Cyclization of unsaturated hydroxylamine derivatives

The reverse Cope cyclisation: a classical reaction goes backwards

“…8 This serendipitous discovery was made during attempts to prepare the dioxime 19 from the corresponding 1,3-dione 18 under standard conditions (NH 2 OH·HCl, NaOAc, aq. dioxane, reflux).…”

“…This could then undergo reduction by the hydroxylamine 7 as suggested in Scheme 4. Thus, proton exchange, not unreasonable when one considers the relatively low pK a (13.7) of the hydroxyl group in hydroxylamine, 7,8 could generate the ammonium salt 11 accompanied by the oxide 12. This could then deoxygenate the salt 11, either directly, as shown, or by N-hydroperoxide formation and rearrangement, to give the observed amine 9, together with the intermediate 13; loss of water would then generate the reactive nitrone 14.…”

PyrrolidineN-Oxides by Stereoselective Addition of Grignard and Lithium Compounds to 4,5-Dideoxy-2,3-O-isopropylidene-D-erythro-4-pentenoseN-Benzyl Nitrone and Subsequent Cope−House Cyclization

“…This transformation was discovered in 1976 by House and co-workers and was originally thought to proceed by a radical pathway. [24,25] In the early nineties, Ciganek and Oppolzer proved this to be a concerted process (Scheme 1) with a planar five-membered transition state involving six electrons. [26Ϫ29] It is, of course, the reverse of the well-known thermal Cope elimination of tertiary amine N-oxides, mostly leading to separate ene and hydroxylamine products.…”

Theoretical study on the mechanism of the reaction for alkene hydroaminations catalyzed by chiral aldehyde

“…Other names [32][33][34] that have been given to this reaction include "reverse Cope cyclization," "1,3-azaprotio cyclotransfer," and "Cope-type hydroamination" in the literature. This reaction was first reported by House [35,36] and Black, [37] and also highlights its considerable utility as a method for C-N bond formation. After that IM2 undergoes an aminal opening to give IM3.…”