Cover Picture

Ferenc Molnar, Gerrit A. Luinstra, Markus Allmendinger, andBernhard Rieger

The cover picture shows the molecular structure of the complex formed by Al(O-iPr)3(acts as Lewis acid), �-propiolactone, and the [Co(CO)4]� anion (aluminium: pink;carbon: grey; cobalt: blue; hydrogen: white; oxygen: red). This structure corresponds tothe product complex in the formation of �-lactones from epoxides and carbonmonoxide (schematically shown in the upper right hand corner). Carbonylation ofepoxides by using a combination of Lewis acids and cobalt carbonyls was studied bothby theoretical and experimental methods. Only the concerted interaction of a Lewisacid and a nucleophile (multisite catalysis) opens a low-energy pathway for transopening of oxirane rings. For more details see the article by F. Molnar, B. Rieger et al.on p. 1273 ff.