Synthesis of glycosidase-inhibiting iminopolyols by Cope-House cyclization of unsaturated hydroxylamines.: III.: Pyrrolidine N-oxides by stereoselective addition of Grignard and lithium compounds to 4,5-dideoxy-2,3-O-isopropylidene-D-erythro-4-pentenose N-benzyl nitrone and subsequent Cope-House cyclization

The addition of Grignard reagents to D-erythro-4-pentenose N-benzyl nitrone 5, which is easily accessible from D-ribose, furnishes omega -unsaturated hydroxylamines that readily undergo Cope-House cyclization to afford pyrrolidine N-oxides, The stereoselectivity of the addition step is altered by either employing organolithium compounds or Lewis acids as complexing agents, The pyrrolidine N-oxides obtained by this sequence serve as key intermediates in the synthesis of 2,5-disubstituted pyrrolidine-3,4-diols (to be discussed in detail separately), both constituting new potential inhibitors of glycosidases.