53051-97-1

82514-58-7

53051-97-1

General procedure for the synthesis of 5,6-dihydro-4H-cyclopentathiazol-2-amines from 2-amino-5,6-dihydro-4H-cyclopentathiazole hydrochloride: 1. 2-Amino-5,6-dihydro-4H-cyclopentathiazole hydrochloride (16.5 g, 93 mmol) was added to a mixture of aqueous sodium bicarbonate (16.5 g dissolved in 250 mL of water) and 25% THF/EtOAc (160 mL, v/v). 2. The reaction mixture was stirred at room temperature for 15 minutes. 3. The mixture was filtered through a diatomaceous earth pad to clarify the mixture. 4. The organic layer was separated and dried over anhydrous magnesium sulfate and subsequently concentrated under vacuum to 47 g. The mixture was purified by adding toluene (100 mL). 5. Toluene (100 mL) was added and the mixture was again concentrated to 45 g under vacuum. 6. the mixture was diluted with heptane (40 mL), cooled and the product was collected by filtration and dried to afford 5,6-dihydro-4H-cyclopentathiazol-2-amine as the free base (10.75 g, 85% yield). Product characterization data: 1H NMR (CD3OD) δ 4.88 (2H, s), 2.75-2.70 (2H, m), 2.60-2.55 (2H, m), 2.39-2.33 (2H, m).