5-Thiazolecarboxylic acid, 4-methyl-, ethyl ester

white to light yellow crystal powde

Compound 3a (4.0 g, 21.5 mmol) was dissolved in 106 ml of 30percent H3PO2.Cool to -5 ° C, NaNO2 (3.0 g, 2.0 eq) was dissolved in 12 ml of water.Add dropwise to the reaction solution, After the addition is completed, Transfer to 0 ° C for 1 h, stir at room temperature for 2 h, Cold NaOH (17g, dissolved in 200ml water) is slowly added dropwise.Saturated NaHCO3 solution is neutral, Extracted with Et2O (50mlx3), Column chromatography (PE: EA=50:1v/v), A yellow semisolid 3b (2.1 g, 56percent) was obtained.3L reaction flask with mechanical stirring, Thermometer and constant pressure dropping funnel, Under ice-water bath, 2.5 L of tetrahydrofuran, 135.6 g phosphorus sulfide, Control temperature below 10 , 50g formamide was added dropwise, Warmed to room temperature, The reaction for 2 hours.Concentrate to dryness under reduced pressure.The solid was dissolved with 5percent NaOH solution, Extracted five times with ethyl acetate, Each 300mL.The combined organic layers, Rinse once with saturated brine, Dried over anhydrous sodium sulfate, filter, concentrate, Have a yellow oily liquid 55g.

Molecular Weight:171.22
XLogP3:1.9
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:3
Exact Mass:171.03539970
Monoisotopic Mass:171.03539970
Topological Polar Surface Area:67.4
Heavy Atom Count:11
Complexity:151
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes