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ChemicalBook CAS DataBase List 5-Chloromethyl-2H-1,2,4-triazolin-3-one
252742-72-6

5-Chloromethyl-2H-1,2,4-triazolin-3-one synthesis

2synthesis methods
5-ChloroMethyl-2,4-dihydro-[1,2,4]triazol-3-one is an intermediate mainly used in the synthesis of the antiemetics aprepitant hydrochloride and fosaprepitant. It was prepared from 5-Hydroxymethyl-2,4-dihydro[1,2,4]triazol-3-one with SOCl2 by stirring in anhydrous acetonitrile for overnight at room temperature.
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Yield:-

Reaction Conditions:

in methanol;toluene;

Steps:

1 3-Chloromethyl-1,2,4-triazolin-5-one

EXAMPLE 1 3-Chloromethyl-1,2,4-triazolin-5-one A mixture of semicarbzide hydrochloride (5.69 Kg, 51.0 mol), 2-chloro-1,1,1-trimethoxy ethane (94.0 mol) and methanol (54 L) was stirred at room temperature for 4 days. The solvent was then removed under reduced pressure and toluene (25 L) was added. The resulting slurry was cooled to 0° C. and filtered to afford 3-chloromethyl-1,2,4-triazolin-5-one (6.69 Kg, 98%) as a white solid (mp 197-199° C.); 1H NMR (d6 DMSO) δ=4.43 (2H, s, CH2), 11.48 (1H, s, NH) and 11.64 (1H, s NH); 13C NMR (d6 DMSO) δ=36.9 (ClCH2), 144.6 (CH2C=N) and 156.9 (NHCONH). The difficulty in following the reaction of such water soluble compounds has been overcome using the following HPLC conditions:

References:

US2003/187274,2003,A1

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