Thiocyanates thiol carboxylic esters

Other methods that can be used to prepare thiol esters from carboxylic acids include the use of aryl thiocyanates,12 thiopyridyl chloroformate,13 2-fIuoro- V-methylpyridinium tosylate,14 1-hydroxybenzotriazole, 5 and boron thiolate.16 Direct conversion of 0-esters to 5-esters can also be effected via aluminum and boron reagents.17 However, the applicability of these 1217 and other more recent methods18 to the selective thiol ester formation discussed above has not been clearly defined. 

Methyl and S-aryP thiocarboxylic esters can also be prepared directly from carboxylic acids if thiocyanates or chlorothioformates are used instead of thiols (equations 11 and 12). 

Tliietane 1-oxide, 380 Thioacetalization, 165-166 Thioanisole-Chlorine. 159 a-Thiobutyrolactone, 158 7-Thiobutyrolactone, 206 Thiochromane-3-carboxylic acids, 385 Thio-Claisen rearrangement, 385 Thiocyanates, 155 Thioethers, 364 Thioglycolic acid, 366 4(5)-Thioimidazoles, 377 Thiol esters, 100 Thiomethoxymethyllithium, 379 Thiones, 175,176 Thionyl chloride, 366 Thionyl chloride-Triethylamine, 367 Thiophenol, 330, 367-368 Thiourea, 278 Titanium(O), 368-369 Titanium (III) chloride, 369 Titanium(III) chloride-Lithium aluminum hydride, 369-370 Titanium (IV) chloride, 228, 370-372... 

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