Hydroxynitrile lyases (HNLs) catalyze the stereoselective formation of CÀC bonds between HCN and aldehydes or ketones yielding chiral cyanohydrins, which are versatile building blocks for the pharmaceutical and agrochemical industries.[1] Among the most important cyanohdrins are chiral a-hydroxy acids such as substituted mandelic acids,[1e, f, 2a] m- phenoxybenzaldehyde derivatives,[2c] and structures with additional aliphatic linkers ...