Diisopropylamine → 3-(4-Propylbenzoyl)-7-vinylchroman-4-one

Participants

Reaction Conditions

Reaction Steps

To a flame-dried 10 mL round-bottom flask under nitrogen charged with butyllithium (2.5 M in hexanes) (0.875 mL, 2.19 mmol) in THF (1 mL) at 0° C. was added diisopropylamine (0.312 mL, 2.19 mmol) dropwise. The solution was stirred at 0° C. for 20 min. The solution was then cooled to −78° C., and 7-vinylchroman-4-one (Preparation 2D, 1.79 M in THF) (1.02 mL, 1.82 mmol) was added dropwise via syringe. The mixture was stirred for 20 min. at −78° C. 4-propylbenzoyl fluoride (0.303 g, 1.823 mmol) in 1 mL of THF was then added dropwise via syringe, and the reaction mixture was stirred at −78° C. for 60 min. and then warmed to room temperature. The reaction was quenched with 1N aqueous hydrochloric acid (5 mL) and extracted with ethyl acetate (3×20 mL). The organic layer was washed with brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The yellow residue was purified by flash silica gel chromatography using a mixture of ethyl acetate in hexane (5%-12%) to give 3-(4-propylbenzoyl)-7-vinylchroman-4-one (0.179 g, 0.559 mmol, 31% yield). The compound was triturated with methanol with sonication, filtered, washed with methanol, and dried to give 3-(4-propylbenzoyl)-7-vinylchroman-4-one (0.125 g, 0.390 mmol, 21% yield) as a yellow solid. LC/MS M+1=321.2. 1H NMR (500 MHz, DMSO-d6) δ ppm 0.91 (t, 3H), 1.58-1.68 (m, J=7.42, 7.42, 7.42, 7.42, 7.21 Hz, 2H), 2.65 (t, J=7.63 Hz, 2H) 4.71-4.77 (m, 1H), 4.78-4.83 (m, 1H), 5.20 (dd, J=9.16, 4.99 Hz, 1H), 5.47 (d, J=11.10 Hz, 1H), 6.05 (d, J=17.76 Hz, 1H), 6.73-6.82 (m, 1H), 7.17 (s, 1H) 7.24 (dd, J=8.18, 1.25 Hz, 1H), 7.38 (d, J=8.32 Hz, 2H), 7.73 (d, J=8.05 Hz, 1H), and 7.96 (d, J=8.32 Hz, 2H).

Provenance & Evidence