Gyula Parlagh

Synthesis and alkali cation extraction ability of 1,3-alt-thiacalix[4]mono(crown) ethers

Abstract The first representatives of 1,3-alt-thiacalix[4]mono(crown-5 and -6) ethers were synthesized by the cyclocondensation of 25,27-dialkoxythiacalix[4]arenes with tetraethylene glycol ditosylate and 1,14-diiodo-3,6,9,12-tetraoxatetradecane, respectively. The complexing abilities of ligands were determined by the alkali (Li+, Na+, K+, Rb+, Cs+) picrate extraction method.

Enantioselective Michael addition of 2-nitropropane to chalcone analogues catalyzed by chiral azacrown ethers based on α-d-glucose and d-mannitol

Abstract The chiral monoaza-15-crown-5 type lariat ethers 1 and 2 derived from α- d -glucose and from d -mannitol, respectively, have been applied as phase transfer catalysts in the enantioselective Michael addition of 2-nitropropane to aromatic 3b–c and heteroaromatic 3d–h chalcone analogues. Among the catalysts, the glucose-based 1c with a phosphinoxidobutyl side arm proved to be the most effective, it inducing 34% e.e. for 4b, 59% e.e. for 4c, 80% e.e. for 4d, 64% e.e. for 4e, 17% e.e. for 4f. Catalyst 1a having 3-hydroxypropyl substituent resulted in 81% e.e. for compound 4g. The formation of the (+)-(S)-enantiomer of 4 was preferred using crown ethers 1a–c, while the (−)-(R)-enantiomer was in excess with catalyst 2. The absolute configuration of the Michael adduct 4d was determined by single-crystal X-ray analysis.

A facile synthesis of 4- and 6-chloromethyl-1H-indole-2-carboxylates: replacement of a sulfonic acid functionality by chlorine

Valuable new synthetic intermediates, 4- or 6-chloromethyl-1H-indole-2-carboxylates, were prepared by the elimination of SO2 from 2-ethoxycarbonyl-1H-indole-4- or 6-methanesulfonic acids, respectively, which are easily accessible by Fischer-type indolization.

Site-selective phosphorylation of arylphospholes through reaction with phosphorus tribromide

The reaction of 1-(tri-tert-butylphenyl)phosphole (1) with phosphorus tribromide gave the 3-dibromophosphino intermediate (2) selectively that was useful in the synthesis of phosphonic amides 4, H-phosphinic amide 6 and H-phosphinates 8. A similar transformation of the 1-(triisopropylphenyl)phosphole (9) led to a 2-substitution furnishing phosphonic amides 12 or H-phosphinates 14. The phosphorylated phospholes (4, 6, 8) were tested as ligands of transition metal complexes in hydroformylation.

Formation of aryl dialkylphosphinates from dialkylphosphinous chlorides and arylmagnesium bromides under oxidative conditions

The reaction of dialkylphosphinous chlorides (1) with arylmagnesium bromides carried out in the air atmosphere was found to afford aryl-dialkylphosphine oxides (2) and aryl dialkylphosphinates (3) in a comparable quantity. Formation of the latter product (3) is the first example that an aryl-dialkylphosphine, formed as an intermediate, is autooxidized to the corresponding phosphinate.