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While under a nitrogen atmosphere, a solution of tert-butyl 3-(methoxy(methyl)carbamoyl)-8-azabicyclo[3.2.1]octane-8-carboxylate (1.7 g, 5.7 mmol), in tetrahydrofuran (25 mL) was cooled to 0° C. and treated with 3-butenylmagnesiun bromide (0.5 M in THF, 28.5 mL, 14.3 mmol) in a drop wise manner. The solution was stirred for 1 hour at 0° C. then allowed to warm to room temperature overnight. The resulting solution was poured into water, acidified to pH 3-4 with 1 N hydrochloric acid, and extracted with ethyl acetate (3×). The combined organic phase was washed with saturated aqueous sodium chloride, dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. Purification by flash column chromatography (silica gel, 0-25% ethyl acetate in heptane) gave (1R,5S)-tert-Butyl-3-pent-4-enoyl-8-azabicyclo[3.2.1]-octane-8-carboxylic acid as a colorless oil (1.45 g, 87%); 1H NMR (CDCl3, 400 MHz) δ 5.81 (m, 1H), 5.01 (m, 2H), 4.29 (br s, 2H), 2.83 (m, 1H), 2.53 (t, J=7.5 Hz, 1H), 2.32 (q, J=7 Hz, 2H), 2.03 (m, 2H), 1.83 (t, J=12.5 Hz, 2H), 1.60-1.71 (m, 5H) and 1.48 (s, 9H); m/z for C17H27NO3 expected 293.2. found 316.3 (M+Na)+, 294.3 (M+H)+.

1. temperatureto warm to room temperature overnight
2. extractionextracted with ethyl acetate (3×)
3. washThe combined organic phase was washed with saturated aqueous sodium chloride
4. dry with materialdried over anhydrous magnesium sulfate
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customPurification by flash column chromatography (silica gel, 0-25% ethyl acetate in heptane)