Phosphorus oxychloride → Ethyl 2-chloro-4-phenyl-1,3-thiazole-5-carboxylate
Reaction equation
O=[C:2]1[NH:6][C:5]([C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)=[C:4]([C:13]([O:15][CH2:16][CH3:17])=[O:14])[S:3]1.P(Cl)(Cl)([Cl:20])=O>>[Cl:20][C:2]1[S:3][C:4]([C:13]([O:15][CH2:16][CH3:17])=[O:14])=[C:5]([C:7]2[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=2)[N:6]=1Participants
3
Procedure
To a solution of 20.0 g (0.105 mole) of ethyl β-amino-cinnamate in 40 ml. of chlorobenzene under ice cooling was added a solution of 11.6 g (0.112 mole) of chorocarbonylsulfenyl chloride in 10 ml. of chlorobenzene. The reaction mixture was heated at 110° C. for 2 hours, cooled to triturated with petroleum ether. The precipitate was heated with hot benzene, cooled and filtered to give 14.4 g (55%) of ethyl 2,3-dihydro-2-oxo-4-phenyl-5-thiazolecarboxylate as yellow needles. A mixture of 3.0 g (0.012 mole) of ethyl 2,3-dihydro-2-oxo-4-phenyl-5-thiazolecarboxylate and 14 ml. of phosphorus oxychloride was held at reflux for 24 hours and cooled. The reaction mixture was poured into ice water. The solid precipitate was extracted into ether. The ether solution was dried and concentrated under reduced pressure. The residue was recrystallized from hexane to give 2.2 g (68%) of ethyl 2-chloro-4-phenyl-5-thiazolecarboxylate, m.p. 56°-57° C.