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Diels-Alder Reaction of Nitroolefins
H. Sundén, R. Rios, Y. Xu, L. Eriksson, A. Córdova*
Stockholm University, Sweden
23 January 2008 (online)
The diastereoselective and enantioselective formation of bicyclic Diels-Alder products 4 starting from α,β-unsaturated cyclic ketones 1 of different ring sizes and (hetero)aromatic nitroolefins 2 is described. Aliphatic nitroolefins give only traces of product. Commercially available, chiral diamine 3 in combination with DNBSA was used as catalyst. In accordance with the observed absolute stereochemistry, the reaction is suggested to proceed via a stepwise domino double Michael addition pathway. Alternatively, a concerted Diels-Alder mechanism may be considered.