Double Addition of Grignard Reagents to N-Glycosyl Nitrones: a New Tool for the Construction of Enantiopure Azaheterocycles

C-Pheynl-N-erythrosylnitrone 3 behaves as a C1,C1' bis-electrophile, undergoing a double addition of Grignard reagents in a domino fashion to afford acyclic hydroxylamines 4. The reaction proceeds at 0 degreesC with variable degrees of diastereoselectivity, from moderate to good. mainly depending on the organomagnesium reagent used. The usefulness of compounds 4 has been exemplified with the synthesis of pyrroloazepine 12 through a ring closing metathesis key step