No abstract

With the carbenoidal Simmons-Smith reagent (MCHgZnI), several diaryl disulfides underwent insertion of CH2 between the sulfur atoms to give bis(arylthio)methanes in yields up to 85% by NMR and 33% by isolation. Insertion of more than one CH2 sometimes occurred. An alkyl and an aralkyl disulfide were recovered unchanged. This reaction proceeds reasonably well only with aryl disulfides lacking substituents that are ortho, strongly elec Iron-withdrawing, or strongly basic in the Lewis sense. Carbenoids obtained from copper-catalyzed decomposition of diazo esters also gave insertion products. However, reactions were preferred that led to the same outcome through BF.i-catalyzed decomposition of the diazo esters; pure acids were isolated in 11-16% yield. Dichlorocarbene did not react with diaryl disulfides. With an ylide, triphenylphosphonium methylide, only trace insertion of CH2 occurred with diphenyl disulfide. The major product was tris(phenylthio)methane (64% isolated); methyl phenyl sulfide, triphenylphosphine sulfide, and thiophenol also were isolated, and a course of reaction is suggested. Di-n-propyl disulfide evidently reacted similarly. Attempted insertion of R'N moieties by reaction of nitrenes with diphenyl disulfide was unpromising.

A series of molecules of the type GXAsMe2 have been synthesized in which X is S or Se and G is a moiety such as an amino acid, a di- or tripeptide, or a lipid. The compounds have been characterized by NMR, mass spectroscopy, and elemental analysis. Cysteine was found to react directly with dimethylarsinic acid to yield cystine and S-dimethylarsinocysteine (1). This reaction occurs also with other biomolecules containing thiol groups and raises serious questions concerning the use of cacodylate buffers in the study of enzyme kinetics and in sample preparation for electron microscopy. In the presence of dimethylchloroarsine and diethylamine, homocysteine thiolactone reacts to form both the dipeptide and the S-AsMe2 bond. Results of carcinostatic, bacteriostatic, and fungicidal testing of these compounds are reported. A hypothesis is advanced to explain the observed carcinostatic action of the dimethylarsino group.

No abstract

Die Mercaptoaminosäure (I) reagiert mit (II) zum Arsenderivat (III).