83 research outputs found
A new ligand alpha-amino acid: (S)-2-amino-3-[1-(1,4,7-triazacyclononane)]propanoic acid
No full textBreakthrough in the alfa-perchlorination of acyl chlorides
No full textThe preparation of -perchloroacyl chlorides, from reaction of the corresponding unfunctionalized acyl halides with chlorine, was efficiently achieved under base-catalysis, using a tetraalkylammonium chloride as catalyst. The process is solvent-free and the procedure is easy, inexpensive, and suitable for scale-up
CuCl-catalyzed radical cyclisation of N-a-pechloroacyl-ketene-N,S-acetals: a new way to prepare disubstituted maleic anhydrides
No full textThe discovery that cycloalkanes can form thermomorphic systems with typical polar organic solvents has
led to the development of less-polar electrolyte solutions. Their mixing and separation can be regulated
reversibly at a moderate temperature range. The phase switching temperature can be controlled by
changing the solvent compositions. While biphasic conditions are maintained below the phase switching
temperature, conductive monophasic conditions as less-polar electrolyte solutions are obtained above
the phase switching temperature. After the electrochemical transformations, biphasic conditions are
reconstructed below the phase switching temperature, facilitating the separation of cycloalkane where
hydrophobic products or designed hydrophobic platforms are selectively partitioned. Several polar organic
solvents, including acetonitrile, methanol, and pyridine, can be used in this system according to the
requirement of the reactions
A Novel Short Approach to (Z)-Pulchellalactam Through TMC-ATRC of 1-Isopropyl-2-propenyl Dichloroacetate
No full textAluminum Fluorescence Detection with FRET Amplified Chemosensor
No full textA selective Al3+ fluorescence chemosensor able to detect concentrations of metal ion in the nanomolar range has been realized. The remarkable sensitivity is the result of the FRET amplification of the fluorescence emission of the ligand subunit
Chiral Pincer Ru and Os Complexes for the Fast and Efficient Hydrogen Transfer Reduction of Ketones
No full textA series of chiral HCNN ligands ((S)-1b−g) (S)-2-(1-aminoethyl)-6-(aryl)pyridine (aryl = 4-MeO-phenyl, 1b; 4-CF3-phenyl, 1c; 3,5-di-Me-phenyl, 1d; 3,5-di-CF3-phenyl, 1e; 1-naphthyl, 1f; 2-naphthyl, 1g) were synthesized starting from commercial 2-acetyl-6-bromopyridine (2), by a chemoenzymatic method involving the dynamic kinetic resolution of the corresponding secondary alcohol (rac-3). The conversion of the resulting (R)-3, obtained in 98% ee, into the homochiral amine ((S)-6), followed by Suzuki coupling with the appropriate arylboronic acids 7b−g, gave access to (S)-1b−g, isolated in 97% ee, with an overall yield up to 50%. The in situ generated pincer complexes [MCl(CNN)(PP)] (M = Ru, Os; PP = Josiphos diphosphine), prepared from [MCl2(PPh3)3], (R,S)-Josiphos diphosphines, and the ligands (S)-1b−g, were found to efficiently catalyze the asymmetric transfer hydrogenation of acetophenone in 2-propanol at 60 °C and in the presence of NaOiPr. On the basis of these data, the 2-naphthyl ruthenium and osmium derivatives [RuCl(CNN)((R,S)-Josiphos*)] (8) (HCNN = (S)-1g) and [OsCl(CNN)(PP)] (PP = (R,S)-Josiphos, 9, and (R,S)-Josiphos*, 10) were isolated from [MCl2(PPh3)3], (R,S)-Josiphos diphosphines, and the ligand (S)-1g. Complexes 8 and 10, displaying the correctly matched chiral PP and CNN− ligands, are highly active and productive catalysts for the transfer hydrogenation of alkyl aryl ketones and methyl pyridyl ketones with TOF = 105−106 h−1, using 0.005 mol % of catalysts and achieving up to 99% ee. The comparison of the catalytic activity of these pincer complexes shows that Ru and Os derivatives display similar rate and enantioselectivity
Breakthrough in the α-Perchlorination of Acyl Chlorides
No full textThe preparation of alpha-perchloroacyl chlorides, from reaction of the corresponding unfunctionalized acyl halides with Cl2, was efficiently achieved under base-catalysis using tetraalkylammonium chloride as a catalyst. The process is solvent-free and the procedure is easy, cheap and suitable for scale-up
A green way to g-lactams through a copper catalyzed ARGET-ATRC in ethanol and in the presence of ascorbic acid
No full textA ‘green’ ARGET-ATRC, for the CuCl[PMDETA] catalysed cyclo-isomerization of N-allyl-a-polychloroamides to g-lactams is described. The process works efficiently (yields 78e96%), uses a bio-solvent, as ethanol, and exploits the reducing feature of ascorbic acid to limit, at a low level (2e4%), the amount of catalyst. To preserve the efficacy of the catalytic cycle, addition of Na2CO3 is essential, which quenches the HCl released during the CuCl[PMDETA] regeneration step. Profitable features of the process are: mild reaction tem-peratures (25e37 C), relatively short reaction times (usually 5 h) and low solvent volumes (2 mmol of substrate/mL of ethanol). The method, upon stoichiometric adjustment, was also used for the synthesis of a,b-unsaturated-g-lactams from N-(2-chloroallyl)-a-polychloroamides, via a tandem process involving an ATRC and a reductive [1,2]-elimination
Highly Diastereoselective Synthesis of Cyclic Nitronic Esters from 1-(4-Morpholinyl)-1-phenylpropene with Nitroolefins
No full textOptically active alpha-phenylethylamine as efficient organocatalyst in the solvent-free reactions between 2,3-butanedione and conjugated nitroolefins
No full text(R)-(+) and (S)-()-1-phenylethylamine have been shown to promote highly diastereoselective
and complementary enantioselective formal [3 + 2]carbocyclization reactions between 2,
3-butanedione and conjugated nitroalkenes with formation of enantiomerically rich 2-hydroxy-3-
nitrocyclopentanone derivatives. The reactions were carried out both in solvent and under solventfree
conditions. The absolute configurations of the products were assigned by X-ray and circular dichroism
spectra analyse
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