Copper-Catalyzed Skeletal Rearrangement of O-Propargylic Alkylaldoximes via N–O Bond Cleavage

Abstract

O-Propargylic oximes that possess a proton at the α-position of the oxime group were effectively converted to the corresponding oxiranyl N-alkenylimines via a 5-endo-dig cyclization followed by the cleavage of the N-O bond.

Metal-Involving Synthesis and Reactions of Oximes

“…165) in the presence of CuCl (10 mol %) and Cy 2 NMe (50 mol %) (in MeCN under Ar, 100 °C, 0.5−7 h, 57−93%; Scheme 77, a) 395. A suggested mechanism for this reaction includes side-on coordination of the CC bond to the copper(I) center, leading to electrophilic activation of the alkyne fragment (b).…”

Copper-Catalyzed Skeletal Rearrangements ofO-Propargylic Oximes via Cleavage of a Carbon-Oxygen Bond

“…[] Reactions of O ‐propargylic oximes using metal catalysts had yet to be reported. O ‐Propargylic oximes proved to be a rather unique platform for catalytic skeletal rearrangement reactions, involving the cleavage of the propargylic carbon–oxygen bond,[ [[#]]] the relatively weak nitrogen–oxygen bond,[] or the electrophilic oxime carbon–nitrogen double bond. [] Furthermore, the process produced a variety of multisubstituted heterocycles or nitrogenous acyclic compounds that are potentially useful in the fields of pharmaceutical or agrochemical sciences.…”

Copper‐Catalyzed Rearrangement of N‐Aryl Nitrones into Epoxyketimines

“…Accordingly, these compounds have been shown to be valuable precursors for the diastereoselective preparation of epoxy-substituted b-lactams, a-hydroxyaziridines, amino alcohols, oxazolidinones, and phytosphingosine lipid backbones (Scheme 1). [3,4] Development of a simple and general method for the preparation of a,bepoxyketimines would facilitate the exploration of the analogous reactivity of these highly substituted and densely functionalized intermediates. [1,2] Unfortunately, corresponding methods for the preparation of a,b-epoxyketimines are sparse and few alternative methods have been reported.…”

“…[1,2] Unfortunately, corresponding methods for the preparation of a,b-epoxyketimines are sparse and few alternative methods have been reported. [3,4] Development of a simple and general method for the preparation of a,bepoxyketimines would facilitate the exploration of the analogous reactivity of these highly substituted and densely functionalized intermediates.…”

“…The yield of this transformation was dependent upon the choice of reaction medium, copper salt, and N-donor ligand. Benzene, THF, and dimethylsulfoxide (DMSO) were tolerated as solvents, but the most efficient transformation was observed in acetonitrile (Table 1, entries [4][5][6][7][8]. Several copper(I) and copper(II) salts were observed to catalyze the oxygen transfer in the presence of phenanthroline, but CuCl was shown to be the optimal (Table 1 entries [8][9][10][11][12].…”