Phosphorus oxychloride → (4-chloro-6,7,8,9-tetrahydro-5H-10-thia-1,3-diaza-benz[a]azulen-2-yl)-acetic acid ethyl ester

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Reaction Steps

The POCl3 (20 ml, 215 mmol)) was added to (4-hydroxy-6,7,8,9-tetrahydro-5H-10-thia-1,3-diaza-benz[a]azulen-2-yl)-acetic acid ethyl ester (5.5 g, 0.01795 mol) and the solution was refluxed for 2 h. The reaction was quenched into 200 g of ice and extracted with 3×100 ml ethyl acetate. The combined organic layers were dried over sodium sulphate and concentrated under vacuum. The crude was purified by chromatography on silica gel using 10% ethyl acetate in hexanes to give (4-chloro-6,7,8,9-tetrahydro-5H-10-thia-1,3-diaza-benz[a]azulen-2-yl)-acetic acid ethyl ester (2 g, 34%) as a pale yellow solid. 1H NMR (400 MHz, CDCl3): δ 4.19 (q, 2H), 4.02 (s, 2H), 3.30-3.37 (m, 2H), 2.92-2.98 (m, 2H), 1.85-1.95 (m, 2H), 1.65-1.78 (m, 4H), 1.25 (t, 3H); LC-MS: [M+H]=325.0 & 327.1 m/z.

Provenance & Evidence