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Samarium metal and samarium diiodide have become important tools as selective cyclopropanating agents in organic synthesis due to their high chemo- and stereoselectivity. Therefore, Sm and SmI2are the ideal reagents to prepare cyclopropane derivatives. This tutorial reviewhighlights C–C multiple bond cyclopropanation processes promoted by samarium or samarium diiodide. [ABSTRACT FROM AUTHOR]

Lawsone (2-hydroxy-1,4-naphthoquinone) reacts with latent fingermark deposits on paper surfaces to yield purple-brown impressions of ridge details which are also photoluminescent; this compound represents the first in a completely new class of fingermark detection reagents. [ABSTRACT FROM AUTHOR]

TiO2(rutile–anatase, R–A)/Ti3C2Tx heterophase junction (HPJ)–Schottky junction (SHJ) composites oxidized in situ by Ti3C2Tx MXenes were synthesized via a one-step hydrothermal method using Ti3C2Tx MXenes as the Ti source and water as the solvent. There was no need for the induction and oxidation of other chemical reagents in the reaction, the reaction conditions were green and non-toxic, and the experimental operation was simple. The number of TiO2(R–A) HPJs and Ti3C2Tx SHJs can be regulated by changing the reaction temperature and time. The optimized photocatalyst exhibited a large number of TiO2(R–A) HPJs attached to the surface of Ti3C2Tx. TiO2(R–A)/Ti3C2Tx-200 °C-15 h showed a photocatalytic N2 reduction efficiency of 59.35 μmol L−1 h−1. The photoelectrochemical properties of the photocatalyst indicated that TiO2(R–A) HPJs and Ti3C2Tx SHJs have synergistic effects on the separation of photogenerated charges. Under the condition of photoexcitation, the photogenerated charge generated by TiO2 was separated at the rutile/anatase interface and transferred in the form of type II heterojunctions. Owing to the effect of Ti3C2Tx SHJs, it can quickly transfer and store holes on TiO2. Thus, the photocatalyst had remarkable photogenerated charge separation efficiency; TiO2(R–A)/Ti3C2Tx-200 °C-15 h had the strongest photocatalytic performance. This provides a new way to rationally design homogeneous heterojunctions for photocatalytic applications. [ABSTRACT FROM AUTHOR]

The SlipChip is a microfluidic device designed to perform multiplexed microfluidic reactions without pumps or valves. The device has two plates in close contact. The bottom plate contains wells preloaded with many reagents; in this paper plates with 48 reagents were used. These wells are covered by the top plate that acts as a lid for the wells with reagents. The device also has a fluidic path, composed of ducts in the bottom plate and wells in the top plate, which is connected only when the top and bottom plate are aligned in a specific configuration. Sample can be added into the fluidic path, filling both wells and ducts. Then, the top plate is “slipped”, or moved, relative to the bottom plate so the complementary patterns of wells in both plates overlap, exposing the sample-containing wells of the top plate to the reagent-containing wells of the bottom plate, and enabling diffusion and reactions. Between the two plates, a lubricating layer of fluorocarbon was used to facilitate relative motion of the plates. This paper implements this approach on a nanoliter scale using devices fabricated in glass. Stability of preloaded solutions, control of loading, and lack of cross-contamination were tested using fluorescent dyes. Functionality of the device was illustrated viacrystallization of a model membrane protein. Fabrication of this device is simple and does not require a bonding step. This device requires no pumps or valves and is applicable to resource-poor settings. Overall, this device should be valuable for multiplexed applications that require exposing one sample to many reagents in small volumes. One may think of the SlipChip as an easy-to-use analogue of a preloaded multi-well plate, or a preloaded liquid-phase microarray. [ABSTRACT FROM AUTHOR]

