Diisopropylamine → methyl 4-(2-tert-butoxy-2-oxoethyl)tetrahydro-2H-pyran-4-carboxylate

Temperature

-35 °C

Step 2 Diisopropylamine (1.28 mL, 9.16 mmol) was diluted with tetrahydrofuran (2 mL) and cooled to −78° C. n-Butyllithium (2.5 M, 3.66 mL, 9.16 mmol) was added dropwise, and the solution was allowed to stir for 1 h. Methyl tetrahydro-2H-pyran-4-carboxylate (1.1 g, 7.63 mmol) was added as a solution in tetrahydrofuran (1.5 mL) at −78° C. The mixture was allowed to warm to −35° C. and stirred for 1 h. tert-Butyl bromoacetate (1.58 mL, 10.7 mmol) was added neat at −35° C. The mixture was allowed to warm to 0° C. and stirred for 2 h. The mixture was stirred at rt overnight. Water was added at 0° C. and the mixture extracted with ethyl acetate. The organic phase was washed with brine, and dried over sodium sulfate. The crude product was purified by flash chromatography (Biotage Flash 40M, 6:1 hexane/ethyl acetate) to afford methyl 4-(2-tert-butoxy-2-oxoethyl)tetrahydro-2H-pyran-4-carboxylate (1.12 g, 56%). LC-MS ret. time 2.47 min, m/z 258.7 (MH+); 1H NMR (300 MHz, CDCl3) δ 1.38 (s, 9H), 1.52-1.61 (m, 2H), 2.00-2.07 (m, 2H), 2.50 (s, 2H), 3.52-3.60 (m, 2H), 3.70 (s, 3H), 3.71-3.77 (m, 2H).

1. additionwas added dropwise
2. additionwas added neat at −35° C
3. temperatureto warm to 0° C.
4. stirringstirred for 2 h
5. stirringThe mixture was stirred at rt overnight
6. extractionthe mixture extracted with ethyl acetate
7. washThe organic phase was washed with brine
8. dry with materialdried over sodium sulfate
9. customThe crude product was purified by flash chromatography (Biotage Flash 40M, 6:1 hexane/ethyl acetate)

ORD record

ord-79e21ed2d97c4cf68a1ff555145741b6

Source dataset

uspto-grants-2008_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07423156B2