2-Naphthalenecarboxaldehyde → 1-(2-Naphthyl)-6-heptenol

Participants

Reaction Steps

A flame-dried round-bottomed flask was charged with magnesium turnings (1.23 g, 50.75 mmol) and stirred under vacuum for 15 minutes and then applied under nitrogen atmosphere. THF (70 mL) was added followed by 1,2-dibromoethane (381 mg, 2.03 mmol), and the mixture was brought to the boiling point for 1 minute, then and cooled down to room temperature. A solution of 6-bromohexene (8.28 g, 50.75 mmol) in THF (30 mL) was transferred via cannula to the magnesium flask and the mixture was refluxed overnight and cooled to −78° C. A solution of 2-naphthaldehyde (6.10 g, 39.04 mmol) in THF (30 mL) was transferred via cannula to the Grignard reagent and the mixture was slowly warmed to 0° C. over 3 hours and kept at that temperature for 2 hours. The reaction was quenched with a saturated aqueous ammonium chloride solution and THF was evaporated in vacuo. The aqueous residue was poured into a separating funnel containing water and the compound was extracted with diethyl ether (2×100 mL). The combined organic layers were washed with brine, dried over magnesium sulfate and concentrated. The residue was purified by flash chromatography (10% to 15% ethyl acetate in hexane), affording the title compound 181 in 89% yield (8.33g). 1H NMR: (300 MHz, CDCl3) δ: 7.85-7.78 (m, 4H), 7.51-7.44 (m, 3H), 5.85-5.72 (m, 1H), 5.02-4.91 (m, 2H), 4.87-4.82 (m, 2H), 2.08-2.01 (m, 2H), 1.94-1.80 (m, 2H), 1.53-1.23(m, 4H). MS (ESI)=223 (MH+—H2O).

Provenance & Evidence