反应详情

A solution of {benzyloxycarbonyl-[2-(1,3-dioxo-1,3-dihydro-isoindol-2-ylamino)-ethyl]-amino}-acetic acid ethyl ester (0.22 g, 0.52 mmol) in diphenyl ether (3 mL) is heated to reflux for 2 h. Diphenyl ether is removed by vacuum distillation and the residue is purified by flash silica gel chromatography (2:1:1 to 1:1:1 heptane:DCM:EtOAc gradient elution) to afford 4-(1,3-dioxo-1,3-dihydro-isoindol-2-yl)-3-oxo-piperazine-1-carboxylic acid benzyl ester as a solid (0.126 g, 64%). MS: 380 (M+H); 1H NMR (300 MHz, CDCl3) δ 7.86-7.95 (m, 2H), 7.75-7.86 (m, 2H), 7.24-7.42 (m, 5H), 5.20 (s, 2H), 4.42 (s, 2H), 3.90-4.05 (m, 2H), 3.65-3.87 (m, 2H).

1. temperatureto reflux for 2 h
2. customDiphenyl ether is removed by vacuum distillation
3. customthe residue is purified by flash silica gel chromatography (2:1:1 to 1:1:1 heptane:DCM:EtOAc gradient elution)