4-chloro-2-(Methylthio)-5,6,7,8-tetrahydroquinazoline synthesis

Yield:51660-11-8 43%

Reaction Conditions:

with trichlorophosphate at 110;

Steps:

14 Preparation 14; 2-Hydrazino-5,6, 7, 8-tetrahydroquinazoline

To a mixture of ethyl 2-cyclohexanonecarboxylate (3.00 g, 17.6 mmol) and 2-methyl-2- thiopseudourea sulfate (3.68 g, 13.2 mmol) was added a solution of potassium carbonate (7.31 g, 52.9 mmol) in water (60 mL). The reaction solution was stirred at room temperature for 16 h, at which time it was observed to be a suspension. The white solid was collected by vacuum filtration, washed with water, and dried in vacuo. A mixture of the solid in phosphorus oxychloride (20 mL) was heated at [110°C] in a sealed tube, at which time it was observed to be a solution. The solution was cooled to room temperature and was then poured over cracked ice and water (300 [ML).] The mixture was vigorously stirred at 0°C for 1 h, and the resulting precipitate was collected by vacuum filtration, washed with water, and dried in vacuo to afford 1.61 g of 2-thiomethyl-4-chloro-5, 6,7, 8-tetrahydroquinazoline (43%) as an off-white solid. To a solution [OF 2-THIOMETHYL-4-CHLORO-5,] 6,7, 8-tetrahydroquinazoline (0.5121 g, 2.39 mmol) in a 10: [1] mixture of MeOH-HOAc (30 mL) was added activated zinc dust (500 mg, 7.65 mmol). The mixture was heated at [70°C] for 1 h, and was then cooled to room temperature and filtered. The resulting solution was concentrated in vacuo, and azeotropically dried with toluene (50 mL). The residue was partitioned between EtOAc (150 mL) and 1 N aq. [HC1] (50 mL), and the organic phase was then washed with saturated aq. [NAHCO3] and brine. The organic phase was then dried over anhydrous [MGSO4] and concentrated in vacuo to provide 0.1461 g of 2- thiomethyl-5,6, 7,8-tetrahydroquinazoline (34%) as a purple oil. To a solution of 2-thiomethyl-5, 6,7, 8-tetrahydroquinazoline (0.1461 g, 0.81 mmol) in [CH2CL2] (5 mL) was added m-chloroperbenzoic acid (0.462 g, 2.68 [MMOL).] The solution was stirred at room temperature for 3 h at which time it was observed to be a suspension. The solvent was then removed in vacuo, and [MEOH] (5 [ML)] was added followed by hydrazine monohydrate (1 mL, 20.6 mmol). The solution was then heated at [50°C] and stirred for 16 h. The solution was cooled to room temperature and purified by reverse phase HPLC to give 0.1126 g of the title compound [(85%)] as a colorless oil. MH+ 165.

References:

WO2003/101442,2003,A1 Location in patent:Page 55