•Plant flavonoids are important natural bioactive compounds.•Flavonoid classification and plants rich in flavonoids are summarized.•Flavonoid functions in biological processes in plants are ...reviewed.•Transcription factors regulate the biosynthesis of plant flavonoids.•Epidemic evidence, in vitro and in vivo studies reveal flavonoid bioactivity.
Flavonoids are a group of natural polyphenol substances abundant in vegetables, fruits, grains, and tea. As plant secondary metabolites, flavonoids play essential roles in many biological processes and responses to environmental factors in plants. Flavonoids are common in human diets and have antioxidant effects as well as other bioactivities (e.g., antimicrobial and anti-inflammatory properties), which reduce the risk of disease. Flavonoid bioactivity depends on structural substitution patterns in their C6-C3-C6 rings. However, reviews of plant flavonoid distribution and biosynthesis, as well as the health benefits of its bioactivity, remain scarce. Therefore, in the present review, we systematically summarize recent progress in the research of plant flavonoids, focusing on their biosynthesis (pathway and transcription factors) and bioactive mechanisms based on epidemic evidence, in vitro and in vivo research, and bioavailability in the human body. We also discuss future opportunities in flavonoid research, including biotechnology, therapeutic phytoproducts, and dietary flavonoids.
Electronically matched nucleophilic 1,6‐conjugate addition has been well studied and widely applied in synthetic areas. In contrast, nucleophilic 1,5‐conjugate addition represents an electronically ...forbidden process and is considered unfeasible. Here, we describe modular protocols for 1,5‐conjugate addition reactions via palladium hydride catalysis. Both palladium and synergistic Pd/organocatalyst systems are developed to catalyze 1,5‐conjugate reaction, followed by inter‐ or intramolecular 3+2 cyclization. A migratory 1,5‐addition protocol is established to corroborate the feasibility of this umpolung concept. The 1,5‐addition products are conveniently transformed into a series of privileged enantioenriched motifs, including polysubstituted tetrahydrofuran, dihydrofuran, cyclopropane, cyclobutane, azetidine, oxetane, thietane, spirocycle and bridged rings. Preliminary mechanistic studies corroborate the involvement of palladium hydride catalysis.
An unconventional umpolung protocol was demonstrated for novel 1,5‐conjugate additions via palladium hydride catalyst. Three catalytic reaction modes including 1,5‐addition cascade with inter‐ and intramolecular 3+2 cyclization and migratory 1,5‐addition were established via palladium or palladium/organo‐cocatalysis.
In this work, by using
N
-methoxybenzamides as efficient acyl nitrene precursors, an iron-catalyzed formal
cis
-haloamidation of alkyne is reported. Without assistance of additives, the reaction ...worked well in the presence of 50 mol% FeCl
3
or FeBr
3
, leading to a series of chloro/bromo-containing isoindolin-5-ones with high efficiency and wide reaction scope. In the reaction, the iron-facilitated haloamidation proceeds through a halo anion-participating concerted 3+2 cyclization to release the final products. The key intermediate ferric acyl nitrene
A
is generated
in situ
from a formal removal of MeOH.
In this work, by using
N
-methoxybenzamides as efficient acyl nitrene precursors, an iron-catalyzed acyl nitrene/alkyne metalation-based chloramidation is reported for the synthesis of isoindol-5-ones.
Biomineralization is an important tactic by which biological organisms produce hierarchically structured minerals with marvellous functions. Biomineralization studies typically focus on the mediation ...function of organic matrices on inorganic minerals, which helps scientists to design and synthesize bioinspired functional materials. However, the presence of inorganic minerals may also alter the native behaviours of organic matrices and even biological organisms. This progress report discusses the latest achievements relating to biomineralization mechanisms, the manufacturing of biomimetic materials and relevant applications in biological and biomedical fields. In particular, biomineralized vaccines and algae with improved thermostability and photosynthesis, respectively, demonstrate that biomineralization is a strategy for organism evolution via the rational design of organism‐material complexes. The successful modification of biological systems using materials is based on the regulatory effect of inorganic materials on organic organisms, which is another aspect of biomineralization control. Unlike previous studies, this study integrates materials and biological science to achieve a more comprehensive view of the mechanisms and applications of biomineralization.
