Search

A multicomponent cascade cyclization reaction using aryl methyl ketones, aryl amines, and enaminamide reagents to construct 3‐hydroxy‐1H‐pyrrolo[3,4‐b]quinolin‐1‐one skeleton with good substrate compatibility (50 examples) has been reported. The one‐pot, metal‐free process formed two C−C bonds, two C−N bonds, and a tetrasubstituted carbon stereocenter containing a hydroxyl group. The reaction enabled modified transformation of drug molecules and derivatization of products. [ABSTRACT FROM AUTHOR]

An oxidant-controlled divergent synthesis of a pyrrolidone fused pyrimido[1,2-b]indazole skeleton was developed through selective cyclization of an in situ generated enone intermediate and 1H-indazol-3-amine. The one-pot, metal-free process formed three C–N bonds, one C–C bond, and a tetrasubstituted carbon stereocenter containing a hydroxyl group. This method not only allowed for the synthesis of over 60 new pyrrolidone fused pyrimido[1,2-b]indazole derivatives, but was also compatible with the transformation of complex active molecules and the derivation of target products. Significantly, product 4q exhibited aggregation-induced emission (AIE) characteristics without any further modification. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A [2 + 1 + 1 + 1] cyclization reaction has been developed for the synthesis of multisubstituted β‐pyrrolidinones from commercially available aryl methyl ketones, primary amines, and ethyl nitroacetate. In this I2–DMSO‐meditated process, the C—NO2 bond of ethyl nitroacetate is cleaved, affording a C1 synthon, and the formation of two C—C and two C—N bonds and a quaternary carbon center are constructed in one pot. This method has good substrate compatibility and permits the late‐stage modification of pharmaceutical compounds. [ABSTRACT FROM AUTHOR]

A free-floating space robot exhibits strong dynamic coupling between the arm and the base, and the resulting position of the end of the arm depends not only on the joint angles but also on the state of the base. Dynamic modeling is complicated for multiple degree of freedom (DOF) manipulators, especially for a space robot with two arms. Therefore, the trajectories are typically planned offline and tracked online. However, this approach is not suitable if the target has relative motion with respect to the servicing space robot. To handle this issue, a model-free reinforcement learning strategy is proposed for training a policy for online trajectory planning without establishing the dynamic and kinematic models of the space robot. The model-free learning algorithm learns a policy that maps states to actions via trial and error in a simulation environment. With the learned policy, which is represented by a feedforward neural network with 2 hidden layers, the space robot can schedule and perform actions quickly and can be implemented for real-time applications. The feasibility of the trained policy is demonstrated for both fixed and moving targets. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The conversion of CF3‐alkenes to gem‐difluoroalkenes using reductive cross‐coupling strategy has received much attention in recent years, however, the use of green and readily available reducing salt to mediate these reactions remains to be explored. In this work, a concise construction of gem‐difluoroalkenes, which requires neither a catalyst nor a metal reducing agent, was established. Rongalite, a safe and inexpensive industrial product, was employed as both a radical initiator and reductant. This procedure was compatible with both linear and cyclic diaryliodonium salts, enabling a wide variety of substrates (>70 examples). The utility of this approach was demonstrated through gram‐scale synthesis and efficient late‐stage functionalizations of anti‐inflammatory drugs. [ABSTRACT FROM AUTHOR]

The geometrical structures, stability and electronic properties of PtmIrn and PtmIrnNO (m + n = 8 − 1 0) clusters have been studied by using density functional theory (DFT). Simple cube evolution pattern is revealed for Ir 8 − 1 0 and Ir-rich clusters. The curve of the second-order energy difference of PtnIr (9 − n) clusters shows the evident even–odd oscillations, indicating that PtIr8, Pt3Ir6, Pt5Ir4 and Pt7Ir2 clusters are more stable than their neighbors. The minimum excess energies values are seen for Pt7Ir, PtIr8 and Pt2Ir8, which means that these clusters show the stronger mixing tendency. Analysis of magnetic properties shows that the total magnetic moment contributed from Ir and Pt atoms, and the magnetic moment mainly comes from localization of the d orbit electron. All ground-state structures show an adsorption of NO at the top site of the bare cluster via the N atom. In all of the alloy clusters, NO molecule prefers to be adsorbed near the Ir atom site. Fukui function is an accurate predictor of the reactivity on a specific adsorption site in Pt–Ir alloy clusters. [ABSTRACT FROM AUTHOR]