The reactions of 1-aminoalkylphosphonic acids with bromine–water, chlorine–water and iodine–water were investigated. The formation of phosphoric(v) acid, as a result of a halogen-promoted cleavage of the Cα–P bond, accompanied by nitrogen release, was observed. The dephosphonylation of 1-aminoalkylphosphonic acids was found to occur quantitatively. In the reactions of 1-aminoalkylphosphonic acids with other halogen–water reagents investigated by 31P NMR, scission of the Cα–P bond was also observed, the reaction rates being comparable for bromine and chlorine, but much slower for iodine. [ABSTRACT FROM AUTHOR]

In the last two decades, microfluidic technology has emerged as a highly efficient tool for the study of various chemical and biological reactions. Recently, we reported that high-throughput detection of various concentrations of a reagent is possible using a continuous gradient microfluidic channel combined with a surface-enhanced Raman scattering (SERS) detection platform. In this continuous flow regime, however, the deposition of nanoparticle aggregates on channel surfaces induces the “memory effect,” affecting both sensitivity and reproducibility. To resolve this problem, a SERS-based gradient droplet system was developed. Herein, the serial dilution of a reagent was achieved in a stepwise manner using microfluidic concentration gradient generators. Then various concentrations of a reagent generated in different channels were simultaneously trapped into the tiny volume of droplets by injecting an oil mixture into the channel. Compared to the single-phase regime, this two-phase liquid/liquid segmented flow regime allows minimization of resident time distributions of reagents through localization of reagents in encapsulated droplets. Consequently, the sample stacking problem could be solved using this system because it greatly reduces the memory effect. We believe that this SERS-based gradient droplet system will be of significant utility in simultaneously monitoring chemical and biological reactions for various concentrations of a reagent. [ABSTRACT FROM AUTHOR]

This work introduces, for the first time, simultaneous monitoring of fluorescence and absorbance using Bead Injection in a Lab-on-valve format. The aim of the paper is to show that when the target species, cells immobilized on a stationary phase, are exposed to reagents under well-controlled reaction conditions, dual monitoring yields valuable information. The applicability of this technique is demonstrated by the development of a Bead Injection method for automated measurement of cell density and intracellular hydrogen peroxide. [ABSTRACT FROM AUTHOR]

A new oscillatory microfluidic junction is described, which enables the consistent formation of highly uniform and complex double emulsions, and is demonstrated for the encapsulation of four different reagents within the inner droplets (called cores) of the double emulsion droplets. Once the double emulsion droplets had attained a spherical form, the cores assumed specific 3D arrangements, the orchestration of which appeared to depend upon the specific emulsion morphology. Such double emulsion droplets were used as templates to produce highly compartmentalised microcapsules and multisomes. Based on these construct models, we numerically demonstrated a model chemical reaction sequence between and within the liquid cores. This work could provide a platform to perform space/time-dependent applications, such as programmed experiments, synthesis, and delivery systems. [ABSTRACT FROM AUTHOR]

Chloride-incorporated dodecavanadates show two distinct structures of the monoprotonated-form [HV12O32(Cl)]4− (closed-V12) with a spherical closed-structure and the opened-form [V12O32(Cl)]5− (opened-V12). The reaction of closed-V12 with a stoichiometric amount of ethylenediamine drives the structure transformation reaction to opened-V12, quantitatively. From time dependent observations of 51V NMR, a tube-type intermediate [V12O32(Cl)]5− (tube-V12) was observed in the transformation process. Isolation of the intermediate was achieved by the deprotonation reaction of closed-V12 with diethylamine, and the structure transformation was confirmed by using the isolated intermediate. The reverse transformation from opened-V12 to closed-V12 was also achieved by addition of trifluoroacetic acid. The geometrical difference between closed-V12 and opened-V12 is reflected in the reactivity difference to the external reagents, and this was demonstrated by examining the chloride removal reaction by using a silver cation. The incorporated chloride was preserved in the closed-V12 cage even in the presence of a silver cation. In contrast, the chloride in opened-V12 was removed as AgCl by the silver cation. In addition, by the reaction of chloride-free opened-V12 with a quantitative amount of {Et4N}Cl retrieved opened-V12, showing the capability of opened-V12 to recapture a guest chloride in the cavity. This transformation between two isomeric dodecavanadate structures is regarded as the movement of a molecular mitt to catch a ball and secure it. [ABSTRACT FROM AUTHOR]

