Recent advancement and novel application of organocatalyzed aldol condensation reactions: A comprehensive review

Background: Aldol reactions play an important role in the development of organic synthesis-owing to their critical importance for the forming of carbon-carbon bonds while concurrently one or two chiral centers come into being. In the modern scenario, the Aldol condensation reaction has arisen as perhaps the most significant reaction for the formation of novel medicinal agents exhibits promising pharmacological activities. Objective: The purpose of this study is to present newer synthetic approaches through Aldol condensation reaction for the synthesis of diverse scaffolds to explore the promising various types of biological activities. Methods: Aldol condensation concerns the nucleophilic addition reaction of a ketone enolate to an aldehyde to form aldol or β- hydroxy ketone. Occasionally, the aldol addition product losing water molecule yields an α, β-unsaturated ketone. Results: Results showed that amino acids and all lengths of peptides are utilized as chiral catalysts. As of now, the arrangement of catalysts that have been accounted for is intensely one-sided towards proline. This is to some degree because of its exceptional status among the normally happening amino acids as an auxiliary amine and to its restricted underlying adaptability. Conclusion: The present study thus provides useful insight concerning the promising coherent way for the synthesis of prolinamide analogue of proline, through a direct asymmetric aldol condensation reaction. Thus, the current study summarizes various Aldol condensation reactions for the synthesis of novel agents as well as their promising pharmacological importance.

Factors Influencing Consumers Purchase Intention on The Live Streaming Shopping Platform in China

Live streaming shopping has become more and more popular in recent years, so it is quite necessary to illustrate how we can increase the customers’ purchase intention. A mixed-method study is developed, including an interview of broadcaster’s perspective and a survey of customers' perspectives to learn about consumers' concerns when shopping on live streaming platforms. The research was approached interactively, adapting the method in response to the findings discovered from the interviews. Few consumers have a habit of watching live streaming shopping regularly. Consumers want to try something new on the live streaming platform no matter bought this product or have seen this brand before. Broadcaster’s identification has not affected consumer’s purchase intention much. However, the consumer would trust broadcasters and choose to buy products from their live room. From the broadcaster’s perspective, they need a platform to teach them from zero to one, and network traffic is a big problem for them. In addition, product trust is more effective than broadcaster trust for the moment. Therefore, sellers are needed to improve their communication and describing skills. This paper also emphasized that the e-commerce approach should not only be competitive in terms of pricing but also in terms of quality in order to meet client demand. Furthermore, many customers believe that false propaganda should not be broadcast on live streaming platforms. As a result, broadcasters should be professionally and skillfully trained. This paper will give broadcaster and e-commerce companies suggestions on the affection of purchase intention during live streaming shopping. In addition, this paper gives future studies some basic studies and suggestions.

