2-Chloro-5-iodopyrazine

2-Chloro-5-iodopyrazine is a pharmaceutical intermediate that has been reported in the literature to be used in the preparation of estrogen receptor covalent antagonists and orexin receptor modulators.

2-Chloro-5-iodopyrazine can be used to prepare tetrasubstituted olefin compounds having the following structure. These compounds are estrogen receptor covalent antagonists. These compounds can be used to inhibit the growth of cell cultures of MCF7ER-alpha (wild-type) and MCF7ER-alpha (Y537S mutant) cells. Other compounds known to inhibit the growth of cell cultures of MCF7ER-alpha (wild-type) cells (e.g., tamoxifen, raloxifene, and fulvestrant) are currently used to treat breast cancer in human patients. Therefore, the compounds disclosed herein can be used to treat breast cancer expressing ER-alpha in human patients, and specifically, to treat breast cancer expressing Y537S mutant ER-alpha in human patients.