The nucleophilic properties of the title compound [(2,6-i-Pr2C6H3N)2(Cl)W(η2-t-Bu2P=P)]Li·3DME (1) were investigated in reactions with selected electrophilic reagents such as MeI, M(CO)5THF (M = Cr, Mo, W), AlCl3, and GaCl3. Methylation of 1 by MeI yields phosphanylphosphido complexes [(2,6-i-Pr2C6H3N)2W(X)(1,2-η-t-Bu2P=P–CH3)] (X = Cl, I) (2-Cl/2-I) with the formation of a new P–C bond. Moreover, 1 reacts with electrophilic compounds [(OC)5M·THF] (M = Cr, Mo, W) to yield a series of novel dinuclear phosphanylphosphinidene complexes [(2,6-i-Pr2C6H3N)2(Cl)W(1,2-η-t-Bu2P=P–M(CO)5)]Li·3DME (3, 4, 5) with very long P–M distances. Adducts [(2,6-i-Pr2C6H3N)2(Cl)W(1,2-η-t-Bu2P=P–MCl3)]Li·3DME (6, 7) formed by reaction of 1 with GaCl3 and AlCl3 are labile and dissociate into 1 and MCl3 (M = Ga, Al). The outcomes of reactions were monitored by 31P-NMR spectroscopy. Furthermore, the structures of the isolated complexes 2-Cl/2-I, 3, 4, and [(2,6-i-Pr2C6H3N)2(Cl)W(1,2-η-t-Bu2P=P–W(t-Bu2PH)(CO)3COLi·2DME] (5-P) were confirmed unambiguously by X-ray diffraction studies. [ABSTRACT FROM AUTHOR]

The thiophosphinidene complex [Mo2Cp2(μ–κ2:κ1,η6-SPMes*)(CO)2] (Mes* = 2,4,6-C6H2tBu3) reacted with [Co2(CO)8] at room temperature or below to give several of the following phosphinidene-bridged products, depending on reaction conditions: the MoCo complexes [CoMoCp(μ–κ1:κ1,η6-PMes*)(CO)3] and [CoMoCp(μ-PMes*)(CO)5] (Co–Mo = 2.972(1) Å), the MoCo3 cluster [Co3MoCp(μ3-PMes*)(CO)9] (Co–Mo = 2.664(1), 2.810(1) Å), and the sulphido-bridged tetranuclear complexes [Co2Mo2Cp2(μ–κ1:κ1:κ1,η4-PMes*)(μ3-S)(CO)7] and [Co3MoCp(μ–κ1:κ1:κ1,η4-PMes*)(μ3-S)(CO)8]. In contrast, the thiophosphinidene complex [Mo2Cp2(μ–κ2:κ1,η4-SPMes*)(CO)3] reacted with the same cobalt reagent selectively to give the above Mo2Co2 complex in very high yield. The latter could be decarbonylated photochemically to give [Co2Mo2Cp2(μ–κ1:κ1:κ1,η6-PMes*)(μ3-S)(CO)6] (Co–Co = 2.435(3), Co–Mo = 2.769(2), 2.798(2) Å), after an η4- to η6-haptotropic rearrangement of the aryl ring of the phosphinidene ligand that could be reversed upon reaction with CO. The related complex [Mo2Cp2(μ–κ2:κ1,η4-SPMes*)(CO)2(CNtBu)], however, displayed poor selectivity towards the cobalt dimer and yielded a mixture of CoMo complexes [CoMoCp(μ-PMes*)(CO)5] and [CoMoCp(μ-PMes*)(CO)3(CNtBu)2], and the tetranuclear sulphido-bridged ones [Co2Mo2Cp2(μ–κ1:κ1:κ1,η4-PMes*)(μ3-S)(CO)6(CNtBu)] (Co–Co = 2.533(1), Co–Mo = 2.7485(9), 2.770(1) Å) and [Co3MoCp(μ–κ1:κ1:κ1,η4-PMes*)(μ3-S)(CO)7(CNtBu)] (Co–Co = 2.4120(7) to 2.5817(7) Å). This reduction in selectivity might have an electronic origin rather than a steric origin, since the related but cationic substrate [Mo2Cp2{μ–κ2:κ1,η5-SP(C6H3tBu3)}(CO)2(CNtBu)]BAr′4 [Ar′ = 3,5-C6H3(CF3)2] reacted with [Co2(CO)8] more selectively to give the sulphido-bridged Co2Mo2 complex [Co2Mo2Cp2{μ–κ1:κ1:κ1,η5-P(C6H3tBu3)}(μ3-S)(CO)6(CNtBu)]BAr′4, along with small amounts of the Co3Mo complex [Co3MoCp{μ–κ1:κ1:κ1,η5-P(C6H3tBu3)}(μ3-S)(CO)7(CNtBu)]BAr′4 (Co–Co = 2.414(2) to 2.560(2) Å). The structure of the new complexes was analyzed on the basis of the corresponding X-ray diffraction and spectroscopic data, and likely reaction pathways were discussed on the basis of the above results and some additional experiments. [ABSTRACT FROM AUTHOR]

