An unprecedented ruthenium(II)-catalyzed intramolecular oxidative C-N coupling method has been developed for the facile synthesis of a variety synthetically challenging tri- and tetrasubstituted pyrazoles. Dioxygen gas is employed as oxidant in this transformation. The reaction demonstrates excellent reactivity, functional group tolerance, high yields.

An efficient method for the synthesis of sulfones via nitrogen loss sulfonyl hydrazones is described. The reaction was performed in presence simple copper salt and base by utilization hydrazones, which were easily prepared from carbonyl compounds. A wide variety aryl alkyl obtained moderate to good yields.

The cyclic structure of non-ribosomal peptides (NRPs) is critical for enhancing their stability and bioactivity, which highlights the importance exploring NRP cyclization enzymes natural product discovery. Thioesterases (TEs) are crucial that catalyze formation various lactams, including macrolactams, β-lactams, γ-lactams; however, potential to produce other lactam types remains largely unexplored. In this study, we identified spinactin A (1) novel derivatives, B–E (2–5), from...

This paper presents a novel steganalysis scheme for the detection of adaptive multi-rate (AMR) audio steganography. AMR codec is used widely in mobile communication and Internet system. Due to modifiability pitch delay, several steganography schemes based on delay modulation have emerged gradually high capacity good imperceptibility. Based difference between cover stego audios continuity adjacent this proposes matrix second-order (MSDPD) features by calculating Markov transition probability...

A new family of chiral lanthanide complexes derived from (R)-binaphthol has been synthesized by a one-pot procedure using only commercially available substrates. These were evaluated for the aminolysis meso-epoxides and proved to be efficient enantioselective catalysts. The samarium complex coordinated two (R)-binaphthoxide ligands was most catalyst this series. β-Amino alcohols including heterocycles have isolated with enantiomeric excesses up 84%.

Abstract This study compared the efficiencies of two widely used automatic eddy detection algorithms—that is, winding-angle (WA) method and vector geometry (VG) method—and investigated submesoscale properties using surface current observations derived from high-frequency radars (HFRs) in Taiwan Strait. The results showed that WA streamline VG based on streamfunction field have almost same capacity for identifying eddies, but former is more competent than latter capturing size. algorithms...

Highly electrophilic aryl(2,2,2-trifluoroethyl)iodonium triflates have been used for the first time as trifluoroethyl and aryl transfer reagents in Pd-catalyzed functionalization of arylboronic acids. Electron-rich acids reacted with (2a-b) CH3CN presence Pd2(dba)3 K3PO4 at room temperature to provide arenes up 82% yield, while reactions both electron-rich -poor 2a-b DMF Pd[P(t-Bu)3]2 Cs2CO3 40 °C afforded arylation products 99% yield. This tunable protocol allows access or biaryls good...

The Mizoroki-Heck reaction represents one of the most convenient methods for carbon-carbon double bond formation in synthesis small organic molecules, natural products, pharmaceuticals, agrochemicals, and functional materials. Fluorine-containing compounds have found wide applications research areas materials life sciences over past several decades. incorporation fluorine-containing segments into target molecules by reactions is highly attractive, as these efficiently construct bonds bearing...

Second-order scattering based wave height measurement with high-frequency (HF) radar has always been subjected to problems such as distance limitation and external interference especially under low or moderate sea state. The performance is further exacerbated for a compact system small antennas. First-order Bragg investigated relate the stronger backscatter, but calibrating echo power along direction challenging. In this paper, new method presented deal calibration improve estimation from...

With the shortage of fossil energy and aggravation environmental pollution, it is urgent to develop new sources. The preparation C4 olefins from ethanol has great application prospects economic benefits. In this paper, for coupling with ethanol, relevant experiments are designed under different catalysts temperatures study relationship between conversion, selectivity temperature, explore effects catalyst combinations on conversion selectivity. According experimental data, using logistic...

This paper presents a new fully-digital high-frequency (HF) backscatter radar system for oceanographical remote sensing. The receiver is designed that employs directly radio freqency (RF) sampling, digital down-conversion, and pulse compression techniques. difference between this ordinary analogue illustrated. Results of closed-loop test field experiment conducted on the coast Eastern China Sea are given to prove good performance system.

The remarkable instruction-following capability of large language models (LLMs) has sparked a growing interest in automatically learning suitable prompts. However, while many effective methods have been proposed, the cost incurred during process (e.g., accessing LLM and evaluating responses) not considered. To overcome this limitation, work explicitly incorporates finite budget constraint into prompt learning. Towards developing principled solutions, novel connection is established between...

This letter proposes a new ultra high frequency (UHF) radar system called UHF surface dynamics parameters (USDPR). The hardware has been developed based on the currents (SCR) for an all-digital receiver platform, which realizes direct radio (RF) band-pass sampling and orthogonal demodulation of amplified echo, as compared with traditional intermediate (IF) receivers. Closed-loop test field proves correctness design.

A series of complex 2,2,2-trifluoroethyl fatty acid esters were synthesized by the reaction acids and phenyl(2,2,2-trifluoroethyl)iodonium triflate in presence Cs2CO3. The at room temperature without any other additive provided corresponding up to quantitative yield. conjugated carbon–carbon double bonds, unprotected hydroxyl group, amido functionalities substrates are all tolerated reaction. Compared known synthetic methods, advantages this include mild conditions, good functional group...

This paper proposes a novel ultra high frequency (UHF) radar system for river dynamics parameters monitoring. As compared with conventional system: (1) Intermediate (IF) sampling mode of traditional superheterodyne receivers is replaced by the direct radio (RF) band-pass and orthogonal demodulation (2) Multi-channel antenna divided into two units, which realizes that one operation obtains two-dimensional current vectors. Results field test EKZ-I measurement at Xiantao Hydrological Station,...

Abstract An asymmetric intermolecular Rauhut‐Currier reaction of α′‐alkylidene 2‐cyclohexenones and (7‐aza)isatinylidene malononitriles is realized under the double activation catalysis natural quinine 2‐mercaptobenzoic acid, finally affording formal 3‐arylated spiro (7‐aza)oxindole derivatives in fair to excellent enantioselectivity after a tandem cyclization/aromatization process (up 96% ee ). magnified image