Used primarily in organic synthesis as a chiral auxiliary, (S)-4-Phenyloxazolidine-2-thione helps in the stereoselective formation of carbon-carbon bonds. It is particularly valuable in asymmetric synthesis, enabling the production of enantiomerically pure compounds, which are crucial in the development of pharmaceuticals. Additionally, it serves as a building block in the synthesis of complex molecules, including natural products and active pharmaceutical ingredients. Its role in facilitating enantioselective reactions makes it a key component in the synthesis of drugs with specific chiral requirements, enhancing their efficacy and reducing side effects.