Lithium organoamidocuprates of the general stoichiometry LiCuR(NR'2) are an important class of organocopper reagents and have found widespread application in conjugate addition and other bond-forming reactions. The dependence of the structures and equilibrium of these species on the steric and electronic properties of the amido group is reported in both the solid state and in solution. Three different cuprate complexes have been crystallographically characterized: the organoamidocuprate [Cu2Li2Mes2TMP2] (2) (TMP = 2,2,6,6-tetramethylpiperidide) which is shown to adopt a head-to-tail conformation; [Cu2Li2-(N(CH2Ph)CH2CH2NMe2)4] (3) which is a homoamidocuprate and contains additional coordination of the lithium centres from intra-molecular tertiary amine groups; and the diastereomeric organoamidocuprate [Cu2Li2Mes2(N(R-CH(Ph)Me)(CH2CF3))2] (4) which adopts a head-to-head conformation. Complex 4 is unique in being the first crystallographically characterised example of a head-to-head isomer of a heterocuprate, and its structure also has implications for the use of scalemic amidocuprates in asymmetrically induced conjugate addition. The solution equilibria of all new complexes have also been studied using 7Li NMR spectroscopy, and in each case the species observed in the crystal structure was shown to also be the predominant isomer in solution. [ABSTRACT FROM AUTHOR]

