Sulfenyl chlorides conversions

Another -activation of amino acids for peptide synthesis is achieved by preparing sulfenamides from sulfenylimidazoles. A sulfenylimidazole is formed in situ from the sulfenyl chloride (prepared from the disulfide and chlorine) and imidazole, which reacts further with an amino acid ester to give a sulfenamide in high yield. Conversion of such sulfenamides with IV-acyl amino acids by means of triphenylphosphine affords dipeptides with racemization of less than 0.5%.[481... 

Insertion of carbon monoxide into Csp2—Zr bonds occurs readily at ambient temperatures or below to produce a,(5-unsaturated, reactive acyl zirconocene derivatives [27—29]. Early work by Schwartz demonstrated the potential of such intermediates in synthesis [5d], as they are highly susceptible to further conversions to a variety of carbonyl compounds depending upon manipulation. More recently, Huang has shown that HC1 converts 16 to an enal, that addition of a diaryl diselenide leads to selenoesters, and that exposure to a sulfenyl chloride gives thioesters (Scheme 4.11) [27,28]. All are obtained with (F)-stereochemistry, indicative of CO insertion with the expected retention of alkene geometry. 

In earlier days it was fairly common to suggest that sulfenium ions, RS+, were involved as intermediates in a number of these substitutions, particularly those in which sulfenyl halides RSX reacted with very weak nucleophiles, or those where electrophilic catalysis of the substitution was observed (Parker and Kharasch, 1959). However, it has since become evident (Owsley and Helmkamp, 1967 Helmkamp et al., 1968 Capozzi et al., 1975) that sulfenium ions are almost impossible to generate as intermediates. For example, Capozzi et al., (1975) showed that although treatment of a sulfenyl chloride RSC1 with the powerful Lewis acid antimony pentafluoride led to the complete conversion of the sulfenyl chloride to a cation, what was formed was, not the sulfenium ion RS+, but rather the cation [59] in reaction (172). These results, and others... 

H. Cyclizations, Conversions and Reactions of Sulfenyl Chlorides with Metal Carbonyls. ... 

Further reaction of the sulfenyl chlorides to the sulfides does not take place. It can also be deduced that the substitution reaction occurred with the chelate ring unruptured, since no sulfides (usually obtained with sulfur dichloride and the enol form of 2,4-pentanedione) were obtained. The structures of the sulfenyl chlorides of the metal acetylacetonates were confirmed by their infrared spectra, and by conversion of the sulfenyl chloride to a thiocyano group by reaction with cyanide ions. The tris(3-thiocyano-... 

Although very few studies of free-radical reactions of sulfenyl compounds have as yet been reported, irradiation with ultraviolet light enhances the rate of addition of CI3CSCI to olefins.218 Evidence for free-radical behavior is found in the easy decompositions which are observed for RSC1 under irradiation, e.g., the conversion of methanesulfenyl chloride to chloromethanesulfenyl chloride287 under the influence of sunlight. In the photoinitiated chlorination reaction with trichloro-... 

The sulfenyl phthalimides are one of the oldest groups of fungicides and are effective, safe and persistent (B-77MI10706). Captan (59) is cheaply made from the Diels-Alder adduct of butadiene and maleic anhydride, followed by conversion to the imide and reaction with trichloromethanesulfenyl chloride. Folpet (60) and captafol (61) are similar in structure. 

Sosnovsky, G. and J.A. Krogh. 1979. The utilization of sulfur, sulfenyl, selenenyl, and seleninyl chlorides in the conversion of aldoximes to nitriles. Z Naturforsch B 34 511-515. 

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