Bicyclobutane

Bicyclobutane is an organic compound with the formula C4H6. It is a bicyclic molecule consisting of two cis-fused cyclopropane rings, and is a colorless and easily condensed gas. Bicyclobutane is noted for being one of the most strained compounds that is isolatable on a large scale – its strain energy is estimated at 63.9 kcal mol−1. It is a nonplanar molecule, with a dihedral angle between the two cyclopropane rings of 123°.Multiple research groups have reported success in synthesizing bicyclobutane-containing molecules using enzymes in living cells. One group reported the transformation of linolenic acid into a bicyclobutane fatty acid via a protein produced by a strain of the cyanobacterium Anabaena sp. (strain PCC 7120). The other group reported a directed evolution approach, whereby engineered heme protein was expressed in E. coli and successfully optimized for increased rate and yield of biosynthesis of a substituted bicyclobutane derivative.