Thiols allene derivatives

General Reaction Chemistry of Sulfonic Acids. Sulfonic acids may be used to produce sulfonic acid esters, which are derived from epoxides, olefins, alkynes, allenes, and ketenes, as shown in Figure 1 (10). Sulfonic acids may be converted to sulfonamides via reaction with an amine in the presence of phosphorus oxychloride [10025-87-3], POCl3 (11). Because sulfonic acids are generally not converted direcdy to sulfonamides, the reaction most likely involves a sulfonyl chloride intermediate. Phosphorus pentachloride [10026-13-8] and phosphorus pentabromide [7789-69-7] can be used to convert sulfonic acids to the corresponding sulfonyl halides (12,13). The conversion may also be accomplished by continuous electrolysis of thiols or disulfides in the presence of aqueous HQ [7647-01-0] (14) or by direct sulfonation with chlorosulfuric acid. Sulfonyl fluorides are typically prepared by direct sulfonation with fluorosulfuric acid [7789-21-1], or by reaction of the sulfonic acid or sulfonate with fluorosulfuric acid. Halogenation of sulfonic acids, which avoids production of a sulfonyl halide, can be achieved under oxidative halogenation conditions (15). 

Ketenes easily add water,alcohols, amines and thiols to give derivatives of phosphorylated carboxylic acids ( -7). Phosphorylated ketenes undergo reactions of cyclo"aadition to vinyl ethers,diazomethane,styrene, cyclopentadiene, etc. From phosphorylated ketenes other phosphorylated cumulenes can be obtained,for example allenes,isocyanates,ketenimines... 

In the case of thiols (RSH), the corresponding hydrothiocarbonylation takes place successfully at the terminal double bond, as shown in Scheme 11.8 [11]. A possible pathway is as follows (1) formation of an H-Pd-SR species via oxidative addition of H -S R to Pd(0) (2) coordination of the allene double bond and subsequent insertion into a Pd-H bond to form an allypalladium complex intermediate (3) CO insertion resulting in the formation of an acylapalladium carbonyl species and (4) reductive elimination affording the thioester derivates. 

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