Diethyl phosphonates were conveniently converted into ethyl 4-aminophenyl and ethyl 4-[amino(hydroxyimino)methyl]phenyl phosphonates as potentially useful intermediates for the preparation of functionalized phenyl phosphonates.
Aliphatic linear and α-branched aldehydes efficiently undergo arylation at the α-position upon treatment with aryl bromides using an appropriate palladium catalyst system that is capable of overcoming aldol condensation of the substrates.
A comparative synthesis of the classic difficult sequence ACP(65-74) on 2% crosslinked JandaJel and 1% crosslinked polystyrene-divinylbenzene, (PS-DVB, Merrifield resin) by Boc/benzyl chemistry is presented. The JandaJel batch used was of nearly double the loading of PS-DVB, yet 12.2% less of the des-Val 65 contaminant was observed in the JandaJel synthesis. These results suggest that...
A fast alumina-promoted solid-phase Michael addition of enamines to conjugated enones is described under microwave irradiation in high yields. The 1,5-diketo Michael adducts have been converted into a novel class of 1',2'-diazepino(17,16-d') steroids.
Two calix(diseleno)crown ethers 3 and 4 were synthesized by reaction of the disodium salt of 1,3-propanediselanol with the preorganized 1,3-dibromoethoxylcalixarenes 1 and 2. Compound 3 forms an interesting infinite sheet aggregate via self-inclusion and intermolecular Se...Se interactions in the solid state. Preliminary evaluation of 3 and 4 as ionophores for ion-selective electrodes (ISEs)...
Ketyl radicals were produced from ketones by photochemical electron transfer and subsequent proton transfer from tertiary amines. These radicals were stereoselectively added to (5R)-5-(-)-menthyloxy-2[5H]-furanone 1. Due to their low reactivity, the α-aminoalkyl radicals which were generated at the same time were not added to 1. The ketones were used in stoichiometric quantities.
Substituted bicyclo[5.3.0]azulene compounds are synthesized by intermolecular [8+2] cycloaddition reactions of lactone 1 with vinyl ethers-acetal decomposition products-are described. The reactions were found to be temperature and solvent dependent.
Reaction of the 3,6-bis(tosyloxymethyl)pyridazine (1) with two equivalents of (1R-2S)-norephedrine or (1S-2R)-1-amino-2-indanol leads to the formation of C 2 -chiral dinucleating ligands containing a 3,6-disubstituted pyridazine core flanked by aminoalcohol pendant arms, namely 3,6-bis((1R-2S)-(2-hydroxy-1-methyl-2-phenyl-ethyl)aminomethyl)pyridazine (2) and 3,6-bis((1S-2R)-(2-hydroxy-indan-1-yl)aminomethyl)pyridazine...
New oligophenylenevinylene-terminated phenylenevinylene dendrons have been prepared and attached to C 60 by a 1,3-dipolar cycloaddition of the azomethine ylides generated in situ from the dendritic aldehydes and N-methylglycine. Preliminary photophysical investigations of the resulting fullerodendrimers have revealed interesting light-harvesting properties.
The hole transfer through DNA was monitored by the transient absorption of radical cation of phenothiazine (Ptz + ). The occurrence of hole transfer from G + generated in DNA to Ptz was observed in the time range of 100 μs. The hole transfer to Ptz was significantly suppressed by introducing oxG as a hole trap in DNA, and the trapping reaction of oxG + by water was suggested...
The electrochemical synthesis of p-tolylsulfonylbenzenediols (4a-c) by anodic oxidation of catechols (1a-c) in the presence of 4-toluene sulfinic acid (3) is described. Products were obtained in an undivided cell in good yields and purity. The mechanism of oxidation has been studied in aqueous solution using cyclic voltammetry and controlled-potential coulometry.
Allylic and benzylic alcohols are oxidised to the corresponding carbonyl compounds using tert-butyl hydroperoxide, preferably in stoichiometric amounts, and dirhodium(II) tetraacetate as catalyst (1 mol%) in dichloromethane at ambient temperature.
The bismuth nitrate-mediated guanidylation of N-benzoylthioureas was studied. This salt proved to be an effective guanylating reagent and allowed the obtention of N-benzoyl-guanidines in good yields. The methodology described is a promising alternative to the use of toxic HgCl 2 in the synthesis of polysubstituted guanidines.
Diazomethane ring expansion of 3 followed by deketalization, led to the formation of bicyclodione intermediates 6 and 8. These intermediates underwent internal aldol cyclization to give the tricyclic adducts 7 and 9 in a 1:1 ratio, respectively.
A new water-soluble calixarene-based bipyridyl podand was prepared by incorporation at the upper rim of four sulphonate groups; the association of its hydrophilic and chelating properties was positively evaluated in the complexation of copper(I) in water.
A diastereoselective route to an enantiopure 4,4-disubstituted cyclohex-2-en-1-ol has been developed using the synthetic equivalent of chiral 4-hydroxycyclohex-2-en-1-one. Its stereochemistry has been determined by its transformation into the Aspidosperma indole alkaloid (+)-quebrachamine.
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