Triethylamine → 3-Butyl-6-methyl-1,4-dioxane-2,5-dione

Temperature

60 °C

2.5 g 2-hydroxyhexanoic acid (18.9 mmol) and 2.1 mL 2-bromopropionyl bromide (19.7 mmol) were stirred at 75° C. under nitrogen for 12 h. 150 mL acetone and 5.3 mL anhydrous triethylamine (38 mmol) were added to the mixture and the solution was stirred for 3 h at 60° C. After filtration of the triethylammonium bromide salts, acetone was distilled off and the resulting mixture was dissolved in 300 mL ethyl acetate:hexane mixture (1:2). After filtration over silica gel the solvents were distilled off, and the remaining crude product was recrystallized from hexane. 1H NMR (500 MHz, CDCl3): δ 5.05 (q, 1H), 4.90 (dd, 1H), 1.9-2.15 (br m, 2H), 1.68 (d), 1.65 (d), (3H, of 2 diastereoisomers), 1.3-1.6 (br m, 4H), 0.93 (t, 3H). 13C NMR (500 MHz, CDCl3): δ 167.54, 166.93, 166.25, 165.85, 75.79, 72.50, 72.24, 31.61, 29.70, 26.69, 26.42, 22.19, 21.97, 17.52, 15.81, 13.72, 13.66. ELEM. ANAL. Calcd. for C9H14O4: C, 58.06; H, 7.53. Found: C, 57.62; H, 7.60. Yield: 40%.

1. filtrationAfter filtration of the triethylammonium bromide salts, acetone
2. distillationwas distilled off
3. dissolutionthe resulting mixture was dissolved in 300 mL ethyl acetate
4. filtrationAfter filtration over silica gel the solvents
5. distillationwere distilled off
6. customthe remaining crude product was recrystallized from hexane

ORD record

ord-6605662058434b14a0c1acdfcd9c8b92

Source dataset

uspto-grants-2016_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09375482B2