[4] The first confirmed synthesis of cyclopropene, carried out by Dem'yanov and Doyarenko, involved the thermal decomposition of trimethylcyclopropylammonium hydroxide over platinized clay at approximately 300 °C.

Later Schlatter improved the pyrolytic reaction conditions using platinized asbestos as a catalyst at 320–330 °C and obtained cyclopropene in 45% yield.

[7] Allyl chloride undergoes dehydrohalogenation upon treatment with the base sodium amide at 80 °C to produce cyclopropene in about 10% yield.

Adding allyl chloride to sodium bis(trimethylsilyl)amide in boiling toluene over a period of 45–60 minutes produces the targeted compound in about 40% yield with an improvement in purity:[9] 1-Methylcyclopropene is synthesized similarly but at room temperature from methallylchloride using phenyllithium as the base:[10] Treatment of nitrocyclopropanes with sodium methoxide eliminates the nitrite, giving the respective cyclopropene derivative.

The mechanism is assumed to be a free-radical chain reaction, and the product, based on NMR spectra, is thought to be polycyclopropane.