Recent advances in organic pressure-responsive luminescent materials

Organic luminescent materials are very sensitive to external stimuli,such as pressure,temperature,and electric field.The luminescent properties of some organic luminescent materials significantly change under high pressure.Some materials may show luminescence discoloration,whereas some may exhibit luminescence enhancement.These properties have many potential applications in anticounterfeiting,force sensor,data recording and storage,and luminescent devices,thereby greatly attracting the attention of scientists.In this review,the progress of research on these materials at high pressure in recent years is summarized.     

Recent developments in the enantioselective synthesis of polyfunctionalized pyran and chromene derivatives

Recent developments in the synthesis of 4H- and 2H-pyrans as well as structurally related chromene derivatives that have enabled the enantioselective synthesis of these scaffolds have been surveyed. The role of chiral catalysts in orienting initial reactions of active methylenes, methines and methyl ketones, to unsaturated ketones and nitriles in multi-component reactions or Friedel–Craft alkylations of phenols is discussed to show their involvement in transition states leading to end products. Chromene synthesis via [4+2] cycloadditions, [3+3] and [4+2] annulations as well as ring opening and recyclization leading to high enantio- and diasteroselectivity is also demonstrated. The enantioselectivity in such catalytic asymmetric reactions despite starting with non-chiral starting materials is discussed. On the other hand, in surveying ring opening and recyclization, the starting materials are chiral and the chiral center was not part of the reaction leading to the final product.     

Recent advances in Gomberg-Backmann biaryl synthesis

The Gomberg-Bachmann reaction is an intermolecular aryl-aryl cross-coupling reaction using an arenediazonium salt and an arene. This digest review surveys recent advances in the Gomberg-Bachmann reaction. More specifically, it focuses on reaction systems that include 1) transition-metal-induced systems, 2) organic promoter-induced systems, 3) electrolytic systems, 4) photoreaction systems, and 5) hybrid systems consisted of a photoredox and a transition-metal catalyst.     

Recent development in heavy paraffin synthesis from CO and H2

A review of recent studies on the Fischer–Tropsch synthesis of heavy paraffins is presented. The effects of temperature, pressure, feed composition, active metal, promoters and carriers on the formation of heavy products are discussed. New approaches to wax-selective processes such as the application of metallic carriers and supercritical fluids are also described.     

可见光促进的偕二氟烯烃制备与应用研究进展

偕二氟烯烃化合物在医药、材料、精细化工等领域具有广泛的应用,同时也是一类非常重要的用于制备各类复杂的有机氟化合物的有机合成中间体.可见光催化反应具有条件温和、绿色清洁等特点,已经成为有机化学中非常重要的合成手段之一.本文综述了近年来可见光促进的偕二氟烯烃化合物的制备及其在有机合成化学中的应用.     

New all-cis-tetra(p-tolyl)cyclotetrasiloxanetetraol and its functionalization

New all-cis-tetra(p-tolyl)cyclotetrasiloxanetetraol and its derivatives with Si(CH = CH₂)Me and Si(H)Me₂ groups have been prepared and characterized by IR and NMR spectroscopy, GPC, mass spectrometry, TGA and DSC. Molecular and crystalline structures of the tetraol and its derivative with four Si(CH = CH₂)Me groups have been determined by single-crystal X-ray diffraction.     

Regioselective functionalization of gem-bis(trifluoromethylated) alkanols

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CF3-Carbenoid functionalization of N-(pyrimidin-2-yl)indole catalyzed by cobalt complexes: Ligand control of selectivity

The carbonyl cobalt complex Cp*Co(CO)I₂ catalyzes carbenoid Co alkylation of N-(pyrimidin-2-yl)indole with methyl 3,3,3-trifluoro-2-diazopropionate regioselectively giving 2-substituted indole, while the N,N’-ligated cations [CpCo(L)I]⁺ (L = bipy, phen) provide 3-substitution exclusively. The structure of [CpCo(phen)I]PF₆ was investigated by X-ray diffraction.

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Recent advances in iron(III) chloride catalyzed synthesis of heterocycles

Heterocyclic compounds particularly five, six and seven membered ring containing heterocycles are the most abundant which constitute a staggeringly diverse and important class of molecules that occur ubiquitously in a variety of synthetic drugs, bioactive natural products, pharmaceuticals and agrochemicals. Owing to the glorious past and impressive present of the biologically active heterocyclic scaffolds, these skeletons have long been a subject of immense interest. Hence, substantial efforts have been made to the development of new and innovative synthetic strategies for the synthesis of these heterocycles involving use of different metal catalysts, organic and inorganic reagents etc. Among the different types of metal catalysts used, iron catalysts are one of the cheap and easily available. In recent time, several new and innovative iron(III) chloride catalyzed synthesis of heterocycles with structural diversity are coming in the forefront of the literature by the scientific community. This review highlights the advancements made so far by iron(III) chloride for the synthesis of different assemblies of small heterocycles covering the year 2014–2018.     

