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We herein report that the highly hydrophobic ether 4‐MeTHP constitutes a promising resource for the development of sustainable synthetic methodologies grounded on the use of organometallic reagents. The beneficial effects of 4‐MeTHP as reaction medium are illustrated in the organolithium‐promoted anionic ortho‐Fries rearrangement of 1,1'‐bi‐2‐naphthol (BINOL)‐based carbamates under bench‐type conditions. The use of 4‐MeTHP induces a remarkable and unexpected stability of the organolithiums species, enabling the efficient preparation of chiral (bis)carboxamide catalysts. Furthermore, superior performances of 4‐MeTHP than other environmentally responsible solvents are observed using the synthesized BINOL catalysts in the asymmetric addition of organozinc reagents to aldehydes. Spectroscopic studies in solution suggest that 4‐MeTHP plays a key role in these reactions by inducing the preferential formation of a reactive monomeric dinuclear complex. This methodology allows for the asymmetric assembly of enantioenriched secondary alcohols in good yields and high stereoselectivity, working at 0 °C and under air. [ABSTRACT FROM AUTHOR]

The first enantioselective reduction of 2‐substituted cyclic imines to the corresponding amines (pyrrolidines, piperidines, and azepines) by imine reductases (IREDs) in non‐conventional solvents is reported. The best results were obtained in a glycerol/phosphate buffer 1 : 1 mixture, in which heterocyclic amines were produced with full conversions (>99 %), moderate to good yields (22–84 %) and excellent S‐enantioselectivities (up to >99 % ee). Remarkably, the process can be performed at a 100 mM substrate loading, which, for the model compound, means a concentration of 14.5 g L−1. A fed‐batch protocol was also developed for a convenient scale‐up transformation, and one millimole of substrate 1 a was readily converted into 120 mg of enantiopure amine (S)‐2 a with a remarkable 80 % overall yield. This aspect strongly contributes to making the process potentially attractive for large‐scale applications in terms of economic and environmental sustainability for a good number of substrates used to produce enantiopure cyclic amines of high pharmaceutical interest. [ABSTRACT FROM AUTHOR]

The rise of drug resistance to antivirals poses a significant global concern for public health; therefore, there is a pressing need to identify novel compounds that can effectively counteract strains resistant to current antiviral treatments. In light of this, researchers have been exploring new approaches, including the investigation of natural compounds as alternative sources for developing potent antiviral therapies. Thus, this work aimed to evaluate the antiviral properties of the organic-soluble fraction of a root exudate derived from the tomato plant Solanum lycopersicum in the context of herpesvirus infections. Our findings demonstrated that a root exudate from Solanum lycopersicum exhibits remarkable efficacy against prominent members of the family Herpesviridae, specifically herpes simplex virus type 1 (HSV-1) (EC50 25.57 µg/mL, SI > 15.64) and human cytomegalovirus (HCMV) (EC50 9.17 µg/mL, SI 32.28) by inhibiting a molecular event during the herpesvirus replication phase. Moreover, the phytochemical fingerprint of the Solanum lycopersicum root exudate was characterized through mass spectrometry. Overall, these data have unveiled a novel natural product with antiherpetic activity, presenting a promising and valuable alternative to existing drugs. [ABSTRACT FROM AUTHOR]

The synthesis of acetals in acidic natural deep eutectic solvents (NADES), in which the solvent itself participates in the catalytic promotion of the reaction, is reported herein. The reaction is performed under feasible conditions, open air, without the need of external additives, catalysts or water‐removing techniques, and it is wide in scope. The products are easily recovered, and the reaction medium is fully recycled and reused without weakening of its catalytic activity after 10 times. Remarkably, the entire process has been realized on gram scale. [ABSTRACT FROM AUTHOR]

