The invention provides compounds of formula I and compositions thereof. The invention further provides methods of using the compounds and compositions. The compounds of the invention can provide high affinity binding to sigma-1 receptors in a mammal. The compounds can exhibit selectivity for the sigma-1 receptor over the sigma-2 receptor. The compounds and compositions of the invention can also be used to treat conditions that involve the sigma-1 receptor, such as addiction, cardiovascular conditions, and cancer, for example, cancer of the breast, lung, prostate, ovarian, colorectal, or the CNS.