Yield: 92%

Reaction Conditions:

Stage #1:2,4,6-trichloropyrimidine-5-carbaldehyde with hydroxylamine hydrochloride;acetic acid in water at 60; for 1 h;
Stage #2: with thionyl chloride at 20; for 2.16667 h;Reflux;

Steps:

2.2 Step 2. 2,4,6-trichioropyrimidin-5-formonitrile
Step 2.
2,4,6-trichloropyrimidin-5-formonitrile
2,4,6-trichloropyrimidin-5-carboxaldehyde (10 g, 47.4 mmol), hydroxylamine hydrochloride (3.3 g, 47.5 mmol), glacial acetic acid (100 mL), and H₂O (5 mL) were added to a 150-mL round-bottom flask, and heated to 60° C. to react for 1 hour.
After the completion of the reaction, the reaction solution was poured into crushed ice, and was extracted with CH₂Cl₂.
The resultant organic phases were combined, washed with a saturated NaCl solution, dried with anhydrous Na₂SO₄, and then filtered and concentrated.
The obtained substance was dissolved in SOCl₂ (60 mL), reacted at room temperature for 10 minutes, and then heated for a reflux reaction for 2 hours.
After the completion of the reaction, the resultant mixture was subjected to reduced pressure distillation to remove SOCl₂ to give a residue, which was then dissolved in EtOAc and washed with H₂O.
The resultant organic phase was dried with anhydrous Na₂SO₄, filtered, and concentrated to obtain an oily substance of 9 g.
The yield was 92%.

References:

Shenzhen Bo Li Jian Medicine Co., Ltd.;Ye, Baohuan US2019/255057, 2019, A1 Location in patent:Paragraph 0086; 0088