Acetaldehyde → HCID 68723789, compound

Participants

Reaction Conditions

Reaction Steps

At −78° C. under N2, a solution of diisopropylamine (0.53 ml, 3.72 mmol) in anhydrous THF (2.75 ml) was treated dropwise with a solution of 1.6M n-BuLi in hexane (2.33 ml, 2.75 mmol). The resulting solution was warmed to −10° C., cooled to −78° C., and treated dropwise with a solution of 1-(5-methylspiro[2.5]oct-5-en-4-yl)ethanone (470 mg, 2.87 mmol) in anhydrous THF (2.75 ml). The resulting solution was warmed to −20° C., cooled to −78° C. and treated with a solution of acetaldehyde (0.81 ml, 14.3 mmol) in anhydrous THF (2.75 ml). The resulting solution was warmed to −10° C., cooled to −78° C., and treated slowly with a mixture of 2N HCl (6 ml) and of a saturated aqueous solution of NaCl (3.6 ml). The mixture was then warmed to 0° C., the aqueous phase extracted three times with Et2O and the combined organic phases washed with a saturated aqueous solution of NaHCO3, a saturated aqueous solution of NH4Cl, a saturated aqueous solution of NaCl, dried (Na2SO4), and concentrated. The residue (596 mg) was dissolved in toluene (20 ml) and treated with para-toluene sulfonic acid monohydrate (27 mg, 0.143 mmol). The resulting solution was stirred at 80° C. for 3 h, cooled, and poured into a saturated aqueous solution of NaHCO3. The aqueous phase was extracted three times with Et2O and the combined organic phases washed with a saturated aqueous solution of NH4Cl, a saturated aqueous solution of NaCl, and concentrated. FC (200 g SiO2, hexane/Et2O 10:0.5) of the crude product (730 mg) gave (E)-1-(5-Methylspiro[2.5]oct-5-en-4-yl)but-2-en-1-one (0.354 g, 64%, 2 steps). Boiling point: 50° C. (0.07 mbar).

Provenance & Evidence