Acetic Acid → Tert-butyl 4-((2-bromo-5,5-dimethylcyclohex-1-enyl)methyl)piperazine-1-carboxylate

Participants

Reaction Steps

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).

Provenance & Evidence