XCIV.—Reactions of thiosemicarbazones. Part II. Action of esters of α-halogenated acids

New syntheses of thiadiazinones, thiazolidinedione hydrazones, and hydroxythiazoles from phenyl (trichloromethyl) carbinols

“…Recrystallization from aqueous ethanol gave 27 g of pure 5-phenyl-2,4-thiazolidinedione-2-isopropylidenehydrazone: 11.9 (broad s, 1, -NH-), 7.53 (s, 5, Ph), 5.48 12.80. 5-(_p-Methoxyphenyl)-2,4-thiazolidinedione 2-isopropylidenehydrazone (8d) was prepared in 31% yield from p-methoxyphenyl(trichloromethyl)carbinol13 as above. The material did not melt sharply; after repeated crystallization from aqueous ethanol, it melted at 169-175°when inserted in the melting point bath at 165°and the temperature raised at 2°/min: NMR (DMSO) 11.8…”

“…(broad s, 1, -NH-), 7.4-6.9 (quartet, 4, Ph), 5.35 (s, 1, >CH-), 3.82 (s, 3, -OCH3), 11.28. 4-Hydroxy-2-methyl-5-phenylthiazole (11). To a solution of 45 g (0.2 mol) of phenyl(trichloromethyl)carbinol and 30 g (0.38 mol) of thioacetamide in 250 ml of ethylene glycol was added 70 g (1.06 mol) of potassium hydroxide pellets in 200 ml of ethylene glycol over an 80-min period at 50°.…”

“…A third class of nucleophiles with the S=CNHfunction are the thioamides. Thioacetamide was allowed to react with phenyl(trichloromethyl)carbinol under the same conditions as before, and 4-hydroxy-2methyl-5-phenylthiazole (11) was isolated in 18% yield. The formation of the hydroxythiazole involves the attack of the thioenolate anion on the epoxide 2 in a manner strictly analogous to that given in Scheme I, followed by ring closure to 10 and enolization to 11.…”

Mechanistic Insights into the Formation of 1-Alkylidene/Arylidene-1,2,4-triazolinium Salts: A Combined NMR/Density Functional Theory Approach

“… 2 − 4 Compounds I – III were also soon identified as versatile starting materials in organic synthesis offering four distinct nucleophilic centers and thus allowing cascade reactions to give various heterocyclic compounds. 5 − 8 Even after more than 100 years of research, 9 unprecedented reaction outcomes of these starting materials have still been recently reported. 10 In contrast, isothiosemicarbazonium salts ( IV ; Scheme 1 A)—key intermediates for the preparation of the intensively studied isothiosemicarbazones ( III ) 11 − 16 —were thus far not extensively investigated for their use in cyclization reactions.…”

Synthesis of p-methylthiobenzyl chloride. Case of isomer control in an electrophilic substitution

“…Found: C, 51.42; H, 4.56; N, 14.74; Cl, 12.80. 5-(_p-Methoxyphenyl)-2,4-thiazolidinedione 2-isopropylidenehydrazone (8d) was prepared in 31% yield from p-methoxyphenyl(trichloromethyl)carbinol13 as above. The material did not melt sharply; after repeated crystallization from aqueous ethanol, it melted at 169-175°when inserted in the melting point bath at 165°and the temperature raised at 2°/min: NMR (DMSO) 11.8…”