Synthesis
General procedure for the synthesis of 2,3,6,7-tetrahydro-1H-azepine-1,4-dicarboxylic acid 1-tert-butyl ester 4-ethyl ester from the compound (CAS: 912444-88-3): Example 42C (0.77 g, 2.1 mmol) was dissolved in 30 mL of benzene, DBU (0.9 mL) was added, and the reaction was carried out for 1 hr at 60 °C. Upon completion of the reaction, the reaction mixture was cooled, concentrated, and the residue was purified by fast column chromatography (eluent: 30% EtOAc in hexane solution) to afford the target product 2,3,6,7-tetrahydro-1H-azepine-1,4-dicarboxylic acid 1-tert-butyl ester 4-ethyl ester (540 mg, 95% yield). m/z MS (DCI/NH3) m/z 270 (M + H) +.
References
[1] Patent: US2006/229289, 2006, A1. Location in patent: Page/Page column 22
[2] Angewandte Chemie - International Edition, 2013, vol. 52, # 23, p. 6072 - 6075
[3] Angew. Chem., 2013, vol. 125, # 23, p. 6188 - 6191
[4] Patent: US2018/258065, 2018, A1. Location in patent: Paragraph 0149
[5] Tetrahedron Letters, 2018, vol. 59, # 52, p. 4611 - 4615
