51660-11-8

34170-21-3

51660-11-8

GENERAL STEPS: To a mixture of ethyl 2-cyclohexanone carboxylate (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 mixture was stirred at room temperature for 16 h to form a suspension. The white solid product was collected by vacuum filtration, washed with water and dried under vacuum. The dried solid was dissolved in phosphoryl chloride (20 mL) and heated at 110 °C in a sealed tube until completely dissolved. After cooling to room temperature, the reaction solution was slowly poured into a mixture of crushed ice and water (300 mL). It was stirred vigorously at 0 °C for 1 h. The precipitate was collected by vacuum filtration, washed with water and dried under vacuum to give 1.61 g of 2-methylthio-4-chloro-5,6,7,8-tetrahydroquinazoline (43% yield) as an off-white solid. 2-Methylthio-4-chloro-5,6,7,8-tetrahydroquinazoline (0.5121 g, 2.39 mmol) was dissolved in a 10:1 solvent mixture of methanol-acetic acid (30 mL), and activated zinc powder (500 mg, 7.65 mmol) was added. The mixture was heated at 70 °C for 1 h and then cooled to room temperature and filtered. The filtrate was concentrated in vacuum and residual water was removed by azeotropy with toluene (50 mL). The residue was partitioned between ethyl acetate (150 mL) and 1N aqueous hydrochloric acid (50 mL), and the organic phase was washed sequentially with saturated aqueous sodium bicarbonate and brine. The organic phase was dried with anhydrous magnesium sulfate and concentrated in vacuum to give 0.1461 g of 2-methylthio-5,6,7,8-tetrahydroquinazoline (34% yield) as a purple oil. 2-Methylthio-5,6,7,8-tetrahydroquinazoline (0.1461 g, 0.81 mmol) was dissolved in dichloromethane (5 mL) and m-chloroperbenzoic acid (0.462 g, 2.68 mmol) was added. The suspension was stirred for 3 h at room temperature. After removing the solvent under vacuum, methanol (5 mL) and hydrazine monohydrate (1 mL, 20.6 mmol) were added. The mixture was heated and stirred at 50 °C for 16 hours. After cooling to room temperature, it was purified by reversed-phase HPLC to give 0.1126 g of 4-chloro-5,6,7,8-tetrahydro-2-(methylthio)quinazoline (85% yield) as a colorless oil. Mass spectrometry analysis showed [M+H]+ peak at m/z 165.