Exploring the reactivity of sodium butylmagnesiate reagent [{Na(THF)6}+{(Ph2Si(NAr*)2)Mg(Bu)(THF)}-] (1) supported by the bulky chelating silyl(bisamido) ligand {Ph2Si(NAr*)2}2- (Ar* = 2,6-iPr2-C6H3) towards N-methylbenzimidazole (bImMe), pyrrole and 2,6-diisopropylaniline (NH2Ar*), this study provides new insights into the ability of this bimetallic base to facilitate direct Mg-H exchange reactions as well as to exhibit polybasicity. Thus 1 effectively promotes the deprotomagnesiation of bImMe under mild reaction conditions to give the α-metallated intermediate [{Na(THF)5}2 +{(Ph2Si(NAr*)2)Mg(bImMe*)}2-] (2) (bImMe* = 2-N-methylbenzimidazolyl). Analysis of crystallographic and NMR data of 2 combined with DFT calculations show that the metallated C in the bImMe* ligands possesses a significant carbenic character. Contrasting with previous studies of benzothiazole (btz), 1 does not react with an excess of bImMe even under forcing refluxing conditions. Contrastingly, the amination reactions of equimolar amounts of 1 with pyrrole and 2,6-diisopropylaniline allowed the isolation of [{(Ph2Si(NAr*)(NHAr*))Mg- (NC4H4)2(THF)Na(THF)2}] (3) and [{Na(THF)6}+{(Ph2Si(NAr*)(NHAr*))Mg(NHAr*)2(THF)}-] (4) respectively as crystalline solids. Highlighting the ability of 1 to act as a polybasic reagent, 3 and 4 are formed as the result of the deprotonation of two molecules of the relevant amine via its butyl group and one amido arm of the silyl(bisamido) ligand. Similarly, the reactions of 1 with 3 molar equivalents of the relevant amine yielded homoleptic tris(amido) compounds [(THF)2NaMg(NC4H4)3] (5) and [{Na(THF)6}+{Mg- (NHAr*)3}-] (7), with the concomitant formation of bis(amine) Ph2Si(NHAr)2, as a result of the complete amination of 1 using its three basic sites. The structures in the solid state of 3 and 4 were elucidated by X-ray crystallography. Despite their similar constitution, these heteroleptic tris(amido)magnesiates adopt contrasting structures, with the former displaying a contacted ion-pair structure, where Na and Mg are connected by two bridging pyrrolyl anions, whereas the latter gives rise to a solvent-separated ion pair motif. To the best of our knowledge 3 represents the first crystallographically characterized magnesium compound containing an anionic non-substituted form of pyrrole. Noticeably, Mg interacts exclusively with the N atoms of the pyrrolyl ligands, forming strong α-bonds, whereas Na prefers to engage with the π-systems of both NC4-rings. [ABSTRACT FROM AUTHOR]

This paper introduces the preliminary design and optimization of a micro-Sequential Injection lab-on-valve system (μSI-LOV) with fluorescence detection for the direct determination of trace Zn2+in an unacidified seawater matrix. The method capitalizes on the sensitivity and selectivity of FluoZin-3, which was originally designed to measure zinc in living cells. The optimum reaction conditions, sources of blank signal and physical parameters of the μSIA-LOV are evaluated with the requirements of trace metal analysis in mind, namely high sensitivity and low background signals. A detailed investigation of the effect of sample and reagent sequencing on sensitivity is presented for the first time using μSIA-LOV. We find that the order of sequencing greatly influences peak shape and analytical sensitivity with the highest and smoothest peaks obtained when a large volume of sample (75 μL) is aspirated last in the sequence prior to flow reversal and detection. The optimized reaction conditions and reagent/sample sequencing protocol yield a detection limit of 0.3 nM Zn2+, high precision (RSD < 2.5%), a linear quantification range up to 40 nM and an analytical cycle of ∼1 min per sample. This work demonstrates that μSI-LOV is capable of attaining detection limits that are close to those needed for open ocean determinations of Zn2+without preconcentration or separation of the analyte from the seawater matrix. The low reagent consumption (50 μL per sample), full automation and minimal maintenance requirements of μSI-LOV make it well suited for shipboard analysis and, eventually, for development to meet the pressing need for trace element measurements in unattended locations. [ABSTRACT FROM AUTHOR]

This review is a guided tour along the activation modes and reactivity of B–B, B–Si, B–N, B–S, B–Se and B–P reagents, in the absence of any transition metal complex. Here are disclosed the general concepts related to the homolytic and heterolytic cleavage of B–B and B–interelement bonds, as well as the generation of new C–B and C–interelement bonds, in a selective way. The greener consequences of these novel routes facilitate the gram scale preparations of target functionalised organic compounds. Intrinsic data about the suggested mechanisms and spectroscopic evidence that supports the innovative theories are provided along the review. Since this is a stimulating area of work that has emerged within the last decade, this overview serves as the basis to understand the new trends and hopefully to generate inspiration for future discoveries in the field. [ABSTRACT FROM AUTHOR]