A straightforward protocol to promote the tetrahydropyranylation of alcohols, using for the first time bioinspired acidic natural deep eutectic solvents (NADESs) as non‐innocent reaction media under mild reaction conditions, was reported. This approach enables the preparation of several tetrahydropyranyl (THP) ethers starting from primary, secondary and tertiary alcohols in short reaction times and with high levels of chemoselectivity, working under air and without the need of additional catalyst. The sustainability of the methodology was further highlighted by its scalability and the easy recyclability of the NADES, allowing multigram preparations of THP ethers without any loss of the catalytic activity of the reaction media up to ten recycling steps. Telescoped, one‐pot tetrahydropyranylation/nucleophilic acyl substitution transformations using the same eutectic mixture were also demonstrated. [ABSTRACT FROM AUTHOR]

During the last decade, a wide spectrum of applications and advantages in the use of deep eutectic solvents for promoting organic reactions has been well established among the scientific community. Among these synthetic methodologies, in recent years, various examples of biocatalyzed processes have been reported, making use of eutectic mixtures as reaction media, as an improvement in terms of selectivity and sustainability. This review aims to show the newly reported protocols in the field, subdivided by reaction class as a 'toolbox' guide for organic synthesis. [ABSTRACT FROM AUTHOR]

A straightforward and efficient protocol to promote the metalation/anionic Fries rearrangements of O‐aryl carbamates, using for the first time a lithium amide as metalating agent under aerobic/ambient‐friendly reaction conditions, is reported. This approach enables the sustainable preparation of salicylamide derivatives with high levels of chemoselectivity within ultrafast reaction times, working at room temperature in the presence of air/moisture, and using environmentally responsible cyclopentyl methyl ether as a solvent. Furthermore, the regioselective manipulation of O‐2‐tolyl carbamates has been accomplished using interchangeably alkyllithiums or lithium amides, with an unexpected beneficial contribution from the employment of biorenewable protic eutectic mixtures as non‐innocent reaction media. [ABSTRACT FROM AUTHOR]

Summary: Strigolactones (SLs) are plant hormones and important signalling molecules required to promote arbuscular mycorrhizal (AM) symbiosis. While in plants an α/β‐hydrolase, DWARF14 (D14), was shown to act as a receptor that binds and cleaves SLs, the fungal receptor for SLs is unknown.Since AM fungi are currently not genetically tractable, in this study, we used the fungal pathogen Cryphonectria parasitica, for which gene deletion protocols exist, as a model, as we have previously shown that it responds to SLs. By means of computational, biochemical and genetic analyses, we identified a D14 structural homologue, CpD14.Molecular homology modelling and docking support the prediction that CpD14 interacts with and hydrolyses SLs. The recombinant CpD14 protein shows α/β hydrolytic activity in vitro against the SLs synthetic analogue GR24; its enzymatic activity requires an intact Ser/His/Asp catalytic triad. CpD14 expression in the d14‐1 loss‐of‐function Arabidopsis thaliana line did not rescue the plant mutant phenotype. However, gene inactivation by knockout homologous recombination reduced fungal sensitivity to SLs.These results indicate that CpD14 is involved in SLs responses in C. parasitica and strengthen the role of SLs as multifunctional molecules acting in plant–microbe interactions. [ABSTRACT FROM AUTHOR]

Strigolactones are a class of carotenoid‐derived plant hormones, which impact many functions of plant metabolism in response to environmental stress. They also act as exogenous signals perceived by both mycorrhizal fungi and parasitic plants. The peculiar chemical skeleton of these molecules and their mode of action in plants inspired possible applications in biomedical fields. In this minireview, an overview of the most recent applications of Strigolactones and analog derivatives as anticancer, anti‐inflammatory, and antiviral drugs is described. [ABSTRACT FROM AUTHOR]

This review summarizes the advances made on the synthesis and functionalization of furans via gold catalysis during the period between 2016 and 2020. A separate section is dedicated to the tandem gold-catalyzed synthesis and functionalization of furans. 1 Introduction 2 Gold-Catalyzed Synthesis of Furans 2.1 Cycloisomerizations of Alkynyl and Cumulenyl Alcohols 2.2 Cycloisomerizations of Alkynyl and Allenyl Ketones 2.3 Reactions with External Oxidants 2.4 Miscellaneous 3 Gold-Catalyzed Functionalization of Furans 3.1 Cycloadditions 3.2 Furan Ring Decorations 3.3 Reactions Involving Furan Ring Opening 4 Gold-Catalyzed Tandem Synthesis and Functionalization of Furans- 4.1 Cycloisomerizations Followed by Gold-Catalyzed Cycloaddition 4.2 Cycloisomerizations to a Gold 1,3- or 1,4-Dipole and Intermolecular Annulation 4.3 Cycloisomerizations to a Gold Carbene and Intermolecular Trapping 5 Conclusion [ABSTRACT FROM AUTHOR]

