Application of the phthalimidine synthesis with use of 1,2,3-1H-benzotriazole and 2-mercaptoethanol as dual synthetic auxiliaries .1. A simple synthesis of (+/-)-indoprofen

A representative nonsteroidal anti-inflammatory drug indoprofen is prepared in 4 steps from the commercially available 2-(4-nitrophenyl)propanoic acid. The key step is the mild phthalimidine synthesis by the double Mannich condensation of o-phthalaldehyde with ethyl 2-(4-aminophenyl)propanoate with use of 1,2,3-1H-benzotriazole and 2-mercaptoethanol as dual synthetic auxiliaries.