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Example 1 Synthesis of 2-(2,6-Dichlorophenylamino)-1H-imidazo[4,5-f]quinazoline-7,9(6H,8H)-dione To a solution of 6-chloroanthranilic acid (1.72 g, 10 mmol) and NaOH (0.40 g, 10 mmol) in water (15 mL) was added sodium cyanate (0.72 g, 11 mmol), followed by acetic acid (0.66 g, 11 mmol). The solution was stirred for 9 h, and then acidified with conc. HCl. The precipitate was filtered off and washed with water. The wet solid was added to a solution of NaOH (8.0 g, 200 mmol) in water (60 mL) and stirred for 20 h. The precipitate was filtered off and suspended in water (80 mL), then heated to boiling and acidified with 50% H2SO4. The cooled mixture was filtered, the solid washed well with water and dried to give 5-chloroquinazolin-2,4-dione (1.42 g, 72%).
With urea; In methanol;
a) A mixture of 2.0 g (11 mmol) of 2-amino-6-chlorobenzoic acid and 1.4 g (23 mmol) of urea was heated to 160 C. for 2 hrs. and at 180 C. for a further 2 hrs. The resulting brown mass was triturated with 200 ml of methanol, filtered off and dried in a vacuum. 1.2 g (53%) of 5-chloro-1,2,3,4-tetrahydroquinazoline-2,4-dione were obtained as white crystals; MS: me/e=196 (M+).
1-{2-deoxy-3-O-[2-cyanoethoxy(diisopropylamino)phosphino]-5-(4,4'-dimethoxytrityl)-β-D-erythro-pentofuranosyl}-5-chloro-quinazoline-2,4(3H)-dione[ No CAS ]
General procedure: Urea (29.0 g, 482.9 mmol) and 2-amino-5-fluorobenzoic acid (5.00 g, 32.20 mmol) were added sequentially to a 200 mL of sealed tube. The mixture was gradually warmed to 160 under vigorous stirring. After stirring for 4 h, the mixture was heated to 180 , and continued to react for 4 h. Then the mixture was cooled gradually to rt, and water (150 mL) was added. The resulting mixture was stirred for 1 h at rt, and filtered. The residue was washed with water until the filtrate was colorless, and then washed with acetone (20 mL) and methanol (70 mL) sequentially. The resulting residue was dried to give the title compound (as a brick red solid, 5.04 g, 87)
23
[ 78754-81-1 ]
[ 134517-55-8 ]
Yield
Reaction Conditions
Operation in experiment
In ice-water; trichlorophosphate;
b) 0.5 g (2.54 mmol) of 5-chloro-1,2,3,4-tetrahydroquinazoline-2,4-dione was suspended in 7 ml (96 mmol) of phosphorus oxychloride and heated to 120 C. for 24 hrs. The reaction mixture was left to cool to room temperature and poured on to ice-water. The brown precipitate was filtered off, dried and chromatographed over silica gel with methylene chloride as the eluent. 260 mg (44%) of 2,4,5-trichloroquinazoline were obtained as white crystals; MS: me/e=232, 234 (M+).
2-Amino-6-chlorobenzoic acid (300 mg, 1.75 mmol) and urea (1.1 g) were mixed in a Radley's carousel tube and heated to 170 C. for 18 h, during which time a melt formed. The melt was cooled to ambient temperature and suspended in water by sonication. The solid was collected by filtration, transferred to a conical flask and dissolved in hot 1N NaOH. The product was triturated with glacial acetic acid, filtered and washed with water. After drying under vacuum at 50 C. for 18 h the product was obtained as a light brown solid (351 mg, 100% crude yield). This material was carried forward without further purification. 1H NMR (DMSO): 11.10 (2H, br m), 7.54 (1H, t, J 8.1), 7.19 (1H, dd, J 7.8 and 1.0) and 7.12 (1H, dd, J 8.3 and 1.1).
0.5 mmol of 5-chloro-2,4-quinazolinedione was added to 20 mL of anhydrous acetonitrile, N.2Under the protection, 1.0 mL (4 mmol) of NO-BSA was added dropwise and reacted at 25 C for 2 h.(0.55 mmol) of 1-acetoxy-2,3,5-tribenzoyloxy-1-beta-D-ribofuranose and 0.2 mL (1.1 mmol) of TMSOTf were simultaneously added to the above solution, 50-60 C, reaction 20-24 h.The solvent was removed by steaming and saturated with NaHCO3And saturated aqueous solution of NaCl.Silica gel spin drying, column chromatography separation purification products.The product was a pale yellow solid.
The flask was charged with 12 mmol of 2-amino-6-chlorobenzoic acid, 65 mL of water and 1.5 mL of glacial acetic acid, and the mixture became a suspension.A solution of 2.36 g (28 mmol) of potassium cyanate in 10 mL of water was added dropwise to the above mixture and refluxed at 80-90 C for 1-2 h.Cooled to room temperature, 2.0 g (50 mmol) of sodium hydroxide was added to the suspension and reacted at 80-90 C for 3-5 h.The precipitate was formed, filtered, washed with water and dried to give a yellow solid in 79% yield.
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