Hubert Gstach

Identification and X-ray co-crystal structure of a small-molecule activator of LFA-1-ICAM-1 binding.

Stabilization of protein–protein interactions by small molecules is a concept with few examples reported to date. Herein we describe the identification and X-ray co-crystal structure determination of IBE-667, an ICAM-1 binding enhancer for LFA-1. IBE-667 was designed based on the SAR information obtained from an on-bead screen of tagged one-bead one-compound combinatorial libraries by confocal nanoscanning and bead picking (CONA). Cellular assays demonstrate the activity of IBE-667 in promoting the binding of LFA-1 on activated immune cells to ICAM-1.

Geminale Azo- und Heteroelement-Funktionen, IV: O- und N-Funktionelle Arylazo-diphenylmethyl-Derivate

The reaction of benzophenone arylhydrazones1 with bromine in pyridine solution yields 1-(arylazo-diphenylmethyl)-pyridinium bromides2 and pyridine · HBr. The inseparable salt mixtures upon treatment with a series of O- and N-nucleophiles undergo displacement of the pyridinium moiety of2 affording the title compounds3–14.

Triazolium salts. II, Derivatives of 4,5-dihydro-5,5-dimethyl-1,2,4-triazol-3-one

The title compound 1a was converted into novel N-4-substituted derivatives. Catalytic hydrogenation of 1a yielded the cyclotautomer of acetone semicarbazone 4. Meerwein salts alkylated the diazene function of 1a at N-2 affording the triazolium salts 5

Triazolium salts. III, 1-(1,1-dimethylethyl)4,5-dihydro-3,3-dimethyl-5-oxo-3H-1,2,4-triazolium chloride

The cycloaddition reaction of acetone t-butylhydrazone (6) with cyanic acid yielded the 1,2,4-triazolidin-3-one 1c, subsequent oxidative ring-opening afforded the t-butylazoalkyl isocyanate 3c. Derivatization of the isocyanate function of 3c furnished the carbamic acid derivatives 7-10. Reactions involving both geminal functional groups of 3c led to the heterocycles 11, 12, and the title compound 4c; some properties and reactions of the triazolium salt 4c are described