Synthesis and Reactivity of Group 12 β-Diketiminate Coordination Complexes

<p>The variable β-diketiminate ligand poses as a suitable chemical environment to explore unknown reactivity and functionality of metal centres. Variants on the β-diketiminate ligand can provide appropriate steric and electronic stabilization to synthesize a range of β-diketiminate group 12 metal complexes. This project aimed to explore various β-diketiminate ligands as appropriate ancillary ligands to derivatise group 12 element complexes and investigate their reactivity. A β-diketiminato-mercury(II) chloride, [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]HgCl, was synthesized by addition of [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]Li to mercury dichloride. Attempts to derivatise the β-diketiminato-mercury(II) chloride using salt metathesis reactions were unsuccessful with only β-diketiminate ligand degradation products being observed in the ¹H NMR. A β-diketiminato-cadmium chloride, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂]CdCl, was derivatized to a β-diketiminato-cadmium phosphanide, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂]Cd P(C₆H₁₁)₂, via a lithium dicyclohexyl phosphanide and a novel β-diketiminato-cadmium hydride, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂]CdH, via Super Hydride. Initial reactivity studies of the novel cadmium hydride with various carbodiimides yielded a β-diketiminato-homonuclear cadmium-cadmium dimer, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂Cd]₂, which formed via catalytic reduction of the cadmium hydride. Attempts to synthesize an amidinate insertion product via a salt metathesis reaction or a ligand exchange reaction proved unsuccessful but a novel cadmium amidinate, [{CH(N-C₆H₁₁)₂}₂{CH(N-C₆H₁₁)(N(H)-C₆H₁₁)}Cd], was synthesized from addition of dicyclohexyl formamidine to bis-hexamethyldisilazane cadmium. A β-diketiminato-zinc(II) bromide, [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]ZnBr, was synthesized by addition of [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]Li to zinc dibromide. The β-diketiminato-zinc(II) bromide was derivatized to a variety of complexes (including amides and phosphanides) by a salt metathesis reaction. Chalcogen addition reactions were performed from [o-C₆H₄{C(CH₃)=N-2,6-iPr₂C₆H₃}{NH(2,6-iPr₂C₆H₃)}ZnP(C₆H₁₁)₂] to produce double addition products from sulfur, selenium and tellurium. Chalcogen addition reactions from [o-C₆H₄{C(CH₃)=N-2,6-iPr₂C₆H₃}{NH(2,6-iPr₂C₆H₃)}ZnP(C₆H₅)₂] produced a double addition product for selenium and a β-diketiminato-zinc(II) tellunoite bridged dimer, [o-C₆H₄{C(CH₃)=N-2,6-iPr₂C₆H₃}{NH(2,6-iPr₂C₆H₃)}Zn]Te, from tellurium. A total of 14 compounds were characterized via X-ray diffraction. Photoluminescence studies of the β-diketiminato-zinc(II) compounds were conducted where it was proposed that an electron transfer from the lone pair on the hetero-atom influenced the quantum yield and fluorescence intensities.</p>

Synthesis and Reactivity of Group 12 β-Diketiminate Coordination Complexes

<p>The variable β-diketiminate ligand poses as a suitable chemical environment to explore unknown reactivity and functionality of metal centres. Variants on the β-diketiminate ligand can provide appropriate steric and electronic stabilization to synthesize a range of β-diketiminate group 12 metal complexes. This project aimed to explore various β-diketiminate ligands as appropriate ancillary ligands to derivatise group 12 element complexes and investigate their reactivity. A β-diketiminato-mercury(II) chloride, [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]HgCl, was synthesized by addition of [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]Li to mercury dichloride. Attempts to derivatise the β-diketiminato-mercury(II) chloride using salt metathesis reactions were unsuccessful with only β-diketiminate ligand degradation products being observed in the ¹H NMR. A β-diketiminato-cadmium chloride, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂]CdCl, was derivatized to a β-diketiminato-cadmium phosphanide, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂]Cd P(C₆H₁₁)₂, via a lithium dicyclohexyl phosphanide and a novel β-diketiminato-cadmium hydride, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂]CdH, via Super Hydride. Initial reactivity studies of the novel cadmium hydride with various carbodiimides yielded a β-diketiminato-homonuclear cadmium-cadmium dimer, [CH{(CH₃)CN-2,6-iPr₂C₆H₃}₂Cd]₂, which formed via catalytic reduction of the cadmium hydride. Attempts to synthesize an amidinate insertion product via a salt metathesis reaction or a ligand exchange reaction proved unsuccessful but a novel cadmium amidinate, [{CH(N-C₆H₁₁)₂}₂{CH(N-C₆H₁₁)(N(H)-C₆H₁₁)}Cd], was synthesized from addition of dicyclohexyl formamidine to bis-hexamethyldisilazane cadmium. A β-diketiminato-zinc(II) bromide, [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]ZnBr, was synthesized by addition of [o-C₆H₄{C(CH₃)=N-2,6- iPr₂C₆H₃}{NH(2,6- iPr₂C₆H₃)}]Li to zinc dibromide. The β-diketiminato-zinc(II) bromide was derivatized to a variety of complexes (including amides and phosphanides) by a salt metathesis reaction. Chalcogen addition reactions were performed from [o-C₆H₄{C(CH₃)=N-2,6-iPr₂C₆H₃}{NH(2,6-iPr₂C₆H₃)}ZnP(C₆H₁₁)₂] to produce double addition products from sulfur, selenium and tellurium. Chalcogen addition reactions from [o-C₆H₄{C(CH₃)=N-2,6-iPr₂C₆H₃}{NH(2,6-iPr₂C₆H₃)}ZnP(C₆H₅)₂] produced a double addition product for selenium and a β-diketiminato-zinc(II) tellunoite bridged dimer, [o-C₆H₄{C(CH₃)=N-2,6-iPr₂C₆H₃}{NH(2,6-iPr₂C₆H₃)}Zn]Te, from tellurium. A total of 14 compounds were characterized via X-ray diffraction. Photoluminescence studies of the β-diketiminato-zinc(II) compounds were conducted where it was proposed that an electron transfer from the lone pair on the hetero-atom influenced the quantum yield and fluorescence intensities.</p>