The mixed diaryl titanates were used for the first time to modify the reactivity of two aryl Grignard reagents. Two titanate intermediates, Ar[Ar′Ti(OR)3]MgX and Ar′[ArTi(OR)3]MgX, formed via alternating the sequence of combining Grignard reagents with ClTi(OR)3 showed a significant reactivity difference. Taking advantage of such different reactivity, two highly structurally similar aryl groups could be facilely assembled through iron-catalyzed oxidative cross-couplings using oxygen as the oxidant. [ABSTRACT FROM AUTHOR]

Reaction of the lithiated N-heterocyclic carbene [:C[N(2,6-iPr2C6H3)]2(CH)CLi]n (LiIPr) with KOtBu in diethylether (Et2O) afforded the novel organo-potassium compound [:C[N(2,6-iPr2C6H3)]2(CH)CK(THF)2] (KIPr·2THF). Both LiIPr and KIPr can be interpreted as ditopic carbanionic carbenes (or alkali metal salts of anionic "dicarbenes") and are interesting precursors for the synthesis of novel metal complexes bearing carbanionic carbenes as ligands. Reaction of KIPr with M[N(SiMe3)2]2 (M = Zn, Sn) afforded salts of the anionic three coordinate complexes [M{C(CH)[N(2,6-iPr2C6H3)]2C:}{N(SiMe3)2}2]- (M = Zn (1) and Sn (2)). Contrasting reactivity was observed for the other group 14 bis-amide compounds M[N(SiMe3)2]2 (M = Ge, Pb), which initially appear to yield analogous 1:1 complexes (M = Ge (3) and Pb (4)), however over time give rise to compounds bearing two ditopic carbanionic carbenes ([M{C(CH)[N(2,6-iPr2C6H3)]2C:}2-{N(SiMe3)2}]-; Ge (5) and Pb (6)) and the tris-amide anions ([M{N(SiMe3)3}]-), presumably via a Schlenktype equilibrium. Compounds 5 and 6 can be directly synthesized by reacting M[N(SiMe3)2]2 (M = Ge, Pb) with two equivalents of KIPr, respectively. [ABSTRACT FROM AUTHOR]

Microfluidic devices are excellent at downscaling chemical and biochemical reactions and thereby can make reactions faster, better and more efficient. It is therefore understandable that we are seeing these devices being developed and used for many applications and research areas. However, microfluidic devices are more complex than test tubes or microtitre plates and the integration of reagents into them is a real challenge. This review looks at state-of-the-art methods and strategies for integrating various classes of reagents inside microfluidics and similarly surveys how reagents can be released inside microfluidics. The number of methods used for integrating and releasing reagents is surprisingly large and involves reagents in dry and liquid forms, directly-integrated reagents or reagents linked to carriers, as well as active, passive and hybrid release methods. We also made a brief excursion into the field of drug release and delivery. With this review, we hope to provide a large number of examples of integrating and releasing reagents that can be used by developers and users of microfluidics for their specific needs. [ABSTRACT FROM AUTHOR]

We investigated the synthesis of dialkyl carbonates under solvent-free high speed ball milling conditions. We converted various metal carbonates with the assistance of metal complexing reagents into a variety of dialkyl carbonates. We also observed the increased reactivity of urea under similar reaction conditions. [ABSTRACT FROM AUTHOR]

Fine chemicals are highly pure substances that are commercially produced by chemical reactions for highly specialized applications. In most cases, however, these reactions involve stoichiometric and highly polluting steps. A possible solution is the development of processes using enzymatic, homogeneous or heterogeneous catalysts. In this review, selected examples of clean heterogeneously-catalyzed reactions applied to the synthesis of fine chemicals are reported for the purpose of highlighting the growing need for more sustainable industrial processes, i.e., processes that produce minimal waste and avoid as much as possible the use of toxic and/or hazardous reagents and solvents. A thorough knowledge of catalyst properties, reaction conditions and interactions with the reacting substrate are essential for optimizing the synthesis, thus making it possible to move on from laboratory to industrial production. [ABSTRACT FROM AUTHOR]

