IX Pregabalin Lyrica is an anticonvulsant drug used to treat

IX. Pregabalin (Lyrica) is an anticonvulsant drug used to treat fibromyalgia. Clinical studies have found that only the (S) enantiomer of pregabalin is biologically active. A conceivable synthetic route to making (S)-pregabalin would involve conversion of chiral alcohol A to chiral nitrile B shown below. Propose a synthetic route from alcohol A to nitrile B using NaCN as your only other source of carbon that would provide the correct (S) stereochemistry. (8 pts) 4 min OMe OH OH O CN O H2N pregabalin

Solution

The best reagent is NaCN.

Explanation; cyanide ion is a strong nucleophile which gives SN2 substitution reaction with alcohol. cyanide ion attacks the carbon atom bearing -OH group and eliminates leaving group to produce the product.