Short chain chitooligosaccharides (COs) are chitin derivative molecules involved in plant-fungus signaling during arbuscular mycorrhizal (AM) interactions. In host plants, COs activate a symbiotic signalling pathway that regulates AM-related gene expression. Furthermore, exogenous CO application was shown to promote AM establishment, with a major interest for agricultural applications of AM fungi as biofertilizers. Currently, the main source of commercial COs is from the shrimp processing industry, but purification costs and environmental concerns limit the convenience of this approach. In an attempt to find a low cost and low impact alternative, this work aimed to isolate, characterize and test the bioactivity of COs from selected strains of phylogenetically distant filamentous fungi: Pleurotus ostreatus, Cunninghamella bertholletiae and Trichoderma viride. Our optimized protocol successfully isolated short chain COs from lyophilized fungal biomass. Fungal COs were more acetylated and displayed a higher biological activity compared to shrimp-derived COs, a feature that—alongside low production costs—opens promising perspectives for the large scale use of COs in agriculture. [ABSTRACT FROM AUTHOR]

We report that the nucleophilic acyl substitution reaction of aliphatic and (hetero)aromatic amides by organolithium reagents proceeds quickly (20 s reaction time), efficiently, and chemoselectively with a broad substrate scope in the environmentally responsible cyclopentyl methyl ether, at ambient temperature and under air, to provide ketones in up to 93 % yield with an effective suppression of the notorious over‐addition reaction. Detailed DFT calculations and NMR investigations support the experimental results. The described methodology was proven to be amenable to scale‐up and recyclability protocols. Contrasting classical procedures carried out under inert atmospheres, this work lays the foundation for a profound paradigm shift of the reactivity of carboxylic acid amides with organolithiums, with ketones being straightforwardly obtained by simply combining the reagents under aerobic conditions and with no need of using previously modified or pre‐activated amides, as recommended. [ABSTRACT FROM AUTHOR]

The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation–metalation–acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β‐diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the structural analysis gathers key aspects of this class of valuable ligands in catalysis. [ABSTRACT FROM AUTHOR]

The selective formal insertion (homologation) of a carbon unit bridging the two trifluoroacetamidoyl chlorides (TFAICs) units is reported. The tactic is levered on a highly chemoselective homologation–metalation–acyl nucleophilic substitution sequence which precisely enables to assemble novel trifluoromethylated β‐diketiminates within a single synthetic operation. Unlike previous homologations conducted with LiCH2Cl furnishing aziridines, herein we exploit the unique capability of iodomethyllithium to act contemporaneously as a C1 source (homologating effect) and metalating agent. The mechanistic rationale grounded on experimental evidences supports the hypothesized proposal and, the structural analysis gathers key aspects of this class of valuable ligands in catalysis. [ABSTRACT FROM AUTHOR]

The heteroatom-directed lateral lithiation of functionalized toluenes in a choline chloride-based eutectic mixture is reported. The metalations proceed within ultrafast reaction times, with a broad substrate and electrophile scope. The directing groups provide a rapid and high regioselective access to functionalized aromatic derivatives of remarkable synthetic value. [ABSTRACT FROM AUTHOR]

The gold(I)‐catalysed cyclization of N‐tosyl‐protected 5‐benzyl‐6‐((trimethylsilyl)ethynyl)‐1,2,3,4‐tetrahydropyridines, prepared by the Sonogashira coupling of lactam‐derived enol triflates, provides tetrahydrobenzo[g]quinolines whose skeleton represents a recurrent motif in natural compounds. The Au(I)‐catalysed reaction is carried out with (C6F5)3PAuCl/AgNTf2 as the catalyst system and proceeds via a 6‐exo‐dig cyclization to form an exocyclic double bond, which eventually isomerises to the aromatic tetrahydrobenzo[g]quinoline. The mode of cyclization is discussed and supported by DFT calculations. [ABSTRACT FROM AUTHOR]

