Ammonium Chloride → (S)-(-)-methyl 3-methyl-6-heptenoate

Participants

Reaction Conditions

Reaction Steps

To a suspension of 23.3 g (65.2 mmol) of methyltriphenylphosphonium bromide in 120 ml of dry THF is added 36.9 ml (58.7 mmol) of 1.59 N n-butyllithium-n-hexane solution dropwise under ice cooling in a nitrogen atmosphere. After additional stirring at the same temperature for 10 minutes, the mixture was cooled to -50° C., and a solution of 5.2 g of crude aldehyde 31 (prepared in 31-(2)) in 80 ml of dry THF is added dropwise thereto. Then, the mixture is stirred at the same temperature for 10 minutes, and warmed to room temperature over an hour. To the reaction mixture is added a saturated aqueous solution of ammonium chloride, and the mixture is extracted with ether twice. The extract is washed with water and a saturated aqueous solution of sodium chloride, dried over anhydrous mangeium sulfate, and evaporated at atmospheric pressure. To the residue is added 400 ml of n-pentane and the mixture is stirred under ice cooling for 30 minutes. The precipitated triphenylphosphinoxide is removed by filtration through 100 g of silica gel. The silica gel is washed with 500 ml of mixture of ether:n-pentane=1:9. The filtrate and washing are combined and concentrated at atmospheric pressure. The residue is distilled under reduced pressure to give 2.19 g of the desired olefin 32 as an oil in 43.1% yield from compound 30.

Provenance & Evidence