The total synthesis of the natural compound (8S*,14S*)‐8‐(4′‐hydroxybenzyl)‐2,3‐dimethoxyberbin‐10‐ol and its C‐8 epimer has been conveniently developed by making use of the diastereoselective Stevens rearrangement of the corresponding N‐(arylmethyl)berbinium salts as the key step.
The Polonovski–Potier reaction of trans and cis berbines N-oxides was studied. The 8-cyano derivative obtained from transN-oxides were used to synthesize 8-hydroxymethyl and 8-methyl berbines. This procedure was applied to the stereocontroled synthesis of (8R, 14S)-(−)-8-methylcanadine from (14...
From Berberis ilicifolia, a new dimer is described, but this alkaloid is related to a bisberbine. It is the first dimer of this type in Berberis.
Intramolecular amidoalkylation of nonactivated 3-(2-arylethyl)-4-hydroxyoxazolidin-2-ones in polyphosphoric acid gave oxazolo[4,3-a]isoquinolin-3-one whose hydrolysis affords isoquinoline β-amino alcohols, calycotomine analogs. Using the developed procedure, 13,13,13a-trimethylberbine was synth...
We developed direct aerobic photooxidation of 1,3-diketones to corresponding carboxylic acids in the presence of a catalytic amount of 2-chloroanthraquinone under visible light irradiation from fluorescent lamps.
In this Letter, we report the aerobic photo-oxidative synthesis of diacylamines from benzylamides in the presence of molecular oxygen and catalytic amounts of 2-chloroanthraquinones under visible light irradiation from a fluorescent lamp.
Snakes have intrathoracic stomachs and rachischisis-like spinal vertebrae. These anomalies are rare in babies and have not been previously described in combination in the English medical literature. Here we present 2 cases of total intrathoracic stomach with a foreshortened esophagus, cervical s...
Gas and water management is the key to achieving good performance from a polymer electrolyte membrane fuel cell (PEMFC) stack. Imbalance between production and evaporation rates can result in either flooding of the electrodes or membrane dehydration, both of which severely limit fuel cell perfor...
Delay-line electrodes can simplify the readout hardware and reduce the power requirements of a nuclear radiation detector by replacing dozens or hundreds of readout circuits with only one or two time-sensitive readouts per detector face. The simplified means of lateral position-sensing with micr...
We report an extremely rare and challenging combination of congenital anomalies. Only five similar cases have been described in the English language medical literature to date.A male infant was born at 30+5 weeks gestation by emergency caesarian section. Cervical spine rachischisis, shortened oe...
The present study aims to propose innovative louver-type turbulators to enhance the heat transfer rate in three major ways, i.e. core flow disturbance, jet impingement, and extended heat transfer surface. These louvers are installed in the twin-pass square channel with a hydraulic diameter (DH) ...
Community assembly theory predicts that resource availability, biotic interactions, and dispersal dynamics will determine community composition. Recent work has demonstrated that manipulating these processes or “filters” to exclude exotic species may assist in restoring invaded plant communiti...
The development of hybrid sterility is an important step in the process of speciation, however the role of adaptive evolution in triggering these postzygotic barriers is poorly understood. We show that, in the California endemic plant Collinsia sparsiflora, ecotypic adaptation to two distinct so...
The synthesis and chromatographic evaluation of a series of new Cinchona derived chiral weak anion exchangers is presented. Huisgen Cu(I) mediated alkyne–azide cycloaddition, so-called click chemistry, was used as an immobilization strategy. In this way it was possible to immobilize about 90% o...
A novel anion‐exchange organic polymer monolithic column based on monomers N‐benzylquininium chloride and acrylamide were firstly prepared by in situ copolymerization for capillary electrochromatography. Moreover, N‐benzylquininium was firstly introduced as a strong anion‐exchange functional...
Novel chiral stationary phases (CSPs) based on zwitterionic Cinchona alkaloid-type low-molecular mass chiral selectors (SOs), as they have been reported recently, were investigated in HPLC towards effects on their chromatographic behavior by mobile phase composition. Mobile phase characteristics...
The concept of recently introduced Cinchona alkaloid-type zwitterionic chiral stationary phases (CSPs) is based on fusing key cation- and anion-exchange (CX, AX) moieties in one single low-molecular mass chiral selector (SO) with the resulting CSPs allowing enantiomer separations of a wide range...
A heterogeneous, silica‐based catalyst containing 9‐amino‐9‐deoxy‐epi‐quinine (or quinidine) and a derivative of benzoic acid was synthesized through radical thiol‐ene click reaction. The acid component allows the in situ activation of cinchona amino group, acting as a bifunctional cataly...
The stereoselective complexation of tert‐butylcarbamoyl quinine and tert‐butylcarbamoyl quinidine selectors (SOs) with 3,5‐dinitrobenzoyl (DNB) derivatives of D‐ and L‐alpha amino acids (DNB‐Ala, DNB‐Val, DNB‐Leu, and DNB‐Ile) as well as achiral DNB‐Gly has been studied by vibrational ...
Two new optically active bidentate N,N‐ligands, DMIQCI (3a) and DMIQCD (3b), containing a quinuclidine core and an imidazolidin‐2‐imine unit, were synthesized. The reaction of these ligands with [(η5‐C5Me5)RuCl]4 afforded the brick‐red ruthenium(II) complexes [(η5‐C5Me5)Ru(DMIQCI)Cl] (4)...
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