Ethyl Acetate → tert-Butyl 4-(3-oxobutanoyl)piperidine-1-carboxylate

Participants

Reaction Steps

A solution of 2.27 g (10.0 mmol) of 4-acetyl-1-(tert-butoxycarbonyl)piperidine (from Step A), 1.95 mL (20.0 mmol) of ethyl acetate and 2.24 g (20.0 mmol) of potassium t-butoxide in 25 mL of MTBE was stirred at rt for 20 h. The reaction was quenched with 50 mL of 0.5 N KHSO4 and extracted with 150 mL of ether. The extract was dried over MgSO4 and concentrated. Flash chromatography on 70 g of silica gel using 20:1 v/v hexanes/acetone as the eluant afforded the title compound. The enol form predominated in CDCl3 solution: 1H NMR (500 MHz, CDCl3) δ 1.46 (s, 9H), 1.53 (dq, J=4.5, 12.5, 2H), 1.81 (app d, J=13.5, 2h), 2.07 (s, 3H), 2.44–2.33 (m, 1H), 2.72–2.79 (m, 2H), 4.18–4.28 (br s, 2H), 5.50 (s, 1H).

Provenance & Evidence