Acetic Acid → Tert-butyl 4-cyclobutyl-1,4-diazepane-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of [1,4]diazepane-1-carboxylic acid tert-butyl ester (5 g, 24.97 mmol) in DCE (70 ml) at 20 to 25° C. was added cyclobutanone (1.75 g, 24.97 mmol) followed by acetic acid (1.5 g, 24.97 mmol) dropwise. The resulting mixture was stirred at 20 to 25° C. for ca. 2 h. Sodium triacetoxyborohydride (7.94 g, 37.46 mmol) was added in 9 portions, keeping the temperature in the range of 20 to 25° C. The resulting suspension was stirred at 20 to 25° C. overnight. Saturated aqueous NaHCO3 (80 ml) was added in four portions and the biphasic mixture stirred at 20 to 25° C. for ca. 0.5 h. The organic layer was separated, washed with water (20 ml) and the aqueous phase back extracted at pH 9 with DCM (20 ml). The combined organic phases were dried (Na2SO4), filtered and concentrated at reduced pressure to provide the title compound (6.1 g, 96% yield) as yellow oil.

Provenance & Evidence