Figure 1. Resolution of racemic mixture to synthesise GSK923295.

The desired (S)-enantiomer (2) was obtained by the resolution of the racemic mixture of 1-(2-amino-3-pyridinyl)ethanol (rac-2), through the reaction with S-ethyl thiohexanoate at 39°C with Candida Antarctica Lipase B enzyme (50% w/w). The pure enantiomer (2) and the intermediate (1) then reacted to give the pyridyl imidazole (5), with subsequent reactions yielding GSK923295 (6).