Natural deep eutectic solvents have emerged as alternative non-toxic, non-aqueous solvents for an increasing number of synthetic transformations. Remarkably, in some cases one (or more) components of the NaDES plays an active role in the reaction mechanism and directly participates as either a catalyst or a reagent in the reaction. In this paper, we tested several NaDESs in which one of the components is a carboxylic acid as a medium to perform the Nazarov cyclization of divinyl ketones to obtain cyclopentenones, a widespread motif in natural compounds. The reaction conditions were optimized and the scope was investigated on C-, O- and N-derived compounds. To assess the full sustainability of the proposed approach, the recyclability and scalability of the process were investigated, thus proving that multi-gram preparations are possible with complete recycling of the medium. [ABSTRACT FROM AUTHOR]

Natural products containing a N‐heterocycle motif are widespread in nature and medicinal plants, in particular, have proved to be a source of almost unlimited N‐derived structures with high molecular diversity. Because of their intrinsic potential for use in both biomedical and agricultural applications, there is a general need for new compounds and for the synthesis of 'natural‐inspired' analogues. Importantly, transition of a natural product from discovery to a 'market lead' is associated with an increasingly challenging demand for more of the compound, which cannot be met by isolation from natural plant sources, often due to low extraction yields and uneven availability of the plant source itself. Synthesis remains the most reliable approach to provide valuable products for the market. In this review, a comprehensive overview of our contribution to synthetic access to N‐derived natural products is given. Major strengths of the proposed methodologies are discussed critically. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Directed ortho metalation (DoM) or nucleophilic acyl substitution (SNAc) can be efficiently programmed on the same aromatic carboxylic acid amide, in a choline chloride-based eutectic mixture, by simply switching the nature of the organolithium reagent. Telescoped, one-pot ortho-lithiation/Suzuki–Miyaura cross-couplings have also been demonstrated for the first time in Deep Eutectic Solvents. [ABSTRACT FROM AUTHOR]

A small library of carborane‐BODIPY/aza‐BODIPY dyads were efficiently synthesized by means of a novel convergent synthetic approach, the key step of which is a Pd‐catalyzed Heck coupling reaction. The structural characterization and photoluminescence properties of the newly synthesized dyads were evaluated. The presence of the carborane did not significantly alter the photophysical patterns of the BODIPY or aza‐BODIPY in the final fluorophores, but it produced a decrease of the emission fluorescent quantum yields that was in the range from 1.4 % for aza‐BODIPY to 48 % for BODIPY‐dyads. The carborane‐BODIPY dyads were successfully incorporated into cells, especially compounds 2, 4 and 13, demonstrating their cytoplasmic localization. The fluorescent and biocompatibility properties make these compounds good candidates for in vitro cell tracking. The efficient Pd‐catalyzed Heck coupling reaction between BODIPY, aza‐DIPYs and styrenyl carboranes leads to a small library of carborane‐BODIPY/aza‐BODIPY dyads. Their fluorescence properties and internalization by HeLa cells make these compounds good candidates for in vitro cell tracking. [ABSTRACT FROM AUTHOR]

Cannabis sativa active compounds are extensively studied for their therapeutic effects, beyond the well-known psychotropic activity. C. Sativa is used to treat different medical indications, such as multiple sclerosis, spasticity, epilepsy, ulcerative colitis and pain. Simultaneously, basic research is discovering new constituents of cannabis-derived compounds and their receptors capable of neuroprotection and neuronal activity modulation. The function of the various phytochemicals in different therapeutic processes is not fully understood, but their significant role is starting to emerge and be appreciated. In this review, we will consider the structure-activity relationship (SAR) of cannabinoid compounds able to bind to cannabinoid receptors and act as therapeutic agents in neuronal diseases, e.g., Parkinson’s disease. [ABSTRACT FROM AUTHOR]