Double electrooxidative C–H functionalization of (het)arenes with thiocyanate and 4-nitropyrazolate ions

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Organocatalytic strategy for hydrophenolation of gem-difluoroalkenes

Gem-difluoroalkenes are an easily accessed fluorinated functional group, and a useful intermediate for elaborating into more complex fluorinated compounds. Currently, most functionalization reactions of gem-difluoroalkenes, with or without a transition metal-based catalyst system, involve the addition or removal of a fluorine atom to generate trifluorinated or monofluorinated products, respectively. In contrast, we present a complementary “fluorine-retentive” reaction that exploits an organocatalytic strategy to add phenols across gem-difluoroalkenes to deliver β,β-difluorophenethyl arylethers. The products are produced in good to moderate yields and selectivities, thus providing a range of compounds that are underrepresented in the synthetic and medicinal chemistry literature.     

Inverse electron demand Diels–Alder reaction as a novel method for functionalization of natural chlorins

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Recent advances in the synthesis and functionalization of 1,2,5-oxadiazole 2-oxides

Among the variety of nitrogen heterocycles, the furoxan (1,2,5-oxadiazole 2-oxide) scaffold has attracted considerable attention owing to its ability to release NO under physiological conditions. Therefore, significant efforts of organic chemists have been directed toward the construction of new drug candidates containing the NO-donor furoxan subunit connected to a known pharmaceutical or a potential pharmacophore by CC/CN bonds or through an appropriate linker. This digest summarizes the recent information concerning both new synthetic approaches for the furoxan ring construction and various methods for the functionalized furoxan synthesis with particular focus on the last three years. Methods for the furoxan ring formation including cyclodimerization of nitrile oxides, nitrosation of unsaturated compounds, and acylation of dinitromethane sodium salt are reviewed. The functionalization of furoxan ring is represented by nucleophilic substitution of nitro and arylsulfonyl groups as well as by different condensations of cyano-, carbonyl- and carboxyfuroxan derivatives. Synthesis of hybrid structures combining NO-donor furoxan ring and some pharmacophoric moiety is also considered.     

Applications of sharpless asymmetric dihydroxylation in the total synthesis of natural products

Sharpless asymmetric dihydroxylation involves the reaction of an alkene with osmium tetroxide in the presence of a chiral quinine ligand to form an optically active vicinal diol. This reaction was primarily developed by Sharpless based on the already known racemic Upjohn dihydroxylation. The chiral diols obtained by Sharpless asymmetric dihydroxylation are important intermediates in organic synthesis. Herein, we emphasise the applications of Sharpless asymmetric dihydroxylation in the total synthesis of natural products.     

New regiocontrolled syntheses of pyrrolopyrazinones and its application to the synthesis of peramine

Two novel regiocontrolled syntheses of pyrrolopyrazinones were developed. N-Methylpyrrole amide and 1-bromo-1-alkyne were annulated in the presence of a copper catalyst to give 3-substituted pyrrolopyrazinone in a regioselective manner. In contrast, heating N-methylpyrrole amide with the same haloalkyne in the presence of K₃PO₄ provided the haloaminal, which was transformed regioselectively into 4-substituted pyrrolopyrazinone. The former procedure was successfully applied to the synthesis of peramine, a natural product isolated from an endophytic fungus.     

Recent topics of gold catalyst featuring Z-type ligands

In the long history regarding the development of the transition metal-catalyzed reactions, almost all ligands in metals are classified as the covalent X-type and/or dative L-type ligands. Therefore, exploring the reactivity of the metal complexes bearing the σ-acceptor, i.e., the Z-ligand, is required. This digest briefly describes our recent results regarding 1) the syntheses of gold complexes featuring the Z-type ligand, and 2) their catalytic reactions, which would be speculated that the electron-withdrawing effect of the Z-ligand on the neighboring gold activated the catalytic reactivity due to the increase in the Lewis acidity.     

Recent advances in C(sp3)H bond carbonylation by first row transition metals

Carbonylation is one of the most valuable processes both in academia and industry. Direct functionalization of inert C(sp²)H bond into C(sp²)-carbonyl derivatives was actively pursued over decades using noble metals. But the corresponding C(sp³)H bond carbonylation is a challenging area and only few examples were known till now. Utilization of first row transition metals as an alternative to their noble partners is more sustainable. In this context, use of first row transition metals for direct C(sp³)H bond functionalization is burgeoning as an exciting area. This digest review covers some of the recent achievements in this regard especially using Ni, Co and Cu as first row transition metals. The reported approaches are categorized in two types: directed and non-directed activation/functionalization of C(sp³)H bonds using carbon monoxide gas or its surrogates as a C1 source.     

A highly stereoselective and efficient synthesis of enantiomerically pure sitagliptin

A highly stereoselective and efficient synthesis of sitagliptin 1 consisting of a chiral β-amino acid unit has been achieved through 6 steps from commercially available 2,4,5-trifluorobenzaldehyde 4. The chiral antidiabetic drug was obtained with almost perfect enantiomeric purity (>99.9% ee) in 40.9% overall yield. The key feature of the synthesis is the addition of a malonate enolate to a chiral sulfinylimine in more than 99:1 dr. Our synthetic procedure proved to be highly efficient, economical, and sustainable.     

The first synthesis of 7-prenylisatin

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