Triphenylphosphine → Bromine triphenylphosphine

Participants

Reaction Steps

A solution of 2.6 g of triphenylphosphine in 30 ml of methylene chloride was treated dropwise at 0° C. with a solution of 0.519 ml of bromine in 20 ml of methylene chloride until a slight yellow colour persisted. The yellow suspension obtained was cautiously concentrated to dryness on a rotary evaporator and the yellowish, crystalline residue was dried in a high vacuum (0.5 Torr) at room temperature for 1 hour. The triphenylphosphine-bromine obtained was suspended in 50 ml of toluene and the suspension was concentrated to dryness on a rotary evaporator. Thereafter, the residue was suspended in 30 ml of toluene, the suspension was treated with a solution of 2.2 g of p-[trans-4-(2,3-epoxypentyl)cyclohexyl]benzonitrile in 10 ml of toluene and the mixture was stirred for 2 hours at 80° C. bath temperature. Low-pressure chromatography (0.5 bar) of the cooled reaction mixture on silica gel with toluene gave 2.83 g (84%) of p-[trans-4-(2,3-dibromopentyl)cyclohexyl]benzonitrile as a yellowish oil (containing 66.6% erythro form and 32.8% threo form); Rf-value (ethyl acetate/petroleum ether vol. 10:90) 0.33. This material was processed without additional purification.

Provenance & Evidence