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ChemicalBook CAS DataBase List 4-methyl-5-(4-methyl-1,3-oxazol-5-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione
170959-40-7

4-methyl-5-(4-methyl-1,3-oxazol-5-yl)-2,4-dihydro-3H-1,2,4-triazole-3-thione synthesis

3synthesis methods
-

Yield:170959-40-7 53%

Reaction Conditions:

Stage #1: 4-methyl-1,3-oxazole-5-carboxylic acid;4-methylthiosemicarbazidewith 2-propane phosphonic acid anhydride;N-ethyl-N,N-diisopropylamine in ethyl acetate;N,N-dimethyl-formamide at 0 - 20; for 6.33333 h;
Stage #2: with sodium hydroxide in water at 70; pH=11;
Stage #3: with hydrogenchloride in water; pH=5; for 8 h;Product distribution / selectivity;

Steps:

123(1B)

4-Methyl-1.S-oxazole-δ-carboxylic acid (prepared according to the method of Preparation 1A, 12.9 g) was dissolved in DMF (60 mL) and treated with 4-methyl-3-thiosemicarbazide (11.61 g). Then disopropylethylamine (DIPEA) (31.OmL) was added at 2O0C. Under ice bath cooling, T3P 50% w/w in ethyl acetate (90 mL) was added drop wise, maintaining the temperature below 150C over 20 minutes. The resulting mixture was then stirred at 2O0C for 6 hours. EPO The mixture was diluted with NaOH 4 M (120.0 ml_). The resulting bi-phasic mixture was allowed separating and the upper organic layer discarded. The aqueous layer (pH = 8) was adjusted to pH = 11 with additional NaOH 4 M (60 ml.) and then heated to 7O0C (internal temperature) for 30 minutes. After cooling down over night, HCI 37% was slowly added until pH=5 was reached. The suspension was stirred for 8 hours, then the solid was filtered and washed with water (60 ml_), and it was dried in a vacuum oven at 4O0C overnight. The title compound was obtained in a 53% theoretical yield (10.48 g).NMR (I H, DMSO-d6, δ ppm): 14.1 1 (bs, 1 H), 8.60 (s, 1H), 3.61 (s, 3H), 2.33 (s, 3H) MS (m/z): 197[MH]+

References:

WO2007/22980,2007,A1 Location in patent:Page/Page column 131; 132