Copper-catalyzed [1,3]-nitrogen rearrangement ofO-aryl ketoximesviaoxidative addition of N–O bond in inverse electron flow

Abstract

The [1,3]-nitrogen rearrangement reactions of O-aryl ketoximes were promoted by N-heterocyclic carbene (NHC)-copper catalysts and BF3·OEt2 as an additive, affording ortho-aminophenol derivatives in good yields. The reaction of substrates with...

Divergent Synthesis of Anisidines by Controlling Cu‐Catalyzed [1,3]‐Methoxy Rearrangement

“…Then, oxidative addition of the NÀ O bond to the Cu atom leads to the formation of tetra-coordinated Cu complex 13. [11] The reactions of substrates having a Cbz group on the nitrogen atom using IPr ligand proceed via CÀ O bond formation at the EDG-substituted ortho position due to the contribution of canonical form 13', which is stabilized by the electronic effect of EDG, generating ortho-quinol imine 15 reversibly. In contrast, the reactions of substrates having a Piv group using bulky IPr Me ligand lead to CÀ O bond formation at the unsubstituted ortho position due to the steric effect, resulting in the of ortho-quinol imine 14 with a secondary alkyl ether moiety.…”

“…First, the cationic Cu catalyst coordinates to substrate 1 to form chelate complex 12 . Then, oxidative addition of the N−O bond to the Cu atom leads to the formation of tetra‐coordinated Cu complex 13 [11] . The reactions of substrates having a Cbz group on the nitrogen atom using IPr ligand proceed via C−O bond formation at the EDG‐substituted ortho position due to the contribution of canonical form 13’ , which is stabilized by the electronic effect of EDG, generating ortho ‐quinol imine 15 reversibly.…”

“…[6][7][8][9][10] In particular, [1,3]-alkoxy rearrangement of N-methoxyanilines 1, which have an electrondonating group (EDG), such as an alkyl or an electronrich aryl group, at the ortho position underwent domino [1,3]/ [1,2] rearrangement reactions to afford 3substituted 2-anisidines 2 (Scheme 1a). [7][8][9][10] According to our mechanistic studies including our recent research on the NÀ O bond cleavage, [11] we propose that the reaction is initiated by oxidative addition of NÀ O bond to the cationic Cu catalyst to form the tetracoordinated cationic alkoxycopper(III) complex A. Due to the contribution of the canonical form A', of which the positive charge is stabilized by the EDG, the following CÀ O bond formation occurs at the electronically preferred EDG-substituted ortho position to form ortho-quinol imine intermediate B having a tertiary alkyl ether moiety.…”

Trace water in a BF3·OEt2 system: a facile access to sulfinyl alkenylsulfones from alkynes and sodium sulfinates

“…On the other hand, BF 3 is a commonly used Lewis acid that has strong interaction with many ligands. 13 As an adduct of BF 3 and Et 2 O formed through donor–acceptor bonding, 14 BF 3 ·OEt 2 exhibits strong Lewis acidity, which enables its excellent catalytic activity 15 and allows it to participate in a series of organic syntheses, 16 such as cyclization, 17 coupling, 18 rearrangement, 19 and so on. 20 Generally, since BF 3 ·OEt 2 is very sensitive to water, when it is used as a Lewis acid to promote a reaction, strict anhydrous treatment is often required for the reaction system.…”

Lewis acid-catalyzed formal 1,3-aminomethyl migration

“…14 Thus, 1,3-migration reactions represent an important strategy for the construction of organic frameworks that are otherwise inaccessible. 15 Given the limited number of reports, however, there is a great demand for the development of a novel reaction system.…”