Methylene shuffle

A methylene shuffle is a technique used in medicinal chemistry to to modify the hydrophobicity of a chemical compound. In drug design, the solubility and membrane permeability of a molecule can be complicated due to its polarity. If a molecule is not sufficiently polar, its alkyl groups can be replaced with smaller alkyl groups or by removing alkyl groups entirely. Sometimes there is a benefit in increasing the size of one alkyl group and decreasing the size of another, a shuffling of the methylene groups.