Copper-Catalyzed Aerobic Cyclization of β,γ-Unsaturated Hydrazones with Concomitant C═C Bond Cleavage

A Cu-catalyzed aerobic oxidative cyclization of β,γ-unsaturated hydrazones for the preparation of pyrazole derivatives has been developed. The hydrazonyl radical promoted the cyclization, along with a concomitant C═C bond cleavage of β,γ-unsaturated hydrazones. This process has been verified via several control experiments, including a radical-trapping study, an ¹⁸O-labeling method, and the identification of the possible byproducts. The advantages of this reaction include operational simplicity, a broad reaction scope, and a mild selective reaction process.

More Twins in the Scientific Literature of the 21st Century

This Essay highlights the complex issue of twinning in science publications. Historical accounts present cases where two scientists focused on the same problem and came up with the same solution following different paths. This has changed in the present day. The concurrent publication of rather similar research papers from different groups has increased in frequency since 2010. In the past, twinning in research publications was serendipitous, and there was a healthy competition among teams working on similar projects. Today, twinning has become more frequent. This can be attributed to the urge of researchers to have publications on popular topics, the tendency to base research programs on popular keywords, and funding agencies preferentially supporting certain areas of research. With vast amounts of literature being generated, editorial offices and referees may not be able to find these twins very easily. As we inch away from human ingenuity towards artificial intelligence, twinning may become even more frequent.