Strigolactones (SLs) are plant hormones with various functions in development, responses to stress, and interactions with (micro)organisms in the rhizosphere, including with seeds of parasitic plants. Their perception for hormonal functions requires an α,β-hydrolase belonging to the D14 clade in higher plants; perception of host-produced SLs by parasitic seeds relies on similar but phylogenetically distinct proteins (D14-like). D14 and D14-like proteins are peculiar receptors, because they cleave SLs before undergoing a conformational change that elicits downstream events. Structure--activity relationship data show that the butenolide D-ring is crucial for bioactivity. We applied a bioisosteric approach to the structure of SLs by synthetizing analogues and mimics of natural SLs in which the D-ring was changed from a butenolide to a lactam and then evaluating their bioactivity. This was done by using a novel bioassay based on Arabidopsis transgenic lines expressing AtD14 fused to firefly luciferase, in parallel with the quantification of germination-inducing activity on parasitic seeds. The results obtained showed that the in planta bioassay is robust and quantitative, and thus can be confidently added to the SL-survey toolbox. The results also showed that modification of the butenolide ring into a lactam one significantly hampers the biological activity exhibited by SLs possessing a canonical lactonic D-ring. [ABSTRACT FROM AUTHOR]

Strigolactones, a group of terpenoid lactones, control many aspects of plant growth and development, but the active forms of these plant hormones and their mode of action at the molecular level are still unknown. The strigolactone protein receptor is unusual because it has been shown to cleave the hormone and supposedly forms a covalent bond with the cleaved hormone fragment. This interaction is suggested to induce a conformational change in the receptor that primes it for subsequent interaction with partners in the signalling pathway. Substantial efforts have been invested into describing the interaction of synthetic strigolactone analogues with the receptor, resulting in a number of crystal structures. This investigation combines a re-evaluation of models in the Protein Data Bank with a search for new conditions that may permit the capture of a receptor--ligand complex. While weak difference density is frequently observed in the binding cavity, possibly due to a low-occupancy compound, the models often contain features not supported by the X-ray data. Thus, at this stage, we do not believe that any detailed deductions about the nature, conformation, or binding mode of the ligand can be made with any confidence. [ABSTRACT FROM AUTHOR]

Abstract: Palladium(0)‐catalysed hydro‐alkylation or ‐alkenylation of alkoxyallenes with N‐tosylhydrazones gives direct access to conjugated and skipped 1‐alkoxydienes with high efficiency and excellent functional‐group compatibility. The reaction is proposed to involve the in situ‐formed t‐butanol as proton source in the key step of the allylpalladium(II) species generation. Moreover, lithium iodide or iodobenzene are employed as an unprecedented iodide (I−) reservoir to sustain the catalytic cycle. [ABSTRACT FROM AUTHOR]

Strigolactones are a class of natural and synthetic compounds that in the past decade have been exciting the scientific community not only for their intriguing biological properties but also for their potential applications in agriculture. These applications range from their use as hormones to modify and/or manage plant architecture, to their use as stimulants to induce seed germination of parasitic weeds and thus control their infestation by a reduced seed bank, to their use as 'biostimulants' of plant root colonisation by arbuscular mycorrhizal fungi, improving plant nutritional capabilities, to other still unknown effects on microbial soil communities. More recently, these compounds have also been attracting the interest of agrochemical companies. In spite of their biological attractiveness, practical applications are still greatly hampered by the low product yields obtainable by plant root exudates, by the costs of their synthesis, by the lack of knowledge of their off-target effects and by the not yet specified or properly identified legislation that could regulate the use of these compounds, depending on the agricultural purposes. The aim of this article is to discuss, in the light of current knowledge, the different scenarios that might play out in the near future with regard to the practical application of strigolactones. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Modern biology overlaps with chemistry in explaining the structure and function of all cellular processes at the molecular level. Plant hormone research is perfectly located at the interface between these two disciplines, taking advantage of synthetic and computational chemistry as a tool to decipher the complex biological mechanisms regulating the action of plant hormones. These small signaling molecules regulate a wide range of developmental processes, adapting plant growth to ever changing environmental conditions. The synthesis of small bioactive molecules mimicking the activity of endogenous hormones allows us to unveil many molecular features of their functioning, giving rise to a new field, plant chemical biology. In this framework, fluorescence labeling of plant hormones is emerging as a successful strategy to track the fate of these challenging molecules inside living organisms. Thanks to the increasing availability of new fluorescent probes as well as advanced and innovative imaging technologies, we are now in a position to investigate many of the dynamic mechanisms through which plant hormones exert their action. Such a deep and detailed comprehension is mandatory for the development of new green technologies for practical applications. In this review, we summarize the results obtained so far concerning the fluorescent labeling of plant hormones, highlighting the basic steps leading to the design and synthesis of these compelling molecular tools and their applications. [ABSTRACT FROM AUTHOR]

