Provided herein are compounds that are useful intermediates that may used to synthesize myeloid cell leukemia 1 protein (Mcl-1) inhibitors. Also provided are Mcl-1 inhibitors, methods of their preparation, related pharmaceutical compositions, and methods of using the same. For example, provided herein are compounds of Formula I, and pharmaceutically acceptable salts thereof and pharmaceutical compositions containing the compounds. The compounds and compositions provided herein may be used, for example, in the treatment of diseases or conditions, such as cancer.