Thiocarbonyl compounds amide synthesis

Bis-(4-methoxyphenyl)-[l,3,2,4]dithiadiphosphetane 2,4-disulfide, transforms the carbonyl groups of ketones, amides and esters into the corresponding thiocarbonyl compounds. Cf. Knorr thiophene synthesis. 

More stable than many other thiocarbonyl compounds, thioamides have been known and used for a long time. Reliable methods of synthesis [119] were introduced as early as 1815 by Gay-Lussac for the reaction of nitriles with hydrogen sulfide and 1878 by Hoffman for the thionation of amides by means of tetraphosphorus decasulfide. 

Makino et al.35 developed a solid-phase synthesis of 1,3-disubstituted 2-thioxoquinazoline-4-ones using HMP Lanterns that were derivatized with a 4-aminobenzoate ester. Following the assembly of amide 25 (Scheme 9), SnAt reaction with alkyl amines gave support-bound products 26 with high conversion. The key thiocarbonylation step was achieved with thiocarbo-nyldiimidazole in decalin at 95° for 16 h in the presence of DMAP to afford 1,3-disubstituted 2-thioxoquinazoline-4-ones 27. The target compounds 28... 

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