4-Ethoxycarbonylthiolan-3-one

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of formamidine HCl salt (3.70 g, 46.0 mmol) in ethanol (200 mL) was added NaOEt in ethanol (21% wt, 17.2 mL, 46.0 mmol). The mixture was stirred at room temperature for 1 hour. The ethyl 4-oxotetrahydrothiophene-3-carboxylate (8.0 g, 46.0 mmol) was added. The mixture was stirred at room temperature for 4 hours and then refluxed overnight. After cooling, the solvent was removed and the residue was washed with a small amount of water and CH2Cl2 to afford 5,7-dihydrothieno[3,4-d]pyrimidin-4-ol as light brown solid (2.5 g, 35%). 1H NMR (d6-DMSO, 400 MHz) δ 12.59 (s, 1H), 8.13 (s, 1H), 4.12 (s, 2H), 3.96 (s, 2H). MS (APCI+) [M+H]+ 155. The mixture was stirred at room temperature for 4 hours refluxed overnight After cooling the solvent was removed the residue was washed with a small amount of water and CH2Cl2

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 4-chloro-2,5-difluorobenzenecarboxamidine, ethyl 4-oxotetrahydrothiophene-3-carboxylate, NaOMe, and MeOH was stirred at ambient temperature for 19 hours and then at 60° C. for 5 hours to yield 2-(4-chloro-2,5-difluorophenyl)-5,7-dihydrothieno[3,4-d]pyrimidin-4(1H)-one.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 20 parts by weight of methyl 3-keto-1,5-dihydrothiophene-4-carboxylate, 57.8 parts by weight of ethanol and 1 part by weight of p-toluenesulfonic acid are refluxed for 50 hours, and the mixture is then distilled. 17.1 parts by weight of ethyl 3-keto-1,5-dihydrothiophene-4-carboxylate of melting point 106°-109° C./1.3 mbar are obtained. the mixture is then distilled

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of formamidine HCl salt (3.70 g, 46.0 mmol) in ethanol (200 mL) was added NaOEt in ethanol (21% wt, 17.2 mL, 46.0 mmol). The mixture was stirred at room temperature for 1 hour. The ethyl 4-oxotetrahydrothiophene-3-carboxylate (8.0 g, 46.0 mmol) was added. The mixture was stirred at room temperature for 4 hours and then refluxed overnight. After cooling, the solvent was removed and the residue was washed with a small amount of water and CH2Cl2 to afford 5,7-dihydrothieno[3,4-d]pyrimidin-4-ol as light brown solid (2.5 g, 35%). 1H NMR (d6-DMSO, 400 MHz) δ 12.59 (s, 1H), 8.13 (s, 1H), 4.12 (s, 2H), 3.96 (s, 2H). MS (APCI+) [M+H]+ 155. The mixture was stirred at room temperature for 4 hours refluxed overnight After cooling the solvent was removed the residue was washed with a small amount of water and CH2Cl2

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 4-chloro-2,5-difluorobenzenecarboxamidine, ethyl 4-oxotetrahydrothiophene-3-carboxylate, NaOMe, and MeOH was stirred at ambient temperature for 19 hours and then at 60° C. for 5 hours to yield 2-(4-chloro-2,5-difluorophenyl)-5,7-dihydrothieno[3,4-d]pyrimidin-4(1H)-one.