The development of new asymmetric methodologies that afford different structures in an enantioselective fashion is one of the most exciting goals for chemists nowadays. In this subject, lately, the use of sulfones has become a fast growing field. From the works of Tan and Shibata until the last works of Palomo, sulfones have demonstrated their versatility and power in organocatalytic asymmetric reactions. Moreover, the easy removal of sulfones with Mg or Hg/Na makes this group a perfect choice to afford easily naked alkyls. Remarkably, bissulfones can be used as nucleophiles or electrophiles, being vinyl sulfones excellent electrophiles, while bismethylensulfones derivatives such as fluoro are excellent nucleophiles. This double possibility has been studied by several research groups, leading to new methodologies that allow obtaining formally simple alkylation in an enantioselective fashion, by using organocatalysis. The aim of this tutorial review is to summarize the last trends in the use of sulfones in organocatalytic processes, giving a complete scenario of these new reagents. [ABSTRACT FROM AUTHOR]

Chemical reactions and processes often involve cationic reagents, intermediates or products in prochiral or chiral racemic form. To afford instead non-racemic compounds, an asymmetric ion pairing of the cations with chiral anionic counterions can be considered. This review presents recent examples of the synthesis and use of chiral anions for such stereoselective purposes. [ABSTRACT FROM AUTHOR]

A range of chlorophosphoramidites have been prepared in ionic liquids and compared with material synthesised in molecular solvents. Through the use of ionic liquids as reaction media the moisture sensitivity and impurity issues hampering existing traditional synthetic routes have been eased. Not only can stock chemicals be used without purification, but the reactions may be conducted at room temperature and at high concentrations. Furthermore, reaction times are reduced and rapid addition of reagents is possible whilst retaining tight control over product selectivity. Beyond their role as reaction media, ionic liquids also present a unique storage medium for these highly moisture sensitive chlorophosphoramidites. [ABSTRACT FROM AUTHOR]

This tutorial reviewcovers recent developments in catalytic carbocyclisation of functionalised alkynes with external nucleophiles catalysed by gold, platinum and other electrophilic metals. Substrates of such reactions require a tethered functionality to react with the alkyne to complete a carbocyclic ring. We classify the reactions according to the tethered functionalities to illustrate the diversity of the carbocyclisations; these substrates include: 1 alkyne–alkyne, 2 alkyne–allene, 3 alkyne–alkene, 4 oxo-alkynes and 5 oxo-diynes and triynes. Besides their mechanistic interest, these reactions meet atom economy criteria because complex and functionalised carbocyclic products are easily assembled in a cascade sequence from readily available alkynes and nucleophiles. [ABSTRACT FROM AUTHOR]

The modification of metal–organic frameworks (MOFs) in a postsynthetic scheme is discussed in this critical review. In this approach, the MOF is assembled and then modified with chemical reagents with preservation of the lattice structure. Recent findings show amide couplings, isocyanate condensations, ‘click’ chemistry, and other reactions are suitable for postsynthetic modification (PSM). In addition, a number of MOFs, from IRMOF-3 to ZIF-90, are amenable to PSM. The generality of PSM, in both scope of chemical reactions and range of suitable MOFs, clearly indicates that the approach is broadly applicable. Indeed, the rapid increase in reports on PSM demonstrates this methodology will play an increasingly important role in the development of MOFs for the foreseeable future (117 references). [ABSTRACT FROM AUTHOR]

