Hydrochloric Acid → (4-Oxo-5-phenyl-3,4-dihydrothieno[2,3-d]pyrimidin-2-yl)acetic acid ethyl ester

Reaction equation

Cl.C(O[C:5]([C:7]1[C:11]([C:12]2[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=2)=[CH:10][S:9][C:8]=1[NH2:18])=[O:6])C.[C:19]([CH2:21][C:22]([O:24][CH2:25][CH3:26])=[O:23])#[N:20]>>[CH2:25]([O:24][C:22](=[O:23])[CH2:21][C:19]1[NH:20][C:5](=[O:6])[C:7]2[C:11]([C:12]3[CH:13]=[CH:14][CH:15]=[CH:16][CH:17]=3)=[CH:10][S:9][C:8]=2[N:18]=1)[CH3:26]

Participants

Reactant 3

HCID 313Hydrochloric Acid

HCID 7764Ethyl cyanoacetate

HCID 73242Ethyl 2-amino-4-phenylthiophene-3-carboxylate

Product 1

HCID 13591037(4-Oxo-5-phenyl-3,4-dihydrothieno[2,3-d]pyrimidin-2-yl)acetic acid ethyl ester

Procedure

Hydrogen chloride gas was bubbled through a stirred reaction mixture of 2-amino-4-phenylthiophene-3-carboxylic acid ethyl ester (4.94 g, 0.02 mol) in ethyl cyanoacetate (50 ml) for 2 hours. A thick suspension formed initially which slowly dissolved on gentle warming. The mixture was allowed to stand at ambient temperature for 18 hours. Excess hydrogen chloride was removed by bubbling nitrogen through the reaction mixture and most of the excess ethyl cyanoacetate was distilled out at reduced pressure. The solid residue was recrystallised from ethanol to give (4-oxo-5-phenyl-3,4-dihydrothieno[2,3-d]pyrimidin-2-yl)acetic acid ethyl ester (3.64 g), which was used without further purification.