A highly efficient concept for the stereoselective synthesis of axially chiral biaryl target molecules is presented: the atroposelective ring cleavage of configurationally unstable lactone-bridged biaryls. The method has almost no restrictions concerning the substitution pattern, works even for substrates with high steric hindrance at the ortho-position(s) of the axis, and allows the optional, atropo-divergent preparation of each atropisomer from the same biaryl lactone precursor and a recycling of the undesired minor product in the sense of a chiral economy. A brpad series of successful application in natural product and ligand syntheses underlines the high value of the method.