Biomineralization studies focus on the mediation function of organic matrices on inorganic minerals, which helps scientists to design and sythesize bioinspired functional materials. At the same time, the modification of biological systems using materials is based on the regulatory effect of inorganic materials on organic organisms, which is the aspect of biomineralization control.
Nitroarenes are used as the coupling partners in the preparation of sulfonamides via the insertion of sulfur dioxide. A three-component reaction of arylboronic acids, nitroarenes, and potassium ...metabisulfite under copper catalysis proceeds smoothly, giving rise to a range of sulfonamides in good to excellent yields with broad substrate scope. Various functional groups including hydroxyl, cyano, amino, and carbonyl are all tolerated. A plausible mechanism is proposed, showing that arylsulfinate is the intermediate and the copper-assisted interaction of the nitroarene and arylsulfinate is the key step. This approach is also extended to the late-stage modification of a currently marketed drug (flutamide).
Summary of main observation and conclusion
Sulfonylation of alkenes through photoredox‐catalyzed functionalization of alkenes with thiourea dioxide under visible‐light irradiation is achieved. The ...reaction of alkenes, thiourea dioxide and electrophiles provides a green and efficient access to alkyl sulfones and sulfonamides. A broad reaction scope is presented with good functional group compatibility and excellent regioselectivity. A plausible mechanism involving a radical addition process with sulfur dioxide radical anion (SO2‐) derived from the oxidation of sulfur dioxide anion (SO22–) is proposed, which is supported by fluorescence quenching experiments.
Nucleation, the early stage of crystallization, is a key step in producing functional materials, but nucleation processes have yet to be understood in detail. Recent advanced characterization ...techniques, especially atomic force microscopy, liquid-cell transmission electron microscopy (TEM) and cryo-TEM, enable scientists to observe previously inaccessible nucleation details at the nanoscale. In this review, we summarize newly suggested non-classical nucleation models with respect to mechanistic understanding from experimental views, which highlight multi-step nucleation mechanisms. Different intermediated phases such as clusters at the pre-nucleation stage, liquid-like precursors, amorphous phases and even oligomers have been revealed, which play vital roles in nucleation and structure control. Moreover, these intermediated phases practically contribute in general to the structural variances of materials for nanoscience and nanotechnology. Overall, these studies ultimately enable us to control nucleation processes for materials synthesis.
This work provides a clearer picture for non-classical nucleation by revealing the presence of various intermediates using advanced characterization techniques.
A metal-free route to alkynyl sulfones under photoinduced conditions is accomplished, starting from 4-alkyl Hantzsch esters, sulfur dioxide, and alkynyl bromides under visible light irradiation at ...room temperature. This transformation proceeds smoothly, affording the corresponding alkylalkynyl sulfones in moderate to good yields by using sodium metabisulfite as the sulfur dioxide surrogate. A plausible mechanism is proposed, showing that the alkyl radical generated
in situ
from 4-alkyl Hantzsch esters in the presence of a photocatalyst initiates the reaction. Subsequent sulfonylation, addition to alkynyl bromide, and release of bromide give rise to the corresponding alkylalkynyl sulfone.
A metal-free route to alkynyl sulfones under photoinduced conditions is accomplished, starting from 4-alkyl Hantzsch esters, sulfur dioxide, and alkynyl bromides under visible light irradiation at room temperature.
Metal-free insertion of sulfur dioxide with aryl iodides and 3-azido-2-methylbut-3-en-2-ol under ultraviolet irradiation at room temperature is achieved, giving rise to 2-(arylsulfonyl)acetonitriles ...in moderate to good yields. Alkyl iodide is also workable under these conditions. This transformation proceeds smoothly under mild conditions with a broad substrate scope. Various functional groups are compatible including amino, ester, halo, and trifluoromethyl groups. No metal catalyst or additive is needed during the reaction process. Mechanistic studies show that under ultraviolet irradiation, an aryl radical is generated
in situ
from aryl iodide, which undergoes subsequent sulfonylation
via
the insertion of sulfur dioxide leading to arylsulfonyl radical intermediates. Then the arylsulfonyl radical reacts with 3-azido-2-methylbut-3-en-2-ol giving rise to the corresponding 2-(arylsulfonyl)acetonitrile.
Metal-free insertion of sulfur dioxide with aryl/alkyl iodides and 3-azido-2-methylbut-3-en-2-ol under ultraviolet irradiation at room temperature is achieved, giving rise to 2-sulfonylacetonitriles in moderate to good yields.
