2,2-((Disulfanediylbis(methylene))bis(cyclopropane-1,1-diyl))bis(2-hydroxyacetic Acid) Diethyl Ester

2,2''-((Disulfanediylbis(methylene))bis(cyclopropane-1,1-diyl))bis(2-hydroxyacetic Acid) Diethyl Ester is an impurity formed in the synthesis of Montelukast (M568000), a selective leukotriene D4-receptor antagonist used as an antiasthmatic agent.