Cyclopropylacetylene

synthetischeCyclopropylacetylene was prepared in a two-step procedure by dichlorination of cyclopropyl methyl ketone with phosphorus pentachloride (PCl5) followed by double dehydrohalogenation with a strong base. This sequence presented significant scale-up problems with low overall yields (20-25%). Similarly, cyclopropylacetylene has been prepared by base-induced dehydrohalogenation of bromovinylcyclopropane . Cyclopropylacetylene has also been prepared from the 1-trimethylsilyl derivative of cyclopropylacetylene, which was prepared by treatment of 5-chloro-1-trimethylsilyl-1-pentyne with lithium diisopropylamide at 78°C followed by warming to room temperature.