Cover Picture (Angew. Chem. Int. Ed. Engl. 11/1991)

The cover picture shows a supramolecular compound composed of a boroncontaining crown ether as the host and two guests, benzylamine and methanol. This graphic representation based on the data from an X‐ray structure was generated by the Insight‐II program. To illustrate the host–guest relationship better the two guests are represented as ball‐and‐stick models with their van der Waals surfaces depicted as violet nets (boron, green; oxygen, red; carbon, white; hydrogen, blue). The coordination of nucleophilic and electrophilic centers in one host molecule make it feasible to simultaneously bind guests of different reactivities, for example a substrate and a reagent. The realization of an important goal in supramolecular chemistry, the imitation of biocatalysts using much simpler chemistry, is now closer. Further details are reported by M. Reetz et al. on p. 1412 and 1474. The current boom in supramolecular chemistry is also documented in the review by S. Schneider (p. 1417) as well as in a number of communications including those from H. Reuter (p. 1482), Y. Kobuke et al. (p. 1496), F. Hawthorne et al. (p. 1507), and A. F. Williams et al. (p. 1490) in this issue.