Main conclusion: MAX2/strigolactone signaling in the endodermis and/or quiescent center of the root is partially sufficient to exert changes in F-actin density and cellular trafficking in the root epidermis, and alter gene expression during plant response to low Pi conditions. Strigolactones (SLs) are a new group of plant hormones that regulate different developmental processes in the plant via MAX2, an F-box protein that interacts with their receptor. SLs and MAX2 are necessary for the marked increase in root-hair (RH) density in seedlings under conditions of phosphate (Pi) deprivation. This marked elevation was associated with an active reduction in actin-filament density and endosomal movement in root epidermal cells. Also, expression of MAX2 under the SCARECROW ( SCR) promoter was sufficient to confer SL sensitivity in roots, suggesting that SL signaling pathways act through a root-specific, yet non-cell-autonomous regulatory mode of action. Here we show evidence for a non-cell autonomous signaling of SL/MAX2, originating from the root endodermis, and necessary for seedling response to conditions of Pi deprivation. SCR-derived expression of MAX2 in max2- 1 mutant background promoted the root low Pi response, whereas supplementation of the synthetic SL GR24 to these SCR:MAX2 expressing lines further enhanced this response. Moreover, the SCR:MAX2 expression led to changes in actin density and endosome movement in epidermal cells and in TIR1 and PHO2 gene expression. These results demonstrate that MAX2 signaling in the endodermis and/or quiescent center is partially sufficient to exert changes in F-actin density and cellular trafficking in the epidermis, and alter gene expression under low Pi conditions. [ABSTRACT FROM AUTHOR]

The article mentions the active regulation of Strigolactones involving their influx and efflux, also mentioning the cell-trafficking system.

The gold(I)-catalysed reaction of N-Boc-protected 6-alkynyl- 3,4-dihydro-2H-pyridines, which gives synthetically useful vinylogous amides (β-enaminones), has been studied in detail, in order to optimize the reaction conditions, enlarge the scope and gain insight into the mechanism and the structural features that selectively favour the 6-endo-dig oxyauration of the triple bond. Experimental studies and DFT calculations demonstrate that the 6-endo-dig approach is exclusive with substituted alkynes, whereas with terminal alkynes the 5- exo-dig cyclization prevails, despite the large angle (120°) at C-6. The same selectivity was observed with N-Cbz-protected 2-alkynylpiperidines. With these compounds, β-amino ketones are obtained as a consequence of the 6-endo-dig attack onto a substituted triple bond. Sedamine alkaloids are easily obtained by this approach. [ABSTRACT FROM AUTHOR]

The gold(I)-catalysed reaction of N-Boc-protected 6-alkynyl-3,4-dihydro-2 H-pyridines, which gives synthetically useful vinylogous amides (β-enaminones), has been studied in detail, in order to optimize the reaction conditions, enlarge the scope and gain insight into the mechanism and the structural features that selectively favour the 6- endo-dig oxyauration of the triple bond. Experimental studies and DFT calculations demonstrate that the 6- endo-dig approach is exclusive with substituted alkynes, whereas with terminal alkynes the 5- exo-dig cyclization prevails, despite the large angle (120°) at C-6. The same selectivity was observed with N-Cbz-protected 2-alkynylpiperidines. With these compounds, β-amino ketones are obtained as a consequence of the 6- endo-dig attack onto a substituted triple bond. Sedamine alkaloids are easily obtained by this approach. [ABSTRACT FROM AUTHOR]

