Yield:-

Reaction Conditions:

with sodium hydroxide;ethanol;water for 24 h;Heating / reflux;

Steps:

1.16.3

Step 3. 5,6,7,8-Tetrahydro-pyrido[4',3':4,5]thieno[2,3-d]pyrimidine; To a solution of 5,8-dihydro-6H-pyrido[4',3':4,5]thieno[2,3-d]pyrimidine-7- carboxylic acid ethyl ester (800 g, 3.0 mmol) in EtOH (15 mL) is added water (10 mL) followed by the addition of NaOH (600 mg, 15 mmol, 5 eq.). The resulting mixture is refluxed for 24 h. The reaction mixture is cooled to rt, and EtOH is evaporated under reduced pressure. The residue is extracted with DCM (2 x 20 mL), and washed with brine. The combined organics are dried over sodium sulfate. The solvent is removed under reduced pressure to yield a residue which is purified through chromatography eluting with DCM/MeOH (90:10) to give the title compound. MS (+VE) m/z 192.2 (M⁺+l).

References:

WO2009/3003,2008,A2 Location in patent:Page/Page column 72