Product Application: 2-Chloro-1-(6-methoxy-1,2,3,4-tetrahydroquinolin-1-yl)ethan-1-one is a cysteine-reactive small-molecule fragment for chemoproteomic and ligandability studies for both traditionally druggable proteins as well as "undruggable," or difficult-to-target, proteins. This fragment electrophile, or "scout" fragment, can be used alone in fragment-based covalent ligand discovery or incorporated into bifunctional tools such as electrophilic PROTAC molecules for targeted protein degradation as demonstrated by the Cravatt Lab Lab for E3 ligase discovery.