Acetate Facilitated Nickel Catalyzed Coupling of Aryl Chlorides and Alkyl Thiols

We report a mild, fast and convenient catalytic system for the coupling of aryl chlorides with primary, secondary, as well as previously challenging tertiary alkyl thiols using an air-stable nickel(II) precatayst in combination with the low-cost base potassium acetate at room temperature. This new catalytic system tolerates a variety of functional groups and enables the generation of thioethers for a wide range of substrates, including pharmaceutical compounds in excellent yields. Chemoselec-tive functionalization of disubstituted substrates was demonstrated. Kinetic and NMR-studies, as well as DFT computations support a Ni(0)/Ni(II) catalytic cycle and identify the oxidative addition product as the resting state. Acetate coordination and subsequent acetate facilitated formation of a thiolate complex via internal deprotonation play a key role in the catalytic cycle.

Photoredox Catalyzed Ring-Opening Addition Reaction Between Benzyl Bromides and Cyclic Ethers

A novel nucleophilic reaction between cyclic ethers and benzyl bromides is achieved under photoredox catalysis. The reaction proceeds through a single electron transfer (SET) pathway rather than a common SN2 mechanism. By two steps of reduction and oxidation, a benzyl bromide heterolyzes to give a carbocation and bromide ion under mild conditions, and then a cyclic ether captures both the carbocation and bromide ion to afford the addition product.

Unique Digoldgermanes: Structural Characteristics, Dynamic Behaviour and Distinctive Reactions

Digoldgermanes with a gold coordinated by a dialkylgermylene ligand, R’2Ge(AuPR3)(AuGeR’2) (3a; R = Me, 3b; R = Et), were synthesized as green solids through the reactions of stable dialkylgermylene 1 with R3PAuCl followed by the reduction with KC8 at ambient temperatures. The structural characteristics of 3a and 3b were elucidated using NMR spectroscopy, X-ray crystallography, and DFT calculations. An intense absorption maximum was observed at 590 nm in the UV-vis spectrum of 3a in hexane. A pendular motion of AuPR3 group between Ge(IV) and Ge(II) of 3a and 3b occurring in the NMR time scale was found by the dynamic 1H NMR analysis, suggesting that the Ge(II) ligand has an enhanced electrophilicity to be attacked by the nucleophilic gold atom which closes to ‒1 oxidation state. DFT calculations of 3a revealed the existence of high-lying σ(Ge-Au) type HOMO and low-lying LUMO with germylene pπ nature. We show the bond formation and activation alternatively at Au or Ge atom, a methylation of digoldgermane 3a with MeOTf affords methylgermane 5. Moreover, the digoldgermane 3a reacts with Cl− ion of Ph4PCl and CH3C(O)Cl smoothly to form the corresponding chloride-addition product 7 and chlorogoldgermane 9, respectively. Cyclic trimerization reactions of aromatic isocyanates were high-efficiently catalyzed by 3a giving the corresponding 1,3,5-triaryl isocyanurates.

