A General, Diastereoselective Synthesis of Highly Functionalized Bicyclo[n.3.1]alkane Systems Based on an Anionic Domino Reaction of alpha-Nitrocycloalkanones
Résumé
The base-promoted Michael-aldol anionic domino reactions of cyclic α-nitro ketones and α,β-unsaturated aldehydes af- forded bicyclo[n.3.1]alkanone systems of seven different ring sizes (n = 3-9), normally in excellent yields. This can be considered the first general method for the synthesis of this type of carbocycle. Furthermore, up to four stereocentres are generated, three of which are contiguous and include a functionalized quaternary bridgehead carbon atom. The diastereo- selectivity was often complete, was much higher than in less general reactions based on related domino processes, and involved the generation of a different major diastereomer due to the control of the Michael and aldol individual steps of the reaction by the nitro group.