Thioamides acylating reagents

Adducts from Amides (Thioamides) and Acylating Reagents... 

An alternate step-wise cyclization strategy to form 3-carboline 22 is shown in Scheme 7. Acylation of D-tryptophan (21) with piperonyloyl chloride afforded amide 25, which was converted to thioamide 26 with Lawesson s reagent. Thioamide 26 was treated with methyl iodide in refluxing CH2CI2 to give a a-thiomethylimmonium ion, which was trapped by the intramolecular addition of indole. The thiomethyl group was... 

Table 13.21) or from amides by treatment with Lawesson s reagent. Thioamides can also be prepared on cross-linked polystyrene by the addition of H2S to nitriles (Entry 5, Table 13.21), by thiocarbamoylation of resin-bound organolithium compounds (Entry 6), or by the acylation of amines with reactive thio acid derivatives (Entry 7, Table 13.21). 

Keywords acyl chloride, 77-alkyl piperazine, Lawesson s reagent, microwave irradiation, thioamide... 

The diamine 2 was added to an etherial solution of an acyl chloride 1 in a Teflon-capped vial. Salt precipitaion was instant. The solvent was removed by filtration, where the Teflon cap served as the filter. Lawesson s reagent (1.0-1.5 equiv.) was added to the salt 3 and the resulting mixture of solids was mixed thoroughly and thereafter irradiated for 8 min in a domestic microwave oven (900 W, Whirlpool M401). Solid-phase extraction afforded the thioamides 4 in adequate purities and yields. 

Different synthetic methods which were used for amide and thioamide bond formation in solution synthesis were transferred in sohd-state ball-milling conditions. These include peptide-coupling reagents, addition of cumulenes, oxidative amina-tion, and acylation. 

Poly(3-acyl-2-oxazolone) is a highly selective acylating agent for amines. An improved method of preparation and the use of trimethylacetic formic anhydride as a selective iV-formylating reagent have been reported. Thioamides (250) are prepared by the reaction of the nitrile (249) with H2S (Scheme 127). ... 

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