The combination of transition‐metal catalysis and organocatalysis increasingly offers chemists opportunities to realize diverse unprecedented chemical transformations. By combining iridium with ...chiral thiourea catalysis, direct enantioselective reductive cyanation and phosphonylation of secondary amides have been accomplished for the first time for the synthesis of enantioenriched chiral α‐aminonitriles and α‐aminophosphonates. The protocol is highly efficient and enantioselective, providing a novel route to the synthesis of optically active α‐functionalized amines from the simple, readily available feedstocks. In addition, the reactions are scalable and the thiourea catalyst can be recycled and reused.
The first enantioselective reductive cyanation and phosphonylation of secondary amides have been achieved by the combination of iridium with chiral thiourea catalysis. The protocol is highly efficient and enantioselective, providing a novel route for the synthesis of optically active α‐aminonitriles and α‐aminophosphonates from bench‐stable feedstocks.
Summary of main observation and conclusion
The efficient construction of functionalized polycyclic structures is an important objective in organic synthesis. Herein, we disclose a three‐step “2 + n” ...annulation method for the transformation of cyclic ketones to fused enimines and enones. The method relies on the Suzuki coupling reaction and the amide reductive alkenylation reaction. A series of fused bicyclic (6/6, 6/7, 8/7) and tricyclic (6/6/6; 6/6/7, 6/5/7) ring systems bearing an α,β‐enimine or an α,β‐enone functionality have been synthetized in good overall yields.
An expedient protocol for the efficient assembly of cyclic ketones and ω‐unsaturated amides in a “2 + n” manner to produce fused enimines and enones has been developed.
N
-Acylpyrrole-type amides are a class of versatile building blocks in asymmetric synthesis. We report that by employing Ni(COD)
2
/2,2′-bipyridine (5 mol%) catalytic system, the direct, catalytic ...alcoholysis of
N
-acylpyrrole-type aromatic and aliphatic amides with both primary and secondary alcohols can be achieved efficiently under very mild conditions (rt, 1 h) even at gram scale. By increasing the catalyst loading to 10 mol%, prolonging reaction time (18 h), and/or elevating reaction temperature to 50 °C/80 °C, the reaction could be extended to both complex and hindered
N
-acylpyrroles as well as to
N
-acylpyrazoles,
N
acylindoles, and to other (functionalized) primary and secondary alcohols. In all cases, only 1.5 equiv. of alcohol were used. The value of the method has been demonstrated by the racemization-free, catalytic alcoholysis of chiral amides yielded from other asymmetric methodologies.
The combination of transition‐metal catalysis and organocatalysis increasingly offers chemists opportunities to realize diverse unprecedented chemical transformations. By combining iridium with ...chiral thiourea catalysis, direct enantioselective reductive cyanation and phosphonylation of secondary amides have been accomplished for the first time for the synthesis of enantioenriched chiral α‐aminonitriles and α‐aminophosphonates. The protocol is highly efficient and enantioselective, providing a novel route to the synthesis of optically active α‐functionalized amines from the simple, readily available feedstocks. In addition, the reactions are scalable and the thiourea catalyst can be recycled and reused.
The first enantioselective reductive cyanation and phosphonylation of secondary amides have been achieved by the combination of iridium with chiral thiourea catalysis. The protocol is highly efficient and enantioselective, providing a novel route for the synthesis of optically active α‐aminonitriles and α‐aminophosphonates from bench‐stable feedstocks.
Near-infrared (NIR) and mid-infrared (MIR) technology combined with supervised pattern recognition based on partial least-squares discriminant analysis (PLSDA) was attempted to classify and verify ...six different concocted pieces of 600 Areca catechu L. samples and the influence of fingerprint information preprocessing methods on recognition performance was also investigated in this work. In conclusion, PLSDA can rapidly and effectively extract otherness of fingerprint information from NIR and MIR spectra to identify different concocted herbal pieces of A. catechu.
Rapid and sensitive recognition of herbal pieces according to different concocted processing is crucial to quality control and pharmaceutical effect. Near-infrared (NIR) and mid-infrared (MIR) technology combined with supervised pattern recognition based on partial least-squares discriminant analysis (PLSDA) was attempted to classify and recognize six different concocted processing pieces of 600 Areca catechu L. samples and the influence of fingerprint information preprocessing methods on recognition performance was also investigated in this work. Recognition rates of 99.24%, 100% and 99.49% for original fingerprint, multiple scatter correct (MSC) fingerprint and second derivative (2nd derivative) fingerprint of NIR spectra were achieved by PLSDA models, respectively. Meanwhile, a perfect recognition rate of 100% was obtained for the above three fingerprint models of MIR spectra. In conclusion, PLSDA can rapidly and effectively extract otherness of fingerprint information from NIR and MIR spectra to identify different concocted herbal pieces of A. catechu.