This study provides an insight into the cellular events of cytoskeleton rearrangement, vesicle trafficking, and PIN protein localization that are associated with low-Pi response and are dependent on strigolactone-auxin cross-talk.Strigolactones (SLs) are plant hormones that regulate the plant response to phosphate (Pi) growth conditions. At least part of SL-signalling execution in roots involves MAX2-dependent effects on PIN2 polar localization in the plasma membrane (PM) and actin bundling and dynamics. We examined PIN2 expression, PIN2 PM localization, endosome trafficking, and actin bundling under low-Pi conditions: a MAX2-dependent reduction in PIN2 trafficking and polarization in the PM, reduced endosome trafficking, and increased actin-filament bundling were detected in root cells. The intracellular protein trafficking that is related to PIN proteins but unassociated with AUX1 PM localization was selectively inhibited. Exogenous supplementation of the synthetic SL GR24 to a SL-deficient mutant (max4) led to depletion of PIN2 from the PM under low-Pi conditions. Accordingly, roots of mutants in MAX2, MAX4, PIN2, TIR3, and ACTIN2 showed a reduced low-Pi response compared with the wild type, which could be restored by auxin (for all mutants) or GR24 (for all mutants except max2-1). Changes in PIN2 polarity, actin bundling, and vesicle trafficking may be involved in the response to low Pi in roots, dependent on SL/MAX2 signalling. [ABSTRACT FROM PUBLISHER]

A Mizoroki-Heck-heteroannulation cascade reaction has been used to prepare substituted dihydrobenzofurans and indolines in good yields by the reaction between functionalised alkoxy-1,3-dienes and several o-iodophenols or protected o-iodoanilines. [ABSTRACT FROM AUTHOR]

This article deals with the synthesis of fluorescent strigolactone analogs to be used as molecular probes in the detection of the receptor and the destiny of the molecules in the cells. A detailed description of the concept, design and synthesis, spectroscopic properties, and preliminary bioimaging applications is given.Originally identified as allelochemicals involved in plant–parasite interactions, more recently, Strigolactones (SLs) have been shown to play multiple key roles in the rhizosphere communication between plants and mycorrhizal fungi. Even more recent is the hormonal role ascribed to SLs which broadens the biological impact of these relatively simple molecules. In spite of the crucial and multifaceted biological role of SLs, there are no data on the receptor(s) which bind(s) such active molecules, neither in the producing plants nor in parasitic weeds or AM fungi. Information about the putative receptor of SLs can be gathered by means of structural, molecular, and genetic approaches. Our contribution on this topic is the design and synthesis of fluorescent labeled SL analogs to be used as probes for the detection in vivo of the receptor(s). Knowledge of the putative receptor structure will boost the research on analogs of the natural substrates as required for agricultural applications. [ABSTRACT FROM AUTHOR]

Synthetic strigolactone analogs were examined for their differential activity on Arabidopsis root-hair elongation, Orobanche seed germination, and Glomus hyphal branching. Variations in receptor(s) sensitivity between the examined systems were found and structure–function relations of the strigolactone analogs were proposed.Strigolactones (SLs) have several functions as signaling molecules in their interactions with symbiotic arbuscular mycorrhizal (AM) fungi and the parasitic weeds Orobanche and Striga. SLs are also a new class of plant hormone regulating plant development. In all three organisms, a specific and sensitive receptor-mediated perception system is suggested. By comparing the activity of synthetic SL analogs on Arabidopsis root-hair elongation, Orobanche aegyptiaca seed germination, and hyphal branching of the AM fungus Glomus intraradices, we found that each of the tested organisms differs in its response to the various examined synthetic SL analogs. Structure–function relations of the SL analogs suggest substitutions on the A-ring as the cause of this variation. Moreover, the description of competitive antagonistic analogs suggests that the A-ring of SL can affect not only affinity to the receptor, but also the molecule’s ability to activate it. The results support the conclusion that Arabidopsis, Orobanche, and AM fungi possess variations in receptor sensitivity to SL analogs, probably due to variation in SL receptors among the different species. [ABSTRACT FROM AUTHOR]

