Hydrochloric Acid → Tert-butyl 4-acetamido-4-(tert-butylcarbamoyl)oct-7-enylcarbamate

Participants

Reaction Steps

A solution of tert-butyl 4-oxooct-7-enylcarbamate (Example 159, 2.17 g, 8.99 mmol) and ammonium acetate (4.16 g, 53.9 mmol) in 2,2,2-trifluoroethanol (7 mL) was treated with tert-butyl isocyanide (4.1 mL, 35.9 mmol) and stirred at room temperature for 3 days. Ethyl acetate (15 mL) and 2 M aq HCl (10 mL) were added and the solution was vigorously stirred for an additional 3 hrs. The phases were separated and the organic phase was washed successively with water and sat'd aq sodium chloride, dried over MgSO4, filtered and concentrated. The crude viscous yellow residue was purified by flash column chromatography (5-50% ethyl acetate in hexanes) to give tert-butyl 4-acetamido-4-(tert-butylcarbamoyl)oct-7-enylcarbamate (2.27 g, 66%). 1H NMR (CDCl3, 500 MHz) δ 6.97 (s, 1H), 5.79-5.70 (m, 1H), 5.56 (s, 1H), 4.99-4.92 (m, 2H), 4.55 (bs, 1H), 3.08-3.06 (m, 2H), 2.78-2.67 (m, 2H), 2.03-1.93 (m, 1H), 1.99 (s, 3H), 1.84-1.76 (m, 1H), 1.42 (s, 9H), 1.38-1.34 (m, 2H), 1.36 (s, 9H), 1.29-1.24 (m, 2H), ESI MS found for C20H37N3O4 m/z [406.5 (M+Na+), 384.6 (M+1), 382.5 (M−1)].

Provenance & Evidence