Thioacylating reagent

Coupling of Thioacylating Reagents with Amino Acids or Peptides ... 

New thioacylating reagents were developed. A combination of monothio-carboxylic acids with a PyBOP type reagent, containing phosphorus with a potential P=0 bond formation as the driving force [50, 51], works efficiently. A thionoacid derivative of nitrobenzotriazole provided a mild and race-misation free coupling with phenylalanine methyl ester [52]. This shows that this route is not a dead end as had been feared for some time [53]. 

The derivatives of nitrobenzotriazole a-aminothionic acids, used as thioacylating agents in the synthesis of thiopeptides and nitrobenzotriazole thioacylating reagents, have been obtained in a similar way (Scheme 2.119) (624, 625],... 

Thioacyl diphenylthiophosphinyl sulfides are useful thioacylating reagents too, which give dithioesters in good yields under mild reaction conditions (equation 60). ... 

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). 

Recently, a mild, efficient and racemization-free route for the incorporation of a thioamide linkage into a peptide either in solution or on solid phase was provided by Shalaby et al. [127], First, the N-Boc-amino acid anilide derivative was thionylated with P4St0 and subsequently activated by transformation to the benzotriazole derivative, affording a stable thioacylating reagent (Scheme 7.8) suitable for combinatorial syntheses. 

Thioacylation Reagent. The regioselective thioacylation of unprotected carbohydrates via the agency of dibutyltin oxide... 

Carboxymethyl dithiocarboxylates are well-known thioacylating reagents, and have been the starting materials for the preparation of thionocarboxylates of different types, > e.g. (179), which has proved to be an efficient sensitizer for photochemical reactions in the visible region (A < 500 nm), and... 

Hydroxypyridines may be thioacylated using benzotriazole reagents. The sodium salt of 3-hydroxypyridine reacts with aryloxythiobenzotriazole 97 to give thiocarbonate 98 in good yield <2005JOC7866> (Equation 66). 

It appears that the acylation products depend upon the structure of the starting material, the acylation reagents and the reaction conditions (see Section IV.C). It is relevant to the acylation that the 2-methyl group in 89 and 92 has also been thioacylated and esterified, respectively, but the reaction yields are low10,105. 

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>. 

In contrast to thioacyl chlorides, thiophosgene, CSCh, is readily accessible and conveniently handled making it an important reagent in the synthesis of thiocarbamoyl chlorides (15 ClCSNRa), 0-alkyl thiourethanes (ROCSNR 2), and thioureas (R2NCSNR2) (c/. Volume 6, Chapter 2.8). ... 

Dithiocarboxylates are particularly useful reagents in the thioacylation of the terminal amino group in peptides. Combination with a subsequent cleavage by anhydrous TEA results in a modified Edman degradation and a protocol has been worked out with conditions that are compatible with the ones required for an automatic sequential analysis (Scheme 4). ... 

---