Dihydrooxazine Oxides as Key Intermediates in Organocatalytic Michael Additions of Aldehydes to Nitroalkenes


  • We thank Esa Haapaniemi and Mirja Lahtiperä for assistance with the NMR and HRMS measurements, respectively. This work was supported by the Academy of Finland (project Nos. 123813 and 138854 to P.M.P.), the Hungarian Research Foundation (OTKA, Grant NN-82955), and COST CM0905. A.V. thanks Academy Prof. Kari Rissanen for funding through the Academy of Finland (KR project Nos. 130629, 122350, and 140718).


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Pause and play: Dihydrooxazine oxides are stable intermediates that are protonated directly, without the intermediacy of the zwitterions, in organocatalytic Michael additions of aldehydes and nitroalkenes (see scheme, R=alkyl). Protonation of these species explains both the role of the acid co-catalyst in these reactions, and the observed stereochemistry when the reaction is conducted with α-alkylnitroalkenes.