Hydrochloric Acid → 3-(Quinolin-6-yl)prop-2-enal

Participants

Reaction Steps

A mixture of 6-quinolinecarboxaldehyde (1.58 g, 10.05 mmol, prepared as described in U.S. Pat. No. 5,559,256), (1,3-dioxolan-2-ylmethyl)triphenylphosphonium bromide (6.45 g, 15.02 mmol), and TDA-1 (3.20 mL, 10.00 mmol) in dichloromethane (50 mL) and sat. aq. K2CO3 (50 mL) was heated to reflux for 5 h. The layers were separated and the aqueous layer was extracted with dichloromethane (2×25 mL). The combined organic layers were washed with water (50 mL) and brine (50 mL), dried (MgSO4), and concentrated. THF (25 mL) and 10% HCl (25 mL) were added and the mixture was stirred for 1 h at rt. The reaction mixture was cooled to 0° C., made basic with 10% NaOH, and extracted with ethyl acetate (3×25 mL). The combined organic layers were washed with water (50 mL) and brine (50 mL), dried (MgSO4), and concentrated. Chromatography (SiO2, 1:1 hexane/ethyl acetate+0.2% triethylamine) provided a yellow solid that was partioned between ethyl acetate (20 mL) and 10% HCl (15 mL). The aqueous layer was washed with ethyl acetate (2×20 mL) and then made basic with 10% NaOH. The precipitated solids were collected by filtration, washed with water, and dried in vacuo to give 1.20 g (65%) of the title compound as a light yellow solid. MS 184 (M+H)+.

Provenance & Evidence