Metal-Free C–H Alkyliminylation and Acylation of Alkenes with Secondary Amides

Abstract

Carbon–carbon bond formation by metal-free cross-coupling of two reactants with low reactivity represents a challenge in organic synthesis. Secondary amides and alkenes are two classes of bench-stable compounds. The low electrophilicity of the former and low nucleophilicity of the latter make the direct coupling of these two partners challenging yet highly desirable. We report herein an unprecedented intermolecular reaction of secondary amides with alkenes to afford α,β-unsaturated ketimines or enones, which are versatile intermediates for organic synthesis and are prevalent in bioactive compounds and functional materials. Our strategy relies on the chemoselective activation of the secondary amide with trifluoromethanesulfonic anhydride (Tf2O)/2-fluoropyridine to generate a highly reactive nitrilium intermediate, which reacts efficiently with alkenes. This metal-free synthesis is characterized by its mild reaction conditions, excellent functional group tolerance and chemoselectivity, allowing the preparation of multi-functionalized compounds without using protecting groups.

Pearson correlation coefficient as a measure for certifying and quantifying high-dimensional entanglement

“…(b) We consider two types of coloured-noise mixed with maximally entangled state. In one of the types, coloured-noise state having perfect correlation in the computational basis is mixed with the maximally entangled state [32]. For this family of states, we find that one can choose two appropriate MUBs so that the sum of two PCCs being greater than 1 gives the necessary and sufficient condition for certifying entanglement; quantification of entanglement is also obtained similar to the earlier cases in terms of Negativity.…”

“…Next, considering the other approaches that have been proposed for the characterization of entanglement for high-dimensional bipartite systems, the following are particularly noteworthy. A scheme based on the sum of mutual information using two mutually unbiased bases (MUBs) has been invoked to certify various noisy mixed entangled states in higher-dimensional cases using the notion that a bipartite multidimensional state in even dimension can be regarded as an ensemble of bipartite qubit states [32]; however, this scheme provides only sufficient criterion for detecting entanglement and quantifies entanglement in terms of entanglement of formation, essentially restricted to the maximally entangled state [33]. Another approach based on the notion of mutual predictability has led to the argument that the condition of the sum of mutual predictabilities pertaining to MUBs exceeding a certain bound can serve as a necessary and sufficient criterion for certifying entanglement of pure and isotropic mixed states in any dimension [34].…”

The fabrication of optical and magnetic responsive deforming multilayered film

“…As shown in Figures and , the bending property and bending recovery property of the multilayered films (electrospinning 15–30 min of the precursor solution containing 5 wt % 5CB) fabricated by electrospinning method with parallel electrode were better than that of plate electrode. The reason is that electrospun PVA/5CB fiber can be more orderly arranged by the parallel electrode collector . Hence, parallel electrode electrospinning method is more suitable for the further fabrication of the optical‐responsive deforming multilayered film.…”

“…The reason is that electrospun PVA/5CB fiber can be more orderly arranged by the parallel electrode collector. 28 Hence, parallel electrode electrospinning method is more suitable for the further fabrication of the opticalresponsive deforming multilayered film.…”

Direct Regioselective Synthesis of Tetrazolium Salts by Activation of Secondary Amides under Mild Conditions

“…On the basis of prior literature, 10 we postulated that amide 8 , via formation of an iminium triflate and ensuing 2-F-Py-mediated deprotonation, would lead to a nitrilium ion 10 . That intermediate could then react with the alkyl azide in a formal (3 + 2) cycloaddition (Scheme 5).…”