(–)-Curvulamine

When you’re looking at a target or drawing out intermediates in a synthesis, certain functional groups just make your heart sink. They might bind to transition metals, be reactive when you don’t want them to be, complicate purification – or sometimes all of the above. Amusingly, medicinal chemists have a term-of-art for these kinds of red-flag functionalities: Pains (from Pan-Assay Interference compounds). The term originates in a seminal 2010 paper that listed functional groups known to confuse high-throughput screens, so researchers could avoid these Pains in the ass(ay).