Thiols reaction with acyl halides

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. 

Seleno-carboxylic acid esters (selenol esters) 2 are also prepared like thiol esters by the reaction of acyl halides with selenols, or diselenides as well as their alkali metal salts. Most of the preparative methods for thiol esters shown in Sect. 2.1 are applicable to the synthesis of selenol esters 2. Unique synthetic... 

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). 

The open-chained thioacetamide, on the other hand, yields iminium salts (34) on acylation. Reaction of (34) with alkyl halides and subsequent hydrolysis results in the formation of thiocarboxylic esters (1). This reaction is actually performed in one step under phase transfer catalysis (equation 21). No unpleasant smelling thiols or thiocarboxylic acids are required as educts, the yields are high and a large variety of substituents R and R are possible. ... 

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. 

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