A novel copper‐catalyzed oxidative alkylation of α‐amino carbonyl compounds with ethers has been established for the selective synthesis of α‐etherized α‐amino carbonyl compounds. This oxidative alkylation is achieved by dual C(sp3)H bond oxidative cross‐coupling, and its scope is expanded to α‐amino ketones, α‐amino esters and α‐amino amides.magnified image

A metal-free oxidative tandem coupling of activated alkenes with carbonyl C(sp 2 )-H bonds and aryl C(sp 2 )-H bonds using TBHP is established for the synthesis of 3-(2-oxoethyl)indolin-2-ones. This method allows 1,2-difunctionalization of the C-C double bond in N-arylacrylamides by simultaneous formation of two C(sp 2 )-C(sp 3 ) bonds. Scheme 1 Oxidative tandem coupling reaction. Scheme 2 Utilization of 3-(2-oxoethyl)indolin-2-ones.

A new, efficient Cu-catalyzed intramolecular C-H oxidation/acylation method has been developed for the synthesis of substituted indoline-2,3-diones (isatins). In the presence of CuCl(2) and O(2), a variety of formyl-N-arylformamides underwent the tandem reaction to afford the corresponding indoline-2,3-diones in moderate to good yields. It is noteworthy that the reaction serves as the first example of transition-metal-catalyzed transformation for the preparation of indoline-2,3-diones.

Distilling knowledge from convolutional neural networks (CNNs) is a double-edged sword for vision transformers (ViTs). It boosts the performance since the imagefriendly local-inductive bias of CNN helps ViT learn faster and better, but leading to two problems: (1) Network designs of CNN and ViT are completely different, which leads to different semantic levels of intermediate features, making spatial-wise knowledge transfer methods (e.g., feature mimicking) inefficient. (2) Distilling knowledge from CNN limits the network convergence in the later training period since ViT's capability of integrating global information is suppressed by CNN's local-inductive-bias supervision.To this end, we present Cumulative Spatial Knowledge Distillation (CSKD). CSKD distills spatial-wise knowledge to all patch tokens of ViT from the corresponding spatial responses of CNN, without introducing intermediate features. Furthermore, CSKD exploits a Cumulative Knowledge Fusion (CKF) module, which introduces the global response of CNN and increasingly emphasizes its importance during the training. Applying CKF leverages CNN's local inductive bias in the early training period and gives full play to ViT's global capability in the later one. Extensive experiments and analysis on ImageNet-1k and downstream datasets demonstrate the superiority of our CSKD. Code will be publicly available.

Oxindoles are important heterocycles found in a wide range of bioactive natural products and pharmaceutical molecules. [1,2] In addition, functionalized oxindoles are versatile synthetic blocks for the preparation of natural products and in asymmetric synthesis. As a result, considerable efforts were directed toward the development of efficient methods for their synthesis, [1][2][3][4][5][6][7] with metal-catalyzed cyclization/functionalization approaches becoming increasingly popular because of their particular efficiency. [2][3][4][5][6] However, these approaches suffer from use of both expensive and commercially not available ortho-functionalized anilines and noble-metal catalysts, thereby limiting their wide application in organic chemistry research and industry. [2][3][4] Recently, ortho-nonfunctionalized anilines were found to be viable substrates for metal-mediated direct aryl C(sp 2 )-H functionalization/cyclization reactions, however, these transformations are quite rare. [5, 6] In 2003, Hennessey and Buchwald first used ortho-nonfunctionalized anilines (achloroacetanilides) in the formation of oxindole by a variant of the Friedel-Crafts procedure through palladium-catalyzed CÀH functionalization in the presence of 2-(di-tert-butylphosphino)-biphenyl (ligand) and Et 3 N (base). [5a] Subsequently, Jia and Kündig developed a direct intramolecular oxidative coupling of an aryl C(sp 2 )-H bond and a C(sp 3 )-H center for the preparation of 3,3-disubstituted oxindoles, even though these reactions needed a stoichiometric amount of Cu catalyst combined with a base. [5b,c] Very recently, the groups of Neuville and Zhu [6a] and Liu and co-workers [6b-d] independently established a very useful access to oxindoles by Pdcatalyzed oxidative difunctionalization of alkenes in Narylacrylamides under acidic or neutral conditions. These Pd-catalyzed oxidative transformations are more fascinating than the methods reported earlier, [5] because additional functional groups can be introduced into the oxindole framework; however, use of highly expensive Pd/hypervalent iodine reagent systems make their application less desirable. [6] Herein, we report a new oxidative 1,2-alkylarylation of activated alkenes with an aryl C(sp 2 )ÀH bond and a C(sp 3 )À H bond adjacent to a heteroatom for selective synthesis of functionalized 3-(2-oxoethyl)indolin-2-ones. This oxidative 1,2-alkylarylation is catalyzed by economical and environmentally benign iron [8] and involves the use of tert-butyl hydrogenperoxide (TBHP) as oxidant and 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU, L5) as ligand (Scheme 1). To the best of our knowledge, this work represents the first example of metal-catalyzed difunctionalization of an alkene with an aryl C(sp 2 ) À H bond and a C(sp 3 ) À H bond adjacent to a heteroatom. [6b-d, 9] We initially studied the reaction of N-methyl-N-phenylmethacrylamide (1 a; 0.3 mmol) with Et 2 O (2 a; 20 equiv), FeCl 3 (5 mol %) in benzene at 120 8C under argon atmosphere (entry 1 in Table 1), and were able to isolate the d...

A simple and practical manganese(iii)-promoted tandem phosphinoylation/cyclization of 2-arylindoles/2-arylbenzimidazoles with disubstituted phosphine oxides was developed.

Scheme 3. Scope of g-amino ketones 1. Reaction conditions: 1 (0.2 mmol), 2 (0.4 mmol), AgSbF 6 (15 mol %), and CH 2 Cl 2 (2 mL) at 50 8C under argon atmosphere for 24-48 h.Scheme 4. Proposed reaction mechanism. resulting residue was purified by column chromatography on silica gel (7:1 n-hexane/ethyl acetate) to afford the desired azepine product.

A new metal-free oxidative radical [2+2+1] carbocyclization of benzene-linked 1,n-enynes with two C(sp(3))-H bonds adjacent to the same heteroatom is described. This method achieves two C(sp(3))-H oxidative functionalizations and an annulation, thus providing efficient and general access to a variety of fused five-membered carbocyclic hydrocarbons.