Acyl halides thiols

The salts of the thiol react with alkyl and acyl halides to form alkyl or acyl derivatives (Table II). For a discussion of the constitution of these compounds see Section IV, D. 

Acyl halides react with thiols, in the presence of zinc, to give the corresponding thio ester. ... 

The salts of thiatriazole-5-thiol react with alkyl and acyl halides to give S-alkyl and 5-acyl derivatives. Lieber et al. formulated the acyl derivatives as 4-substituted thiatriazolines, but it has been demonstrated unequivocally that both acylation and alkylation afford the 5-substituted products. A detailed discussion of this problem has been published elsewhere (76AHC(20)145). 

The alkyl halides (halogenoalkanes), thiols and amines are at the same oxidation level as the alcohols, while acyl halides, thioacids and amides are similarly related to the carboxylic acids. Like oxygen, sulfur can be inserted into a chain to generate the equivalent of an ether such as the thioether... 

Acyl halides react with thiols, in the presence of zinc, to give the corresponding thio-ester. " The reaction of acid chlorides or anhydrides (see 16-62) with diphenyldiselenide, in the presence of Sm/CoCl2 or Sm/CrCl3 gave the corresponding seleno ester (PhSeCOMe). 

Reaction of thiols or thiolates with acyl halides, chlorides in particular, represents the standard method for preparing thiol carboxylic esters (c/. ref. 33 and the literature cited therein). Since thiols ate strong nucleophiles, the acylation even takes place in the absence of base. However, to obtain excellent yields under mild conditions, tertiary amines are added or metal (Si, Sn, T1 Cu ) derivatives of the thiols are used. The following examples demonstrate the scope of the method. 

The thiol sulfur atom is a powerful nucleophile and can participate in nucleophilic substitution at a saturated carbon atom when this is attached to a good leaving group L (Scheme 5). An illustrative example is provided by the condensation of a thiol with an acyl halide to yield the corresponding thiolocarboxylic acid ester (Scheme 5). 

A new decarboxylative route to free radicals, which has proved particularly successful in preparative work, embodies the thermal (or photochemical) decomposition reaction of 1-hy-droxypyridine-2(l/f)-thione esters 23 with tributyltin hydride, /er/-butanethiol, or a similar hydrogen donor.These esters can be easily prepared from acyl halides and the sodium salt of l-hydroxypyridine-2(l//)-thione, or from the carboxylic acid, dicyclohexylcarbodiimide and l-hydroxypyridine-2(l/f)-thione. The intermediate radicals were readily reduced to the corresponding hydrocarbons 24 in efficient chain reactions with organotin hydrides or thiols as reaction partners, and the proportion of rearranged to unrearranged products could be controlled by the choice of hydrogen donor, its concentration and the temperature. This system was sufficiently quantitative and well behaved for use in kinetic studies, and the rate constants of the (S-scission reactions of the listed cyclopropylmethyl species were determined. 

---