Alcohols thioacylation

The synthesis of (+)-curacin A 271 was accomplished by a selective and facile thioacylation of amino alcohol 268 with the benzotriazole thioamide 269 followed by cyclization of 270 using Burgess reagent (Scheme 108) <1998TL2861>. 

Thioacylation of Alcohols and Phenols with Thioacyl Halides... 

Thioacyl halides are not easily accessible. Aliphatic derivatives, in particular, can only be isolated in rare cases. Thioacylations of alcohols are therefore less important as synthetic methods than acylation of thiols with acyl hdides. Nevertheless, a variety of 0-alkyl and 0-aryl arenecarbothioates (2) have been obtained according to equation (4i).6.i4,25,2s... 

The utility of various thioxo- and dithio-carboxylic anhydrides was recently reviewed by Martin and Bamikow, who pointed out that bisthioacylthioanhydrides and the mixed anhydrides of thiocarbox-ylic and diphenyldithiophosphinic acids are effective thioacylating agents for alcohols (equation 46), whereas carboxylic dithiocarboxylic anhydrides transfer an acyl group to a nucleophile. 

Thiols can also be thioacylated, in the same way as alcohols (Section 2.5.3.2), by reaction with bis-thioacyl thioanhydrides (equation 58). The preparation of aromatic as well as aliphatic thioanhydrides is possible according to novel procedures described by Kato et a/., e.g. from the corresponding dithiocarboxylic acids and DCC or 2-chloro-N-methylpyridinium iodide.Even sterically hindered di-thioesters are obtained (equation 58). ... 

In general, thiocarbonyl halides (59) function as thioacylation reagents with a variety of nucleophiles to yield the appropriate thio derivatives (60) (Scheme 31). For example, (59) on condensation with thiols, amines, potassium cyanide or potassium thiocyanide yields the corresponding thio compounds (60). Thiolocarboxylic acids (50) characteristically acylate alcohols and amines with desulfuration (Scheme 32). Dithiocarboxylic acid esters (54b) react with organolithium or Grignard reagents to give the dithioketals (61) after treatment with an alkyl halide (Scheme 33). 

M. E. Jung, D. Sim, Stereoselective production of ( -amino alcohols and p-thioacyl alcohols via an application of the non-aldol aldol process. Tetrahedron Lett. 40 (1999) 8343. 

Photolysis of 3-phenyl-5(4H)-isoxazolone yields 2,5-diphenylpyrazine in 67% yield. Singlet excited isoxazol-5-one (224) undergoes both decarbonylation and decarboxylation to carbene intermediates, both of which are captured by alcohol or amine solvents. With triplet sensitisers an oxaziridine intermediate reacts with the solvent. N-Acylisoxazol-5-ones decarboxylate to yield singlet carbenes (225) which cyclise at the acyl oxygen to yield the isoxazoles (227), and the isothiazoles (228) are obtained via thioacyl carbenes (226) from N-thioacylisazol-5-ones. " The isolation of (229) as the main product from irradiation of benzophenone/N,N-dimethylaniline in the presence of the non-polymerising... 

Selenothioic acid Sc-esters serve as thioacylating agents toward amines and alcohols. Similarly, selenothioic acid S-esters and diselenoic acid esters can be used as selenoacylation agents. In addition, their thiocarbonyl and selenocar-bonyl groups act as dienophiles. The reactions of S-substituted selenothioates with electrophiles under basic conditions were investigated in detail. 

A variety of thioketones have found applicability in the synthesis of heterocyclic compounds. Chloro-thioacetone reacted with trialkoxy-phosphines to give thiirans. Thiophens have been prepared from mono-thio-j3-diketones, j8-thioketo-esters, > and from a-thioketo-acids. a-Thioacyl-y-lactones and -thiolactones rearrange in acid alcoholic solution to give dihydrofurans and dihydrothiophens, respectively. The simultaneous action of carbon disulphide, sulphur, and triethylamine on aliphatic thioketones gave mixtures of l,2-dithiole-3-thiones and 1,3-dithiole-2-thiones. The formation of thio-ozonides (1,2,4-trithiolans) by... 

S.3.2 Thioacylation of Alcohols and Phenols with Anhydrides, Thioketenes, Thioesters and Dithioesters... 

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