Acetic Anhydride → HCID 53940189, compound

Participants

Reaction Steps

To a solution of 0.310 g of the above-obtained 5-[(R)-2- acetoxy-1-(trifluoroacetylamino)ethyl]imidazo[5,1-b]thiazole in 10 ml of methanol was added a solution of 0.160 g of sodium hydroxide in 5 ml of water, and the mixture was stirred at room temperature for 14 hours. The reaction solution was concentrated to dryness under reduced pressure to give a solid containing 5-[(R)-1-amino-2-hydroxyethyl]imidazo[5,1-b]-thiazole. To this was added 50 ml of methylene chloride, and the mixture was thoroughly stirred. To this suspension was added with ice-cooling a mixture of 2.0 g of acetic anhydride and 0.5 g of formic acid, which had been heated to 50° C. for 10 minutes and then cooled to room temperature. The mixture was stirred at room temperature for 30 minutes, and then cooled with ice. To this were added 4 ml of water and 4 g of potassium carbonate, and the mixture was stirred at room temperature for 30 minutes. To this mixture was added 4 ml of methanol, and the resulting mixture was stirred for an additional one hour. The organic layer was separated by decantation. The aqueous layer containing the crystals was washed with methylene chloride (30 ml×3). The combined organic layers were dried over anhydrous magnesium sulfate, and then concentrated to dryness to give 0.200 g (quant.) of 5-((R)-1-formylamino-2-hydroxyethyl)imidazo[5,1-b]thiazole. NMR (DMSO-d6) d: 3.88 (2H, t, J=5.8 Hz), 5.01 (1H, t, J=5.8 Hz), 5.27 (1H, dr, J=8.4 Hz, 5.8 Hz), 6.97 (1H, s), 7.22 (1H, d, J=4.2 Hz), 7.80 (1H, d, J=4.2 Hz), 8.08 (1H, s), 8.61 (1H, d, J=8.4 Hz) MS (EI, DMSO, 200° C.): 211 (M+)

Provenance & Evidence