Hydrochloric Acid → Ethyl 5-amino-2-methylthiazole-4-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Add acetoamidocyanoacetate (1000 g, 5.88 mol) to a 22 L 3-necked RB flask equipped with reflux condenser, thermometer, mechanical stirrer then add toluene (12L). Add to this suspension at RT Lawesson's reagent (1187 g, 2.93 mol). Stir the resulting yellow slurry at 70° C. for 16 h, cool to RT. Pour the top yellow solution away from the gummy material on the bottom of the flask into a separation funnel. Add 1N HCl solution (2.5L) and TBEA (2.5L) and stir the mixture. After 15 min., combine the bi-phase solution was into the toluene solution in the funnel. Gummy material maybe left in the flask. Repeat the above procedure again. Separate the aqueous and wash the combine organic solution with 1N HCl (2×2.5L). Separate the organic layer and combine the aqueous and basify with 2N KOH solution. Add ethyl acetate (3×4L) and extract the product. Combine the organic layer, dry over anhydrous sodium sulfate, and evaporate to give 552 g as a pale yellow solid. Dissolve the remaining gummy in methanol (1L) and evaporate to dryness. Add MTBE (2.5L) and 1N HCl (4 L) and stir the mixture. After 15 min., separate the organic layer and basify the aqueous with 2N KOH solution Extract the product with ethyl acetate (2×2L). Combine the organic layers and dry over anhydrous sodium sulfate and evaporate to give 165 g as a pale yellow solid. (Total: 717 g, 65%). Mass spectrum (m/e): 187(M+1); 1HNMR(300 MHz, DMSO-d6, ppm): δ 1.21(t, 3H), 2.38(s, 3H), 4.21(q, 2H), 7.21(bs, 2H). 13CNMR(75 MHz, DMSO, ppm): δ 15.1, 19.2, 59.8, 119.3, 145.6, 161.7, 164.1. Formula: C7H10N2O2S.

Herkunft & Nachweise