Expanded geographic distribution and dietary strategies of the earliest Oldowan hominins and Paranthropus

The oldest Oldowan tool sites, ca. 2.6 million years ago (Ma), have previously been confined to Ethiopia’s Afar Triangle. We describe sites at Nyayanga, Kenya, dated to 3.032-2.581 Ma, and expand this distribution by over 1300 km. Furthermore, we found two hippopotamid butchery sites associated with mosaic vegetation and a C4 grazer-dominated fauna. Tool flaking proficiency was comparable to younger Oldowan assemblages, but pounding activities were more common. Tool use-wear and bone damage indicate plant and animal tissue processing. Paranthropus sp. teeth, the first from southwestern Kenya, possessed carbon isotopic values indicative of a diet rich in C4 foods. We argue that the earliest Oldowan was more widespread than previously known, used to process diverse foods including megafauna, and associated with Paranthropus from its onset

NH2 as a directing group: from the unexpected cyclopalladation of aminoesters to the preparation of benzolactams by Pd(II)-catalyzed carbonylation of N-unprotected arylethylamines

An unusual NH2-directed Pd(II)-catalytic carbonylation of quaternary aromatic α-amino esters to yield benzolactams has been developed. The steric hindrance around the amino group is pivotal for the success of the process. The stoichiometric cyclometallation of a variety amino esters has been studied in order to evaluate the influence of the different variables (size of the metallacycle, aromatic ring substituents, and steric bulk) in the process, and a complete kinetico-mechanistic study of the cyclopalladation process has been carried out. The experimental results indicate that the full substitution of the carbon in the α position of the amino esters plays an important role in their cyclopalladation reaction. The reaction shows a strong bias to 6-membered lactams over the 5-membered analogues, which can be explained by a greater reactivity of the six-membered palladacycles