Divergent Cascade Ring‐Expansion Reactions of Acryloyl Imides.

Macrocyclic and medium‐sized ring ketones, lactones and lactams can all be made from common acryloyl imide starting materials through divergent, one‐pot cascade ring‐expansion reactions. Following either conjugate addition with an amine or nitromethane, or osmium(VIII)‐catalysed dihydoxylation, rearrangement through a four‐atom ring expansion takes place spontaneously to form the ring expanded products. A second ring expansion can also be performed following a second iteration of imide formation and alkene functionalisation/ring expansion. In the dihydroxylation series, three‐ or four‐atom ring expansion can be performed selectively, depending on whether the reaction is under kinetic or thermodynamic control. [ABSTRACT FROM AUTHOR]