The theoretical basis of FBDD is to select favorable fragment combinations or extensions to obtain new drug molecules, with a higher probability of obtaining highly active drug candidates. Compared with the screening of millions of macromolecules, thousands of fragment molecules can be combined to form millions of drug structures, which are easier to collect and manage. In addition, fragments have smaller molecular weights, relatively higher solubility, and easier structural optimization. The potential of over-the-counter medicine is higher. Targeted covalent inhibitors and chemical probes have become part of drug discovery methods. Given the advantages of fragment-based drug discovery, screening electrophilic fragments has become a promising alternative to discover and verify new targets and generate viable chemical starting points, even for targets that are almost difficult to handle. In response to this situation, we designed a small library of heterocyclic electrophilic compounds. General technology for covalent fragment screening ：