Thianthrenation is a useful strategy for the late-stage diversification of complex small molecules owing to the positional selectivity and the synthetic versatility of thianthrenium salts as electrophilic linchpins. However, substrate-dependent identification of suitable reaction conditions for thianthrenation can be difficult. Reported reaction conditions for the functionalization of thianthrenium salts vary significantly and, in some instances, lack robustness and practicality. Herein, we report a generalized approach for the preparation of thianthrenium salts and two reaction manifolds for practical, robust, and parallel diversification of thianthrenium salts.