Housane or bicyclo[2.1.0]pentane is a saturated cycloalkane with the formula C5H8. It is a colorless, volatile liquid at room temperature. It was named "housane" because of its shape, which resembles a simple drawing of a house. Structurally, the molecule consists of cyclopropane fused to cyclobutane. The synthesis of molecules containing multiple strained rings, such as housane, is a traditional endeavor in synthetic organic chemistry.

Preparation

The first synthesis of housane was reported by Criegee in 1957, where housane was obtained from the pyrolysis of 2,3-diazabicyclo[2.2.1]hept-2-ene. Housane can be prepared in several steps starting with cyclopentadiene. Other methods include photolysis of 2,3-diazabicyclo[2.2.1]hept-2-ene, pyrolysis of N-Phenyl-2-oxo-3-azabicyclo[2.2.1]heptane, and addition of methylene to cyclobutene.

Structure and properties

Housane is easily attacked by bromine or iodine. In the presence of a platinum catalyst at room temperature, it is hydrogenated into cyclopentane. Reaction with hydrogen bromide at lower temperatures affords bromocyclopentane. Housane also reacts with lead tetraacetate, forming cis-1,3-diacetoxycyclopentane among other products. Housane is thermally quite stable, isomerizing to cyclopentene at 330 °C.