Anton Rieker

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Several non-natural phenolic amino acids have been synthesized.t-Butylated tyrosine and thyroxine derivatives, on one-electron oxidation, give persistent radicals which can be used as positional and/or spin labels for amino acids. Two-electron oxidation ofN-protected tyrosines leads to spirolactones, useful active esters for peptide coupling.
Three novel series of 2,6-di-tert-butyl-1,4-benzoquinone derivatives were synthesized: 4-[(3,4-disubstituted-2,3-dihydrothiazol-2-ylidene) hydrazono]-2,6-di-tert-butyl-2,5-cyclohexadien-1-ones, 4-[(3-substituted-5-carbethoxy-4-methyl-2,3-dihydrothiazol-2- ylidene)hydrazono]-2,6-di-tert-butyl-2,5-cyclohexadien-1-one s, and(More)
  • Wolfgang Hillera, Manfredo H örner, Anton Rieker, Edgar Streichh
  • 2012
IR. U V and NMR data reveal that the dichlorination product of 3,5-di-/m -butylphenol is the keto tautomer ( la ) of 3,5-di-/m -butyl-2,4-di-chlorophenol (3) instead of the ortho-quinol dichloride (2a), as assumed by Hewitt et al. (1972). According to the crystal structure determina­ tion, the first one of a monocyclic keto tautomer, l a crystallizes in the(More)
Oxygenation Catalyst, Cobalt Schiff-Base Complex, Crystal Structure, Electrochemistry N,N'-Bis(salicylidene)ethylenediaminatocobalt(III) hydroxide is treated with chloroform in methanol to yield the corresponding chloride in pure, crystalline form. Results of the crystal structure determination compare well with those in earlier reports of dimeric(More)
Z. Naturforsch. 51 b, 381-387 (1996); received August 11, 1995 Crystal Structure, Quinol, 1,4-Addition, Lithium Organyl, Cyclohex-2-en-l-ones Addition of lithium organyls to sterically hindered para-quinols leads to 1,2or 1,4-adducts. The 1,4-addition prevails, if the 4-substituents in the quinol and the organic group in the lithium organyl are large. Four(More)
Several methods have been reported for the syn­ thesis of isocyanates, most of them involving the use of phosgene: e.g. phosgene and primary amines [1] either in basic [2] or in acidic medium [1]; phosgene and diaryl urea [1]; phosgene and l-alkyl-3-arylsulphonyl urea [3]; or phosgene and sulfinyl amines [4], Isocyanates were further synthesized from(More)
Bivalent oxidation of 3,5-di-terr-butyl-hydroquinone m onoesters leads to phenoxenium ions, which can transfer an acyl group to nucleophiles. B ased on this principle, dipeptides, glyco-am ino acids and Af-sulfonyl-amino acids were synthesized from hydroquinone esters of am ino acids and p-toluenesu lfon ic acid. For this reaction, direct anodic and(More)