6-Chloro-4-[(2,2,3,3-d4-cyclopropylethynyl)trifluoromethylhydroxymethyl]-3H-benzoxazol-2-one

6-Chloro-4-[(2,2,3,3-d4-cyclopropylethynyl)trifluoromethylhydroxymethyl]-3H-benzoxazol-2-one, also known as "CP-690,550-d4", is a chemical compound that has been used in various research studies related to rheumatoid arthritis and other autoimmune diseases. The chemical structure of CP-690,550-d4 includes a benzoxazolone ring with a trifluoromethyl group attached to it. The molecule also contains a chloro group and a hydroxymethyl group, which contribute to its unique properties. The cyclopropylethynyl group is a deuterium-labeled version of the original molecule, which is used as a reference standard for isotopic labeling studies. CP-690,550-d4 is a potent inhibitor of JAK3 (Janus kinase 3), an enzyme that plays a crucial role in the immune system. By inhibiting JAK3, CP-690,550-d4 can prevent the activation of T-cells and other immune cells that contribute to the development of autoimmune diseases. CP-690,550-d4 has been studied for its potential to treat rheumatoid arthritis, psoriasis, and other autoimmune disorders. It has also been investigated as a potential therapy for organ transplantation rejection and certain types of cancer. Overall, CP-690,550-d4 is a valuable tool for researchers in the field of immunology and autoimmune diseases, and its unique chemical properties make it a useful reference standard for isotopic labeling studies.