The direct transformation of amides has attracted considerable attention in recent years, which has resulted in many valuable synthetic methods. However, the direct, catalytic decarbamoylative ...cross-couplings of native amides remain underexplored and challenging. Here, we demonstrate that catalytic intermolecular decarbamoylative C–C arylation and C–B borylation of N-acylpyrrole-based tertiary amides can be achieved using nickel⋅N-heterocyclic carbene (NHC) catalysis, yielding biaryl compounds and boronic esters, respectively. Furthermore, this method can be extended to other N-acylpyrrole-type amides, such as N-acylindoles and N-acylcarbazoles, and for the C–B borylation, to N,N-diphenyl-type amides, which act as surrogates for electrophilic aryl and alkyl partners. To our knowledge, this represents the first example of catalytic decarbamoylative functionalization of planar N-acylpyrrole-type amides. Importantly, we propose the concept of heteroaromatization (aza-aromaticity) effect to account for the high electrophilicity of planar N-acylpyrrole-type amides.
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•A general route to biaryls and arylboronic esters from N-acylpyrrole-type amides•Halogen-free and nonprecious-metal-based catalytic approach•Ni/NHC-catalyzed decarbamoylation via tandem C–N and C–C bond cleavages•The concept of heteroaromatization effect of planar N-acylpyrrole-type amides
The high stability of amides has hampered their usage as coupling components in the transition-metal catalyzed cross-coupling reactions. Chen et al. report a general strategy for the Ni/NHC-catalyzed decarbamoylative of N-acylpyrrole-type amides, providing a halogen-free and nonprecious-metal-based catalytic approach to biaryls and arylboronic esters.
The development of efficient, low-cost, for water splitting, particularly those stable, non-noble-metal electrocatalysts that can catalyze both the hydrogen evolution reaction （HER） at the cathode ...and oxygen evolution reaction （OER） at the anode, is a challenge. We have developed a facile method for synthesizing CoSe2 nanoparticles uniformly anchored on carbon fiber paper （CoSe2/CF） via pyrolysis and selenization of in situ grown zeolitic imidazolate framework-67 （ZIF-67）. CoSe2/CF shows high and stable catalytic activity in both the HER and OER in alkaline solution. At a low cell potential, i.e., 1.63 V, a water electrolyzer equipped with two CoSe2/CF electrodes gave a water-splitting current of 10 mA.cm-2. At a current of 20 mA-cm-2, it can operate without degradation for 30 h. This study not only offers a cost-effective solution for water splitting but also provides a new strategy for developing various catalytic nanostructures by changing the metal-organic framework precursors.
The cover picture shows
a typical building within the Campus of Xiamen University displaying Chen Jiageng (Tan Kah Kee)'s style. Just like many beautiful buildings designed and constructed by human, ...Nature “designs and constructs” a huge number of useful molecules with fascinating structures called natural products. Many natural products possess a fused six or seven‐membered carbocyclic unity. On page 315–322, the Huang's group disclosed a three‐step “2+
n
” annulation method for the construction of fused six and seven‐membered carbocyclic enimines and enones. The method starts from simple cyclic ketones and terminal olefinic amides, and relies on both the Suzuki coupling reaction and the olefin‐amide based Friedel‐Crafts type acylating reaction, a method developed by Huang and coworkers.
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The origin of tumor-infiltrating Tregs, critical mediators of tumor immunosuppression, is unclear. Here, we show that tumor-infiltrating naive CD4＋ T cells and Tregs in human breast cancer have ...overlapping TCR repertoires, while hardly overlap with circulating Tregs, suggesting that intratumoral Tregs mainly develop from naive T cells in situ rather than from recruited Tregs. Furthermore, the abundance of naive CD4＋ T cells and Tregs is closely correlated, both indicating poor prognosis for breast cancer patients. Naive CD4＋ T cells adhere to tumor slices in proportion to the abundance of CCL18-producing macrophages. Moreover, adoptively transferred human naive CD4＋ T cells infil- trate human breast cancer orthotopic xenografts in a CCL18-dependent manner. In human breast cancer xenografts in humanized mice, blocking the recruitment of naive CD4＋ T cells into tumor by knocking down the expression of PITPNM3, a CCL18 receptor, significantly reduces intratumoral Tregs and inhibits tumor progression. These findings suggest that breast tumor-infiltrating Tregs arise from chemotaxis of circulating naive CD4＋ T cells that differentiate into Tregs in situ. Inhibiting naive CD4＋ T cell recruitment into tumors by interfering with PITPNM3 recognition of CCL18 may be an attractive strategy for anticancer immunotherapy.
Two kinds of latex sponge (80 NR and 0 NR) with different natural latex contents were exposed to 100 ℃ by accelerated hot air aging method. Their thermal-oxidative aging behavior was investigated by ...using yellowness index, whiteness index, crosslinking density and indentation hardness, and the hot air aging rule of the materials was discussed. The results showed that the yellowness index of 80 NR was always higher than that of 0 NR, while the whiteness index was always lower than the latter. The crosslinking density of 80 NR was always bigger than that of 0 NR, so the latex sponge of 80 NR was more prone to molecular chain breakage and crosslinking reaction. The indentation hardness of 80 NR was affected obviously by aging time, and would increase sharply in a short time. The indentation hardness of 0 NR was linearly correlated with aging time and had a small increase. The aging resistance of 0 NR was better than that of 80 NR.
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