Methyl propiolate → 2-Hydroxy-7,8-dihydro-5(6H)-quinolinone

Temperature

102.5 °C

A mixture of 3-aminocyclohex-2-enone (5.00 g, 45.0 mmol) and methyl propiolate (5.00 mL, 59.8 mmol) was heated without stirring at 100-105° C. for 2 h. The reflux condenser was removed, and the brown, homogeneous reaction mixture was heated to 170° C. to remove any excess methyl propiolate. At ˜165° C., the product started to crystallize. The resulting dark brown solidified reaction mixture was triturated quickly with dichloromethane (2×5 mL)). The solid was then suspended in methanol and sonicated for 60 min., collected by vacuum filtration, washed with methanol, and dried to give 7,8-dihydroquinoline-2,5(1H,6H)-dione (1.49 g, 9.13 mmol, 20% yield) as a yellow solid. The compound had an HPLC ret. time=0.638 min. (condition A); LC/MS M+1=163.9. 1H NMR (500 MHz, DMSO-d6) δ ppm 1.99 (quin, J=6.38 Hz, 2H), 2.39-2.44 (m, 2H), 2.78 (t, J=6.24 Hz, 2H), 6.23 (d, J=9.43 Hz, 1H), 7.76 (d, J=9.43 Hz, 1H), and 12.07 (br. s., 1H).

1. temperaturewas heated
2. customThe reflux condenser was removed
3. temperaturethe brown, homogeneous reaction mixture was heated to 170° C.
4. customto remove any excess methyl propiolate
5. customAt ˜165° C.
6. customto crystallize
7. customThe resulting dark brown solidified reaction mixture was triturated quickly with dichloromethane (2×5 mL))
8. customsonicated for 60 min.
9. filtrationcollected by vacuum filtration
10. washwashed with methanol
11. customdried

ORD record

ord-92e3451f78054e9b9219e18df1eb1ede

Source dataset

uspto-grants-2015_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09216972B2