[Br:1][C:2]1[C:3](=[O:10])[N:4]([CH3:9])[C:5](=[O:8])[NH:6][N:7]=1.[S:11]1[CH:15]=[CH:14][CH:13]=[C:12]1[CH2:16][CH2:17]O.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.CCOC(/N=N/C(OCC)=O)=O>C1COCC1.C1(C)C=CC=CC=1>[Br:1][C:2]1[C:3](=[O:10])[N:4]([CH3:9])[C:5](=[O:8])[N:6]([CH2:17][CH2:16][C:12]2[S:11][CH:15]=[CH:14][CH:13]=2)[N:7]=10.4 g (1.94 mmol) of intermediate 2a are placed in the presence of 0.24 mL (2.14 mmol) of 2-thiophen-2-yl-ethanol, 0.61 g (2.33 mmol) of triphenylphosphine in 4 mL of THF. At 0° C., 0.54 mL (2.33 mmol) of DEAD in solution in toluene are added dropwise. The reaction medium is heated for 7 h at 70° C. After concentration, the obtained residue is taken up with ethyl acetate and washed with water. After drying on MgSO4, the organic phase is dry concentrated. The obtained residue is purified by flash chromatography on silica (CH2Cl2/MeOH, gradient 100/0 to 97/3 over 30 min). 0.48 g of crystals corresponding to the compound 4k are obtained (yield: 79%).
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