Ammonium Chloride → HCID 86751639, compound

Participants

Reaction Steps

A solution, cooled to -78°, of 1.78 ml (10 mmol) of (2R)-(-)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine in 5 ml of absolute tetrahydrofuran is treated dropwise with 6.8 ml (11 mmol) of a solution of butyllithium in hexane. The reaction solution is left at -78° for 1 hour and at -20° for 1 hour and then again cooled to -78°. Subsequently, a solution of 1.75 g (10 mmol) of (S)-1-(bromomethyl)-3-cyclohexene in 5 ml of absolute tetrahydrofuran is added. After 2 hours at room temperature the solution is again cooled to -10°, treated with 5 ml of saturated ammonium chloride solution and extracted with ether. The organic phase is washed with water, dried over sodium sulphate and evaporated under reduced pressure. For purification, the residue is chromatographed twice on silica gel using a 9:1 mixture of toluene and ethyl acetate as the eluent. (2S,5R)-2-[(S)-3-Cyclohexen-1-ylmethyl]-2,5-dihydro-5-isopropyl-3,6-dimethoxypyrazine is obtained as a colourless oil; MS: 278 (M)+.

Provenance & Evidence