A direct approach to β-keto sulfones via AgNO3/K2S2O8 catalyzed aerobic oxysulfonylation of alkenes in aqueous medium

An efficient, AgNO₃/K₂S₂O₈ catalyzed one-pot radical route to β-keto sulfones from alkenes is reported. The protocol involves oxysulfonylation of alkenes with air (O₂) and inexpensive sodium arenesulfinate salts under mild conditions. It is highly practical and allows the use of easily available starting materials in an open flask and aqueous medium at ambient temperature.     

The First Europium(III) β‐Diketonate Complex Functionalized Polyhedral Oligomeric Silsesquioxane

The first europium(III) β‐diketonate complex functionalized polyhedral oligomeric silsesquioxane (POSS) has been obtained by immobilization of such a complex at a silicon vertex of the POSS cage through the complexation of Eu³⁺ ions with thenoyltrifluoroacetone‐functionalized POSS. The new molecular hybrid material is liquid at room temperature, and shows bright‐red emission when irradiated with UV light due to energy transfer from the thenoyltrifluoroacetone ligand to the coordinated Eu³⁺ ions. Thermal analysis has revealed a significant improvement in the thermal stability of the material compared with tris(2‐thenoyltrifluoroacetonate)europium(III) dihydrate, [Eu(TTA)₃] ? 2 H₂O. In the context of recent advances in printable electronic technology, this novel luminescent organic liquid with the characteristic emission of Eu³⁺ may potentially be useful in the development of next‐generation organic devices such as flexible displays.     

Fe(HSO4)3·SiO2 as an efficient,heterogeneous and recyclable catalyst for the synthesis of bis-(β-enaminones) and bis-(β-enamino esters)

Fe(HSO₄)₃·SiO₂ is used to catalyze the condensation of β-diketones and β-keto esters with aromatic and aliphatic diamines in solvent-free conditions at room temperature. This afforded the corresponding bis-(β-enaminones) and bis-(β-enamino esters) in very good to excellent yields. Short reaction times, easy work-up procedure, and reusability of the catalyst are the merits of this study.     

Facile diastereoselective synthesis of functionally enriched hydantoins via base-promoted intramolecular amidolysis of C-3 functionalized azetidin-2-ones

Synthesis of functionally enriched hydantoins has been developed and validated via base-assisted intramolecular amidolysis of C-3 functionalized β-lactams.     

Stereoselective total synthesis of acremomannolipin A and its anomer,the potent calcium signal modulators with a novel glycolipid structure: role of the stereochemistry at the anomeric center on the activity

A full account of stereoselective total synthesis of a novel glycolipid, acremomannolipin A (1), the potent calcium signal modulator isolated from Acremonium strictum, by employing the stereoselective β-mannosylation of 4,6-O-benzylidene-protected mannosyl sulfoxide with d-mannitol as the key reaction is described. The α-anomer (epi-1) of 1 was also synthesized selectively. The calcium modulating activity was reduced upon inversion of the configuration at the anomeric center, indicating that the β-configuration of the mannose moiety is preferable for the activity.     

Dimethyl(3,3,3-trifluoropropyl)silyldiethylamine—A new silylating agent for the derivatization of β-blockers and β-agonists in environmental samples

Research into alternative derivatizing agents remains a major task in the trace analysis of polar compounds using GC. DIMETRIS (dimethyl(3,3,3-trifluoropropyl)silyldiethylamine) is a new and interesting proposition in this field. This agent possesses strong nucleophilic properties and reacts selectively with hydroxyl groups. The derivatization reaction takes place in the absence of any catalysts. The derivatives possess good chromatographic properties and are easily detected by mass spectrometry. By introducing fluorine atoms into the structure of the derivatives, we were able to use an electron-capture detector for their GC determination. No degradation of new derivatives was observed after seven days of storage in a refrigerator or during the GC analyses. Unlike a number of acylation agents, DIMETRIS does not corrode the analytical equipment. In this work β-blockers and β-agonists were used for testing the derivatizing properties of DIMETRIS. Derivatization of these drugs was optimal at 30 °C for 30 min. The method quantification limits of the target compounds determined in tap water samples by SPE-GC–MS(SIM) ranged from 3 to 40 ng L⁻¹ and resembled those obtained with samples derivatized using a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and 1% chlorotrimethylsilane (TMCS) (hitherto regarded as optimal). This work confirmed that DIMETRIS is suitable for the trace analysis of pharmaceuticals in natural samples and provides an interesting alternative to silylating and acylating agents.     

Unexpected Synthesis of Highly Substituted Indole Derivatives

An unexpected synthesis of highly substituted indole derivatives was provided by treating 2-[2-(4-fluorophenyl)-2-oxo-1-phenylethyl]-4-methyl-3-oxo-pentanoic acid phenylamide with aryl hydrazines in the presence of trifluoroacetic acid in tetrahydrofuran.     

Europium Triflate–Catalyzed One‐Pot Synthesis of 2,4,5‐Trisubstituted‐1H‐imidazoles via a Three‐component Condensation

A simple, efficient, and practical procedure for synthesis of 2,4,5‐trisubstituted‐1H‐imidazoles via the condensation of benzoin or acetoin, aromatic aldehydes, and ammonium acetate using europium triflate [Eu(OTf)₃] as a novel catalyst in high yields is described. The catalyst can be recovered conveniently and reused at least four times without any loss of activity.     

Facile Procedure for the Synthesis of 3-Acetyl-9-ethylcarbazole and Corresponding Functionalized Bis-β-diketone Compounds

Acetylation-substituted N-ethylcarbazole at the 3-position was synthesized in 80% yield using ZnCl₂ as catalyst, and its corresponding functionalized bis-β-diketone compounds 2a and 2b were prepared by Claisen condensation with acceptable yields. Lanthanide complexes with the two compounds could be used as potential luminescent materials.     

Trading N and O: asymmetric syntheses of β-hydroxy-α-amino acids via α-hydroxy-β-amino esters

Both diastereoisomers of 2-amino-3-hydroxybutanoic acid and 2-amino-3-hydroxy-3-phenylpropanoic acid have been prepared from enantiopure α-hydroxy-β-amino esters via the intermediacy of the corresponding cis- and trans-aziridines. Aminohydroxylation of two α,β-unsaturated esters produced enantiopure 2,3-anti-α-hydroxy-β-amino esters in >99:1 dr. Subsequent epimerisation at the C(2)-position via a sequential oxidation/diastereoselective reduction protocol gave the corresponding enantiopure 2,3-syn-α-hydroxy-β-amino esters in >99:1 dr. These syn- and anti-substrates were then converted into the corresponding N-Boc protected cis- and trans-aziridines, respectively, via a three step reaction sequence: (i) hydrogenolysis and in situ N-Boc protection; (ii) OH-activation; and (iii) aziridine formation. Subsequent regioselective ring-opening of the C(3)-methyl-aziridines with Cl₃CCO₂H proceeded with inversion of configuration to give the corresponding 2-amino-3-trichloroacetate esters, whereas the analogous reaction with the C(3)-phenyl-aziridines resulted in rearrangement to the corresponding oxazolidin-2-ones with retention of configuration. In each case, hydrolysis of the products from these ring-opening reactions produced the corresponding enantiopure β-hydroxy-α-amino acids as single diastereoisomers.