Hydrochloric Acid → 3,4-dihydro-2H-pyrano[2,3-c]pyridin-6-ylmethanol

Temperature

45 °C

To a vessel was added with stirring methyl 3,4-dihydro-2H-pyrano[2,3-c]pyridine-6-carboxylate (7.4 g, 1 eq) and tetrahydrofuran (THF) (32 mL). The mixture was heated to 55° C. whereupon 2M LiBH4 in THF solution (20 mL, 1.05 eq.) was added over 1 h. The stirring continued at 55° C. until reduction was complete at which point the mixture was cooled to 45° C. and 6N HCl (37 mL) was carefully added to the mixture. The stirring was continued for 1 h then the mixture was cooled to 25° C. The pH was adjusted to ˜9.5 to 10 with 50 wt % aqueous NaOH solution. The organics were extracted with 2-methyltetrahydrofuran (2×37 mL). The combined organic layers were concentrated under reduced pressure and crystallized to provide (3,4-dihydro-2H-pyrano[2,3-c]pyridin-6-yl)methanol as an off-white solid. 1H NMR (300 MHz, CDCl3) δ ppm 8.10 (s, 1H), 6.91-6.99 (m, 1H), 4.65 (s, 2H), 4.18-4.29 (m, 2H), 3.42 (s, 1H), 2.79 (t, J=6.50 Hz, 2H), 1.96-2.12 (m, 2H); 13C NMR (75 MHz, CDCl3) δ ppm 151.09, 150.39, 137.87, 131.40, 121.14, 66.51, 64.10, 24.22, 21.55; HRMS (M+H) m/z, calcd for C9H12NO2, 166.0868; found, 166.0861.

1. additionwas added over 1 h
2. customcontinued at 55° C. until reduction
3. temperaturethe mixture was cooled to 25° C
4. extractionThe organics were extracted with 2-methyltetrahydrofuran (2×37 mL)
5. concentrationThe combined organic layers were concentrated under reduced pressure
6. customcrystallized

ORD record

ord-91cc1c72daa948b1b93d5aa6b41f9ac9

Source dataset

uspto-grants-2014_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08759523B2