From Alkenes to Isoxazolines via Copper-Mediated Alkene Cleavage and Dipolar Cycloaddition

Abstract

An unprecedented copper-mediated anion transformation is reported, along with selective CC double bond cleavage and dipolar cycloaddition reaction from simple alkenes and inexpensive copper nitrate. Various transformations demonstrate the generality of this method. Further mechanistic investigation indicates a novel ionic pathway for alkene cleavage and highlights the coeffect of iodide and boric acid as additives on the inhibition of well-documented competitive nitration byproducts.

Pd/Cu Dual‐Catalyzed Asymmetric Synthesis of Highly Functional All‐Carbon Quaternary Stereocenters from Vinyl Carbonates

“…Then other chiral diphosphines were examines (entries 3-12, L2-L11), and among these the SegPhos (cf., L4) family of ligands provided a first structural clue for further optimization. Based on the comparison of both yield and er values, we selected (R)-DTBM-SegPhos L4 (37 % yield, er = 78.5 : 21.5, entry 5) as the preferred chiral ligand to scrutinize the role of the Lewis acid in more detail (entries [13][14][15][16][17][18][19][20][21].…”

“…In this latter case, the boronic ester 3 could be isolated (see the Supporting Information) in 25 % isolated yield. [20] We assume that the base (LiHMDS) first deprotonates B(OH) 3 and eventually forms some kind of lithium borate intermediate (Scheme 4) [21] able to stabilize the dienolate. [22] The presence of Cu(OAc) 2 provokes a transmetalation process allowing for substrate turnover.…”

Copper-catalyzed radical oxyallylation of olefins for the construction of alkene-containing isoxazolines

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Among them, the oxyallylation of alkenes is a particularly useful reactions, because the alkenes motif in the resulting products offer rich possibilities for synthetic manipulations. Despite significant advances in the oxyfunctionalization of alkenes, [17][18][19][20][21][22][23][24][25][26] oxyallylation of alkenes have been little explored. France and co-workers developed the palladium-catalyzed oxyallylation of unactivated alkenes using phenols, alcohol and carboxylic acid as the nucleophiles (Scheme 1a).…”

Direct Nitration of Vinylcycles with Copper Nitrate

“…Nevertheless, several challenges need to be overcome (Scheme 1b): (a) cyclopropanes are fragile with Lewis acid, 8 leading to ring-opening reactions; (b) inhibition of nitroethanol byproducts by welldocumented olefinic competitive nitration reaction; 9 (c) cleavage of C�C double bond might occur in the presence of Cu(NO 3 ) 2 , generating nitrile oxides during the reaction. 10 Herein, we report a general method for straightforward nitration of various vinylcyclopropanes under mild conditions via an ionic pathway, where cheap and hypotoxic copper nitrate trihydrate is used as nitro source (Scheme 1a). 11 Furthermore, the given method could be extended to other vinylcycles.…”