The Cover Feature shows transformations of triglycerides into fatty amines, amides, and nitriles using NH3 and H2. More information can be found in the Full Paper by Jamil et al on page 3115 in Issue ...13, 2019 (DOI: 10.1002/cssc.201900365).
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•The amide-decorated carbon dots exhibit thermosensitivity and high cloud point.•A limit of detection of 3.41 nM for Cd2+ determination is achieved.•The interaction between amide and ...Cd2+ causes the fluorescence enhancement.•Fluorescence enhancement effect renders a broad detection range in quantifying Cd2+.
As highly toxic metal ions, cadmium ions (Cd2+) are prevalent in varying concentrations around the world. The establishment of an accurate and effective method for Cd2+ determination with high sensitivity and selectivity is of particular concern. The present work fabricated a fluorescence chemosensor for the detection of Cd2+ based on functionalized carbon dots (CDs), which were hydrothermally prepared using amidated hyperbranched-polyethyleneimine (HPEI). As investigated by FTIR, NMR, and XPS, the stably grafted amide groups endowed the CDs with thermosensitivity and high cloud point due to the change in hydrophilic-hydrophobic behaviors. The CDs chemosensor with optimal amidation degree exhibited high sensitivity, selectivity, and stability in the determination of Cd2+ from various water environments. Notably, the fluorescence intensity enhanced with the increase of Cd2+ concentration, originating from the improved structure rigidity caused by the interactions between grafted amides and Cd2+. These impressive features made the CDs not only sensitive to detecting Cd2+ in low-concentration solutions with a limit of detection of 3.41 nM (the lowest known value for Cd2+ detection) but also accurate for the quantification in high-concentration solutions with a detectable Cd2+ concentration of 6.0 × 10−2 M. Owing to the broad detection range, the CDs developed in present work show great potential applications in various scenarios.
Air-stable and convenient amidobenziodoxolones as an amidating reagent were disclosed to enable direct amidation on a wide range of C(sp2)–H bonds of (hetero)arenes and alkenes, as well as ...unactivated C(sp3)–H bonds under RhIII catalysis. The approach to access 49 examples of structurally diverse amides is featured by mild conditions, complete chemoselectivity and regioselectivity, broad substrate scope (not limited to strongly heterocyclic coordinating groups), and tolerance of valuable functional substituents, such as unprotected amine and hydroxyl groups. The synthetic applicability of this protocol is also demonstrated by late-stage functionalization of biologically important scaffolds.
This work proposes a facile and new approach that uses graft copolymerization and amidation reaction to prepare shape memory polymer (SMP) based on natural rubber (NR). The poly(methyl methacrylate) ...modified NR (MGNR) is cross-linked with diamine through an amidation reaction. In this kind of approach, a novel type of cross-linked MGNR with a three-dimensional network of amide linkage was prepared. The solvent resistance, mechanical properties, and phase morphology of MGNRs were significantly improved after being cross-linked by a diamine cross-linker. Additionally, the cross-linked MGNR40 also exhibited excellent shape fixation and shape recovery. This is a direct result of the vitrification of the grafted PMMA domains at low temperatures, preventing elastic recovery. Meanwhile, a cross-linked network from amide linkage facilitates recovery force upon heating. Hence, the shape memory performance of MGNRs can be tuned with both grafted PMMA content and the degree of diamine cross-link. The strategy in this research work offered an effective and convenient method to obtain cross-linked MGNR with unique molecular architecture. Consequently, this cross-linked MGNR delivered excellent mechanical strength and shape memory performance.
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•A new molecular design of thermo-responsive SMP was successfully synthesized.•Curing MGNR with an amidation reaction was evaluated and characterized.•Mechanical performance was significantly improved with the amidation reaction.•Amidation cured MGNR exhibited excellent shape memory performance.•Vitrification and amide linkage provided good shape fixity and shape recovery.
