Pyridine → (4R,5R)-3-Acetylamino-4,5-dimethyl-(Z)-oct-2-enoic Acid Ethyl Ester

Participants

Reaction Conditions

Reaction Steps

To a 1 L 3-necked round bottom flask equipped with an overhead stirrer, thermocouple, addition funnel, and nitrogen inlet, was charged 150 g (0.70 mol) of (4R,5R)-3-amino-4,5-dimethyl-(Z)-oct-2-enoic acid ethyl ester and 50 mL of dry CH2Cl2. The reaction mixture was cooled to −20° C. To the mixture was added, successively, acetyl chloride (60 mL, 0.84 mol) and pyridine (66.8 g, 0.84 mol) over 0.5-hour time intervals. After the additions, the mixture was stirred at −20° C. to 0° C. for 2 hours and then filtered to remove the pyridine.HCl salt. The filtrate was diluted with 200 mL of CH2Cl2 and washed 2× with aliquots of aq NH4Cl. The organic solution was treated with silica gel (50 g), MgSO4 (20 g) and charcoal (20 g), and stirred at room temperature for 0.5 hours. The solids were filtered off and the filtrate was concentrated under reduced pressure to give 166.5 g (93% yield) of the titled compound as an oil: 1H NMR (400 MHz, CHLOROFORM-D) 0.85 (t, J=7.4 Hz, 3 H), 0.95 (d, J=6.8 Hz, 3 H), 1.00 (d, J=7.0 Hz, 3 H), 1.11 (m, 1 H) 1.29 (t, J=5.8 Hz, 3 H), 1.40–1.25 (m, 2 H), 1.65 (m, 1 H) 2.13 (s, 3 H), 3.80 (m, 1 H) 4.2–4.14 (m, 3 H), 5.01(s, 1 H), 11.28(s, 1 H).

Provenance & Evidence