A theoretical study was carried out of CO2 adsorption on CumCon(2 ≤ m + n ≤ 7) clusters using density functional method. Generally CO2 are located at top or bridge sites, while CO2 of Cu2Co4CO2, Co6CO2 and Cu2Co5CO2 clusters are absorbed at hollow sites. Co3CO2 and CuCo2CO2 clusters are more stable than their neighbors, while Cu2CO2 and Cu6CO2 clusters display stronger chemical stability. After adsorption, CO2 is activated with the elongation of the C–O bond owing to electrons transfer from Cu–Co clusters to 2 π u anti-bonding orbit of CO2. More charge transfer often corresponds to longer C–O bond and larger adsorption energy, and the chemical activity is stronger correspondingly. Magnetic and electronic properties are also discussed. [ABSTRACT FROM AUTHOR]

A I2‐DMSO mediated approach to introduce −OCD3 into pyrroles in situ via multicomponent cascade cyclization reaction using methyl ketones, aniline, ethyl benzoylacetate and CD3OD as readily available substrates is reported. This process realizes introduction of −OCD3 into the Hantzsch pyrrole synthesis and synthesis of deuterated alkoxy‐substituted pyrroles with formation of one C−C bond, one C−O bond and two C−N bonds in one pot. Notably, this conversion has good substrate compatibility (62 examples) and eliminates of the need for anhydrous and anaerobic operation. [ABSTRACT FROM AUTHOR]

A theoretical study was carried out of NO and H 2 O co-adsorption on Cu m Co n (2≤ m + n ≤7) clusters using density functional method. It can be found that doping H 2 O can generally promote activity of NO molecules except Co 2 NO H 2 O and Cu 2 Co H 2 O clusters. Co 4 NO H 2 O, CuCo 4 NO H 2 O and Cu 2 Co 3 NO clusters are much more stable than their neighbors, while CuCoNO H 2 O,Cu 2 CoNO H 2 O,Cu 2 Co 2 NO H 2 O,Cu 4 CoNO H 2 O,Cu 3 Co 3 NO H 2 O,Cu 6 CoNO H 2 O clusters display stronger chemical stability. Magnetic and electronic properties are also discussed. It turns out that the change of magnetic moment after H 2 O adsorption is affected not only by negative magnetic moments provided by NO and H 2 O, but also by the degree of spin polarization of Co atoms. [ABSTRACT FROM AUTHOR]

The aim of the test was to assess the nutrient composition and carbohydrate composition of more than 20 commonly used equine animal feeds in Southland. The results show that comparing the conventional composition of the 15 roughages measured. The CP content ranged from 3.31% to 19.43%, the EE content ranged from 1.23% to 2.94%, and the NDIP content ranged from 2.21% to 12.96%. Comparing the conventional composition of the five energy feeds, the CP content ranged from 5.66% to 15.63%, the EE content ranged from 1.60% to 4.08%, and the NDIP content ranged from 2.51% to 8.33%. Comparing the conventional composition of the four protein feeds, the CP content ranged from 23.75% to 46.32%, the EE content ranged from 1.26% to 15.99%, and the NDIP content ranged from 7.95% to 14.14%. Comparing 24 feedstuffs in terms of carbohydrate fraction, overall the CHO-H content of energy feeds was higher than protein feeds and most roughage, the CHO-FR content of energy feeds was higher than roughages and protein feeds, and the CHO-FS content of roughage was higher than that of energy feeds and higher than that of some protein feeds. Analysis of feeds according to the digestive characteristics of the equine genus, feeds with higher ratios on CHO-H and CHO-FR content are digested more quickly, thus the more rapidly digested of the roughage, energy and protein feeds are whole plant maize silage, dates and soya meal respectively. [ABSTRACT FROM AUTHOR]

A robust, practical, and scalable approach for the construction of 3-substituted 5-chloro-1,6-naphthyridin-4-one derivatives 13 via the addition of Grignard reagents to 4-amino-2-chloronicotinonitrile (15) was developed. Starting with various Grignard reagents, a wide range of 3-substituted 5-chloro-1,6-naphthyridin-4-one derivatives 13 were conveniently synthesized in moderate-to-good yields through addition–acidolysis–cyclocondensation. In addition, the robustness and applicability of this synthetic route was proven on a 100 g scale, which would enable convenient sample preparation in the preclinical development of 1,6-naphthyridin-4-one-based MET-targeting antitumor drug candidates. [ABSTRACT FROM AUTHOR]

