Yield:6036-64-2 63.5%

Reaction Conditions:

Stage #1: ethyl malonamate;guanidine hydrochloridewith acetic acid in ethanol at 65; pH=5; for 12 h;
Stage #2: with sodium hypochlorite in ethanol;
Stage #3: with acetic anhydride;potassium nitrate in ethanol; for 0.5 h;Cooling with ice;Reagent/catalyst;Solvent;

Steps:

1 Preparation of 6-chloro-5-nitro-2,4-diaminopyrimidine

EXAMPLE 1
Preparation of 6-chloro-5-nitro-2,4-diaminopyrimidine
A mixture of 100 mg (1.04 mmol) guanidine hydrochloride, 164 mg (1.25 mmol) ethyl carbamoylacetate (a molar ratio of guanidine hydrochloride and ethyl carbamoylacetate being 1:1.2), and 45 mL ethanol was added to a 100 mL flask.
Acetic acid was added slowly to the mixture to a pH of about 5 under stirring, and the mixture was heated at 65° C. for 12 hours. 37 mg NaClO (0.50 mmol) was then added to the mixture, and the mixture was continued to heat at 65° C. for 2 hours.
The mixture was cooled to room temperature, and 162 mg (1.51 mmol) potassium nitrate and 31 mg (0.31 mmol) acetic anhydride (a molar ratio of potassium nitrate and acetic anhydride being 5:1) were added to the mixture under an ice water bath.
The mixture was stirred under the ice water bath for 30 minutes.
The reaction was monitored by thin layer chromatography.
When the reaction was complete, the solvent in the mixture was removed under reduced pressure.
The mixture was then filtered, washed with ethanol to give a crude product.
The crude product was recrystallized in 40 mL ethanol to give 125.1 mg (0.66 mmol) 6-chloro-5-nitro-2,4-diaminopyrimidine, a yield of 63.5%.

References:

US10329261,2019,B1 Location in patent:Page/Page column 3-8