Phosphorus tribromide → 1-Bromo-6,6-dimethylhept-2-en-4-yne

Participants

Reaction Steps

50 ml 48% HBr and 10 g PBr3 are stirred to homogeneity at 40°. An alcoholic solution of 13.5 g of 6,6-dimethyl-hept-1-en-4-yn-3-ol is then added dropwise at 10° and the resulting mixture stirred at room temperature for 11/2 hours. The reaction mixture is poured onto ice-water and repeatedly extracted with hexane. The organic phase is separated, washed repeatedly with aqueous NaCl, dried and concentrated on a rotary evaporator. NMR spectroscopy reveals that the resulting oily reaction product comprises a 3:1 mixture of trans- and cis-1-bromo-6,6-dimethyl-hept-2-en-4-yne which is employed directly in further alkylation.

Provenance & Evidence