2,5-Dioxopyrrolidin-1-yl 4-cyano-4-(((ethylthio)carbonothioyl)thio)pentanoate synthesis

Yield:1195771-65-3 79%

Reaction Conditions:

with dicyclohexyl-carbodiimide in chloroform at 0 - 20; for 23 h;

Steps:

Preparation of NHS-CEPA

To a solution of CEPA (1.00 g, 3.79 mmol) in CHCl₃ (20 mL) at 0 °C were added NHS (524 mg, 4.55 mmol) and DCC (940 mg, 4.55 mmol). The reaction mixture was stirred at 0 °C for 1 h and then at room temperature for 22 hrs. The by-product, dicyclohexylurea (DCU) was filtered off and the filtrate was concentrated in vacuo. The crude product was purified by flash column chromatography using ethyl acetate and hexane (3: 1 to 1: 1) as the eluents, and the resulting product NHS-CEPA was obtained (1.08 g, 79.0%) as a yellow powder. ¹H-NMR (400 MHz, CDCl₃, ppm):δ= 3.36 (2H, q, J= 8.0 Hz, -CH₂-S), 2.97-2.90 (2H, m, -CH₂-), 2.85 (4H, s, -CH₂-CH₂-), 2.71-2.48 (2H, m, -CH₂-), 1.89 (3H, s, -CH₃), 1.38 (3H, t, J= 8.0 Hz, -CH₃).

References:

Chen, Tao;Xu, Zhenkai;Zhou, Lei;Hua, Laiyu;Zhang, Shuo;Wang, Jiping [Tetrahedron Letters,2019,vol. 60,# 5,p. 419 - 422] Location in patent:supporting information