Nouvelle voie d'acces aux β-nitroenones premiere preparation de β-nitroenones acycliques
摘要:
We describe here a new and mild method of synthesis of acyclic beta-nitroenones. Nitroepoxydes IVunderbar, prepared by epoxydation of the allylic nitroolefins IIIunderbar, react with silicagel or aluminium isopropoxide according to the substrate, to give the nitroethylenic alcohols Vunderbar. Their oxydation by PCC under sonication leads to the beta-nitroenones VIunderbar.
Stereoselectivity of the reaction of acyclic ketone enolates with (E)-β-nitroenones was investigated according to the nature of the base used to accomplish deprotonation. The stereoselectivity and the regioselectivity of the reaction of ketone enolates with (E)-β-nitroenones could be enhanced by the use of trichlorotitanium enolates, which allowed the formation of diastereomeric mixture of (E)-3-h