Since the first report and due to its handiness and wide scope, the Suzuki-Miyaura (SM) cross coupling reaction has become a routine methodology in many laboratories worldwide. With respect to other common transition metal catalyzed cross couplings, the SM reaction has been so far less exploited as a tool to introduce an acyl function into a specific substrate. In this review, the various approaches found in the literature will be considered, starting from the direct SM acylative coupling to the recent developments of cross coupling between boronates and acyl chlorides or anhydrides. Special attention will be dedicated to the use of masked acyl boronates, alkoxy styryl and alkoxy dienyl boronates as coupling partners. A final section will be then focused on the acyl SM reaction as key synthetic step in the framework of natural products synthesis. [ABSTRACT FROM AUTHOR]

The enantiodivergent synthesis of the Streptomyces alka-loid 4-ep/-SS20846A was based on a Takai olefination/Suzuki-Miyaura coupling sequence for the highly stereoselective introduc-tion of the EE-pentadienyl side chain on the piperidine skeleton. Optical separation of a key hydroxylated enamide ester, prepared by palladium-catalyzed methoxycarbonylation of a lactam-derived enol phosphate, was successfully achieved by both lipase-catalyzed kinetic resolution and semipreparative HPLC. This approach al-lowed us to obtain the enantiopure target alkaloid in 35-38% yield over six steps. [ABSTRACT FROM AUTHOR]

Background: Strigolactones (SLs) are recently identified plant hormones modulating root and shoot branching. Besides their endogenous role within the producing organism, SLs are also key molecules in the communication of plants with arbuscular mycorrhizal (AM) fungi and parasitic weeds. In fact SLs are exuded into the rhizosphere where they act as a host-derived signal, stimulating the germination of the seeds of parasitic plants which would not survive in the absence of a host root to colonize. Similarly, their perception by AM fungi causes extensive hyphal branching; this is a prerequisite for effective root colonization, since it increases the number of potential contact points with the host surface. In spite of the crucial and multifaceted biological role of SLs, there is no information on the receptor(s) which bind(s) such active molecules, neither in the producing plants, or in parasitic weeds or AM fungi. Results: In this work, we applied homology modelling techniques to investigate the structure of the protein encoded by the gene Dwarf14, which was first identified in rice as conferring SLs insensitivity when mutated. The best sequence identity was with bacterial RsbQ. Both proteins belong to the superfamily of alpha/beta-fold hydrolases, some members of which play a role in the metabolism or signalling of plant hormones. The Dwarf14 (D14) structure was refined by means of molecular dynamics simulations. In order to support the hypothesis that D14 could be an endogenous SLs receptor, we performed docking experiments with a natural ligand. Conclusions: It is suggested that D14 interacts with and thereby may act as a receptor for SLs in plants. This hypothesis offers a starting point to experimentally study the mechanism of its activity in vivo by means of structural, molecular and genetic approaches. Lastly, knowledge of the putative receptor structure will boost the research on analogues of the natural substrates as required for agricultural applications. [ABSTRACT FROM AUTHOR]

This review is an overview of the last ten years' use of the Mizoroki-Heck coupling applied to 1,2- and 1,3-dienes. Since both these systems form π-allyl palladium intermediates in Pd(0) coupling, they show particular chemical behavior. Many examples of 1,2-dienes Heck reactions are presented. 1,2-Dienes are important substrates because of their high reactivity that makes them useful building blocks for the synthesis of biologically relevant structures. [ABSTRACT FROM AUTHOR]

A new method for protecting alcohols as tert-butyl ethers is reported. The reaction is performed in tert-butyl acetate in the presence of a catalytic amount of HClO4. The process is extremely efficient and primary and secondary alcohols as well as diols are protected under very mild conditions. Remarkably, tert-butyl acetate can be easily recovered after the workup of the reaction and recycled. [ABSTRACT FROM AUTHOR]