Sulfur-Containing Heterocycles Derived by Reaction of ω-Keto Amides with Lawesson's Reagent

Article abstract of DOI:10.1002/hlca.19980810531

The reaction of ω-keto amides with Lawesson's reagent (LR: 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide) is described. Treatment of 3-keto amides (2-acylacetamides) 1 with LR gave the corresponding 3-keto thioamides 2, along with 1,2-dithiole-3-thiones 3. Treatment of 4-keto amides, 3-acyl propionamides 5, with LR yielded five-membered heterocycles, pyrroles 6 and/or 2-aminothiophenes 7. 5-Keto amides, 3-benzoyl butyramides 8, reacted with LR to give dihydrothiopyran-2-thione 9 as the sole product, but in low yield. 2-Acylbenzamides 10 also reacted with LR to afford 3-mercaptoisoindolin-2-ones 11 or dihydroisobenzothiophene-1-thiones 12.