添加剂,用于手性对映体的拆分.     

Detection and quantification of plasma amyloid-β by selected reaction monitoring mass spectrometry

Amyloid-β (Aβ) in human plasma was detected and quantified by an antibody-free method, selected reaction monitoring mass spectrometry (SRM-MS) in the current study. Due to its low abundance, SRM-based quantification in 10 μL plasma was a challenge. Prior to SRM analysis, human plasma proteins as a whole were digested by trypsin and high pH reversed-phase liquid chromatography (RPLC) was used to fractionate the tryptic digests and to collect peptides, Aβ_1–5, Aβ_6–16, Aβ_17–28 and Aβ_29–40(42) of either Aβ_1–40 or Aβ_1–42. Among those peptides, Aβ_17–28 was selected as a surrogate to measure the total Aβ level. Human plasma samples obtained from triplicate sample preparations were analyzed, obtaining 4.20 ng mL⁻¹ with a CV of 25.3%. Triplicate measurements for each sample preparation showed CV of <5%. Limit of quantification was obtained as 132 pM, which corresponded to 570 pg mL⁻¹ of Aβ_1–40. Until now, most quantitative measurements of Aβ in plasma or cerebrospinal fluid have required antibody-based immunoassays. Since quantification of Aβ by immunoassays is highly dependent on the extent of epitope exposure due to aggregation or plasma protein binding, it is difficult to accurately measure the actual concentration of Aβ in plasma. Our diagnostic method based on SRM using a surrogate peptide of Aβ is promising in that actual amounts of total Aβ can be measured regardless of the conformational status of the biomarker.     

Mild,Selective Oxidation of Aromatic Alcohols Using β-Cyclodextrin-Functionalized Glass Microparticles: Characterization,Stability, and Application

The surface of glass microparticle (GMP) was functionalized with β-cyclodextrin (→ GMP-β-CD) and was characterized by x-ray photoelectron spectroscopy (XPS). GMP-β-CD was used to catalyze oxidation of alcohols into aldehydes and katones with excellent yield (86–92%). The modified surface of GMP-β-CD showed no change or degradation after repeated use as confirmed from XPS analysis after 10 cycles.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Trifluoroacetic Acid–Catalyzed Synthesis of N-(1-(3-Chlorophenyl)-3-aryl-3-oxopropyl)-2-(4-nitrophenyl)acetamides via Dakin–West Reaction

A series of novel N-(1-(3-chlorophenyl)-3-aryl-3-oxopropyl)-2-(4-nitrophenyl) acetamides were synthesized using p-nitrophenylacetonitrile, m-chlorobenzaldehyde, and aryl methyl ketones as starting materials and trifluoroacetic acid (TFA) as catalyst. This realized an improved Dakin–West reaction in which p-nitrophenylacetonitrile was involved. The chemical structures of up to 15 target molecules were characterized by ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry. This method provides a facile synthetic protocol under more moderate reaction conditions, smaller dosage (0.40 mol%) and hence lower cost of catalyst, and simpler posttreatment in comparison to other known methods. A reaction mechanism is proposed in which hydroxyacetophenone is first catalytically converted into the corresponding acetoxyacetophenone prior to be involved in the subsequent Dakin–West reaction that eventually leads to hydroxyl-acetylated target compounds.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Concise Total Synthesis of (−)-Erinapyrone B from D-(+)-Malic Acid

A convenient and facile enantioselective synthesis of (?)-erinapyrone B from commercially available D-(+)-malic acid has been achieved in seven steps. One of the key steps in this synthesis was the one-pot reaction of palladium(II)-mediated Wacker-type oxidative cyclization in the presence of a catalytic amount of p-toluenesulphonic acid (p-TsOH) which has been found to be effective for the preparation of enantiopure 2,3-dihydro-4H-pyran-4-one from the corresponding enantiopure β-hydroxyenone via enantio-enriched diketohydroxy intermediate.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Triphenylphosphine-Catalyzed,Novel, One-Pot,Multicomponent Synthesis of Functionalized β-Acetamido Carbonyls

An efficient triphenylphosphine-catalyzed synthesis of β-acetamido carbonyls via multicomponent reaction of aromatic aldehydes, enolizable ketones or β-keto esters, acid chlorides and acetonitrile at room temperature is described. The process is remarkably simple, environmentally benign, and uses Lewis base for the first time in such type of reaction.     

One-Pot Synthesis of Mannich Bases Under Solvent-Free Conditions

A mild and practically convenient one-pot procedure for the Mannich reaction via condensation of amines, aldehydes and malonates, β-ketoesters, or β-dicarbonyl compounds has been carried out without using any organic solvent, metallic catalyst, or Lewis acids or bases at room temperature. The present protocol offers several advantages, such as goods yields, simple procedure with easy workup, and the absence of any volatile, hazardous organic solvents and metallic catalyst.     

Heteroatom effect on potential energy topology. A novel reaction mechanism of stereospecific Staudinger synthesis

The Staudinger synthesis of various β-carbolines and thienopyridines with acetyl chloride derivatives led to novel β-lactam-type fused heterocyclic compounds. The reaction was stereospecific, giving exclusively the cis cycloadducts as racemates. The enthalpy profile and the driving force for the cis-selectivity of this cycloaddition was studied by high level quantum chemical calculations and was assigned to a new effect of the neighbouring heteroatom of the acyl group. In the course of the reaction a new side product was formed supporting the mechanistic results.     

Regioselective dehydrative intramolecular heteroannulation of β-allyl-β-hydroxy dithioesters: facile and straightforward entry to 2H-thiopyrans

β-Allyl-β-hydroxy dithioesters have been employed in the synthesis of hitherto unreported and synthetically demanding 2H-thiopyrans via regioselective intramolecular annulation strategy. Lewis acid BF₃·Et₂O efficiently mediates the regioselective dehydration followed by intramolecular thioannulation at room temperature. The attractive features of this protocol include mild conditions, high atom-economy and excellent yields with the elimination of water as the only by-product.