[Na2(thf)4(P4Mes4)] (1) (Mes = 2,4,6-Me3C6H2) reacts with one equivalent of [PtCl2(cod)] (cod = 1,5-cycloctadiene) or [PtCl2(dppe)] (dppe = bis(diphenylphosphino)ethane) to give the corresponding platinum(II) tetramesityltetraphosphane-1,4-diide complexes [Pt(P4Mes4)(cod)] (2) and [Pt(P4Mes4)(dppe)] (3). The Pt-P bonds of these complexes proved to be extraordinarily stable and did not react with insertion reagents such as tert-butyl isocyanide or cyclohexyl isocyanide. Instead, ligand transfer occurred to give [Pt(P4Mes4)(C≡NBut)2] (4) and [Pt(P4Mes4)(C≡NCy)2] (5). Further reactions of 2-5 with CO, CS2, white phosphorus, MeI and ethyl diazoacetate led either to formation of cyclo-P4Mes4 and cyclo-P3Mes3 or to unidentified products, in which no evidence of insertion of these reagents into the Pt-P bond was observed. [ABSTRACT FROM AUTHOR]

Changes of activation parameters, ΔH‡and ΔS‡, with σconstants of substituents in the reactions of carboxylic acid derivatives with anionic and neutral nucleophiles in various solvents give the δΔH‡and δΔS‡reaction constants which are linearly related for variations of substituents in substrate and nucleophile. The dependences obtained, δΔH‡vs.δΔS‡, allow estimation of the contribution of changes of the internal enthalpy, δΔH‡int, to the enthalpy reaction constant, δΔH‡, which give a single linear dependence on the Hammett ρreaction constants. The results obtained show that the substituent effects on the charge development in the transition state are governed by the magnitude of δΔH‡int. [ABSTRACT FROM AUTHOR]

The reaction of [Li(THF)4][1,8-μ-(Mes2B)C10H6] with HgCl2 affords [1,1′-(Hg)-[8-(Mes2B)C10H6]2] (3) or [1-(ClHg)-8-(Mes2B)C10H6] (4), depending on the stoichiometry of the reagents. These two new compounds have been characterized by 1H, 13C, 11B and 199Hg NMR, elemental analysis and X-ray crystallography. The cyclic voltammogram of 3 in THF shows two distinct waves observed at E1/2 −2.31 V and −2.61 V, corresponding to the sequential reductions of the two boron centers. Fluoride titration experiments monitored by electrochemistry suggest that 3 binds tightly to one fluoride anion and more loosely to a second one. Theses conclusions have been confirmed by a UV-vis titration experiment which indicates that the first fluoride binding constant (K1) is greater than 108 M−1 while the second (K2) equals 5.2 (± 0.4) × 103 M−1. The fluoride binding properties of 3 have been compared to those of [1-(Me2B)-8-(Mes2B)C10H6] (1) and [1-((2,6-Me2-4-Me2NC6H2)Hg)-8-(Mes2B)C10H6] (2). Both experimental and computational results indicate that its affinity for fluoride anions is comparable to that of 2 but significantly lower than that of the diborane 1. In particular, the fluoride binding constants of 1, 2 and 3 in chloroform are respectively equal to 5.0 (± 0.2) × 105 M−1, 1.0 (± 0.2) × 103 M−1 and 1.7 (± 0.1) × 103 M−1. Determination of the crystal structures of the fluoride adducts [S(NMe2)3][1–μ2-F] and [S(NMe2)3][3–μ2-F] along with computational results indicate that the higher fluoride binding constant of 1 arises from a strong chelate effect involving two fluorophilic boron centers. [ABSTRACT FROM AUTHOR]

The reaction of 1-(p-hydroxyaryl)cyclobutanols and phenyl iodide(iii) diacetate in hexafluoroisopropanol and water produced spiro cyclohexadienone lactones viaa domino reaction. [ABSTRACT FROM AUTHOR]

The first synthesis of the whole antiostatin family is described by using an iron-mediated carbazole synthesis, regioselective nitration at C-4 and establishing 5-isobutyl-1-nitrobiuret as a reagent for introduction of the antiostatin B side chain at C-4. [ABSTRACT FROM AUTHOR]