反应详情

To a solution of 2-bromo-5,5-dimethyl-cyclohex-1-ene carbaldehyde (1 g, 4.61 mmol) in dichloromethane (70 ml) at rt under nitrogen was added glacial acetic acid (0.29 ml, 5.1 mmol) followed by piperazine-1-carboxylic acid tert-butyl ester (0.94 g, 5.07 mmol). The reaction was stirred for 1 h before sodium triacetoxyborohydride (2.05 g, 9.68 mmol) was introduced. After 16 h, a solution of 5% NaOH (20 ml) was added and the mixture was extracted with dichloromethane. The organic layer was separated and washed with H2O, dried (Na2SO4), filtered and concentrated under reduced pressure to give the crude product. Purification by column chromatography on silica eluting with 5% EtOAc/heptane provided 4-(2-bromo-5,5-dimethyl-cyclohex-1-enylmethyl)-piperazine-1-carboxylic acid tert-butyl ester (1.3 g, 73%).-1H NMR (MeOD) δ 3.44 (4H, br t), 3.14 (2H, br s), 2.55 (2H, br m), 2.40 (4H, br t), 2.08 (2H, br s), 1.51 (2H, t), 1.48 (9H, s), 0.93 (6H, s).

1. additionwas introduced
2. extractionthe mixture was extracted with dichloromethane
3. customThe organic layer was separated
4. washwashed with H2O
5. dry with materialdried (Na2SO4)
6. filtrationfiltered
7. concentrationconcentrated under reduced pressure
8. customto give the crude product
9. customPurification by column chromatography on silica eluting with 5% EtOAc/heptane