A mild, oxidant‐free, and selective Cp*CoIII‐catalyzed amidation of thioamides with robust dioxazolone amidating agents via C(sp3)−H bond activation to generate the desired amidated products is ...reported. The method is efficient and allows for the C−H amidation of a wide range of functionalized thioamides with aryl‐, heteroaryl‐, and alkyl‐substituted dioxazolones under the Cp*CoIII‐catalyzed conditions. The observed regioselectivity towards primary C(sp3)−H activation is supported by computational studies and the cyclometalation is proposed to proceed by means of an external carboxylate‐assisted concerted metalation/deprotonation mechanism. The reported method is a rare example of the use of a directing group other than the commonly used pyridine and quinolone classes for Cp*CoIII‐catalyzed C(sp3)−H functionalization and the first to exploit thioamides.
A mild, efficient, and selective method for C(sp3)−H bond activation and amidation that employs thioamides as the directing group, with aryl‐, heteroaryl‐, and alkyl‐substituted dioxazolones under CoIIICp* catalytic conditions, is described.
Alkane-gem-diboronic acids have emerged as versatile organoboron catalysts for dehydrative amidation of α-amino acids. A phenol-substituted multiboron catalyst with a B–C–B structure outperformed ...simple arylboronic acids in the condensation of α-amino acids with suppressed epimerization of electrophiles. gem-diboronic acid catalysis were compatible with various O, N, and S-functionalized α-amino acids bearing N-protecting groups including common carbamates used in peptide synthesis (Boc, Cbz, Fmoc). N-trifluoroacetyl protection enabled an unprecedented catalytic dehydrative peptide synthesis at room temperature. Preliminary mechanistic studies revealed carboxylate-binding nature of gem-diboronic acids, orthogonal to the activation of carboxylic acids by arylboronic acids. The distinctive reactivity of the gem-diboronic acids would open prospects for mild catalytic peptide condensation.
The Cover Feature shows the path leading from bio‐based lactic acid to acrylonitrile. In the first stage, the direct amidation of lactic acid is catalyzed by MFI zeolites. The obtained lactamide is ...subsequently dehydrated to acrylonitrile. More information can be found in the Full paper by D. Mack et al. on page 1653 in Issue 8, 2019 (DOI: 10.1002/cssc.201802914).
The synthesis, characterization, and catalytic performance of an iridium(III) catalyst with an electron-deficient cyclopentadienyl ligand (Cp
IrI
) are reported. The Cp
IrI
catalyst was synthesized ...by complexation of a precursor of the Cp
ligand with Ir(cod)OAc
, followed by oxidation, desilylation, and removal of the COD ligand. The electron-deficient Cp
IrI
catalyst enabled C-H amidation reactions assisted by a weakly coordinating ether directing group. Experimental mechanistic studies and DFT calculations suggested that the high catalytic performance of Cp
IrI
is due to its electron-deficient nature, which accelerates both C-H activation and Ir
-nitrenoid formation.
Nirmatrelvir (1), a novel and specific inhibitor of the SARS-CoV-2 3C-like protease, was developed by Pfizer scientists in mid 2020. Efforts to develop a scalable process to manufacture nirmatrelvir ...were undertaken with a great sense of urgency, as there were no effective treatments available for the worldwide patient population at that time. We used a convergent approach to generate this molecule. The first two steps used to generate the western fragment of nirmatrelvir from l-tert-leucine, ethyl trifluoroacetate, and a 3.1.0 bicyclic proline derivative are described here. This is the first of a series of four papers describing the commercial process of the development of nirmatrelvir.
Give Me an Ar, give Me an N! Arylation of the methyl group in a simple derivative of readily available alanine under palladium catalysis was followed by intramolecular amidation at the same position ...to give chiral α‐amino‐β‐lactams with a wide range of aryl substituents (see scheme; Phth=phthaloyl). The α‐amino‐β‐lactams were obtained in moderate to high yields with good functional‐group tolerance and high diastereoselectivity.
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