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

Participants

Reaction Conditions

Reaction Steps

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).

Provenance & Evidence