To prepare immunomodulation peptides from rice protein hydrolysates (RPHs), trypsin was employed for enzymatic hydrolysis, and the immunomodulating activities of RPHs were studied using mouse peritoneal macrophage proliferation assay. The peptide fractions with the highest activity were further purified using macroporous adsorption resin, strong cation-exchange chromatography, gel filtration chromatography and reversed-phase high-performance liquid chromatography. The peptide sequence was identified as Tyr-Gly-Ile-Tyr-Pro-Arg (YGIYPR) by high-performance liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometer. Evaluating its immunomodulatory activity showed that YGIYPR enhanced the proliferation of macrophage RAW 264.7 cells in the range of 12.5–100 μg/mL, and even a minimum dose achieved good proliferation. The results demonstrated that the RPHs prepared by trypsin could serve as a source of immunomodulating peptides and the immunomodulatory peptide YGIYPR is a potential natural ingredient for manufacture of functional foods or health care products. [ABSTRACT FROM AUTHOR]

A theoretical study of NO adsorption on $$\hbox {Cu}_{m}\hbox {Co}_{n}$$ (2 $$\le m+n \le $$ 7) clusters was carried out using a density functional method. Generally, NO is absorbed at the top site via the N atom, except in $$\hbox {Cu}_{3}\hbox {NO}$$ and $$\hbox {Cu}_{5}\hbox {NO}$$ clusters, where NO is located at the bridge site. $$\hbox {Co}_{2}\hbox {NO}$$ , $$\hbox {Co}_{3}\hbox {NO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{2}\hbox {NO}$$ , $$\hbox {Co}_{5}\hbox {NO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{4}\hbox {NO}$$ and $$\hbox {Cu}_{6}\hbox {CoNO}$$ clusters have larger adsorption energies, indicating that NO of these clusters are more easily adsorbed. After adsorption, N-O bond is weakened and the activity is enhanced as a result of vibration frequency of N-O bond getting lower than that of a single NO molecule. $$\hbox {Cu}_{2}\hbox {CoNO}$$ , $$\hbox {Cu}_{3}\hbox {CoNO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{2}\hbox {NO}$$ , $$\hbox {Cu}_{3}\hbox {Co}_{3}\hbox {NO}$$ and $$\hbox {Cu}\hbox {Co}_{5}\hbox {NO}$$ clusters are more stable than their neighbours, while CuCoNO, $$\hbox {Co}_{3}\hbox {NO}$$ , $$\hbox {Cu}_{3}\hbox {CoNO}$$ , $$\hbox {Cu}_{2}\hbox {Co}_{3}\hbox {NO}$$ , $$\hbox {Cu}_{3}\hbox {Co}_{3}\hbox {NO}$$ and $$\hbox {Cu}_{6}$$ CoNO clusters display stronger chemical stability. Magnetic and electronic properties are also discussed. The magnetic moment is affected by charge transfer and the spd hybridization. [ABSTRACT FROM AUTHOR]

The structure stability and electronic properties of Cu mCo nCO (-7) clusters have been systematically investigated using density functional theory (DFT) within the generalized gradient approximation (GGA). The results indicate that the ground state structures of Cu mCo nCO clusters obtained by adsorbing CO molecules on the top sites of stable Cu mCo n clusters with C atoms and CO molecules have been activated during adsorption process. Cu2CO, CuCoCO, Cu3CoCO, Co4CO, Cu4CoCO and Cu3Co3CO clusters are stronger than other ground state clusters in thermodynamic stability. Cu2CO, Cu4CO and Cu6CO clusters show stronger chemical stability; Co2CO, Co4CO, Cu5CoCO, Cu3Co3CO, Cu2Co5CO and Co7CO clusters show better propensity to adsorb CO for these clusters have larger adsorption energies; Electronic states of Cu2Co3CO, CuCo4CO, Co5CO, Cu4Co3CO, Cu3Co4CO, CuCo6CO and Co7CO clusters are mainly influenced by those of 3d orbitals in Co and Cu atoms, the contribution to total magnetic moments of these clusters comes mainly from Co atoms and these clusters have high magnetism. [ABSTRACT FROM AUTHOR]