Tandem C–O and C–H Activation at Palladium Enables Catalytic Direct C–H Alkenylation with Enol Pivalates

The use of oxygen-based electrophiles in cross-coupling remains challenging for substrates with strong C–O bonds, with few examples that can combine C–O activation with an-other strong-bond activation in tandem. We report the first example of a direct, tandem C–O/C–H activation approach to C–C bond formation using palladium catalysis. This reaction combines C–O oxidative addition at enol pivalates with con-certed metallation deprotonation of functionalized heterocycles to achieve base-free direct C–H alkenylation, with pivalic acid as the only byproduct. Mechanistic studies reveal that the Pd(II) C–O oxidative addition product is the major catalyst resting state, indicating that C–H activation is the turnover-limiting step.

The influence of the importance of cost information, product diversity and accountants’ participation on the activity-based costing adoption

Purpose The purpose of this study is twofold. The first objective is to examine the impact of the importance of cost information and product diversity on the adoption of activity-based costing (ABC) by Kazakhstani poultry organizations. The second goal is to establish the moderating impact of accountants’ involvement in the design for the costing system on the relationship between product diversity and the adoption of the ABC system. Design/methodology/approach The questionnaire was sent to all 58 poultry organizations in Kazakhstan and eventually, 43 completed questionnaires were collected, which is 74% of all Kazakhstani poultry organizations. Findings The results show that there is indeed a positive relationship between product diversity and ABC adoption when the level of diversity is used concurrently with accountants’ involvement in the design of product costing. In addition, product diversity was identified as a significant negative predictor of ABC adoption. Originality/value This study updates the literature on the rate of ABC adoption in a developing country like Kazakhstan, more specifically, in the poultry industry. It complements the understanding of the factors that influence the ABC adoption by taking a synergistic approach to factors such as product diversity and accountant involvement. At the same time, this study is one of the first empirical attempts to test the moderative role of the participation of accountants in the development of calculation systems in the ABC adoption.

Comparative analysis of biological versus chemical synthesis of palladium nanoparticles for catalysis of chromium (VI) reduction

The discharge of hexavalent chromium [Cr(VI)] from several anthropogenic activities leads to environmental pollution. In this study, we explore a simple yet cost effective method for the synthesis of palladium (Pd) nanoparticles for the treatment of Cr(VI). The presence of elemental Pd [Pd(0)] was confirmed by scanning electron microscope (SEM), electron dispersive spectroscopy and X-ray diffraction (XRD). We show here that the biologically synthesized nanoparticles (Bio-PdNPs) exhibit improved catalytic reduction of Cr(VI) due to their size being smaller and also being highly dispersed as compared to chemically synthesized nanoparticles (Chem-PdNPs). The Langmuir–Hinshelwood mechanism was successfully used to model the kinetics. Using this model, the Bio-PdNPs were shown to perform better than Chem-PdNPs due to the rate constant (kbio = 6.37 mmol s−1 m−2) and Cr(VI) adsorption constant (KCr(VI),bio = 3.11 × 10−2 L mmol−1) of Bio-PdNPs being higher than the rate constant (kchem = 3.83 mmol s−1 m−2) and Cr(VI) adsorption constant (KCr(VI),chem = 1.14 × 10−2 L mmol−1) of Chem-PdNPs. In addition, product inhibition by trivalent chromium [Cr(III)] was high in Chem-PdNPs as indicated by the high adsorption constant of Cr(III) in Chem-PdNPs of KCr(III),chem = 52.9 L mmol−1 as compared to the one for Bio-PdNPs of KCr(III),bio = 2.76 L mmol−1.