Single-step Transformation Research Articles

Spokewise Total Syntheses of Four Erythrina Alkaloids and Telescoped Syntheses of Six Additional Alkaloids.

Based on rich sulfur-involving chemical transformations, a novel spokewise synthetic strategy, a subclass of the collective strategies, has been developed to concisely synthesize four erythrina alkaloids through a single-step transformation from a common synthetic precursor. Moreover, six additional erythrina alkaloids have also been synthesized by subsequent 1-2 steps chemical transformations. The current synthetic approaches provide a valuable platform for collective total syntheses of erythrina alkaloids and pseudo-natural erythrina alkaloids.

Mechanical behavior of Ni[formula omitted]Ti[formula omitted] shape memory alloys with void defects

Superelasticity of NixTi100−x B2 shape memory alloys (SMAs) with different atomic compositions and void defects are investigated using molecular dynamics simulations. In the first part of this study, the effect of species content on the martensitic transformation is explored, with x ranging from 48% to 52%. All samples displayed similar behavior under compression, where transformation from B2 to B19’ was observed. On the other hand, under tension, both Ni48Ti52 and Ni50Ti50 displayed single-step transformation from B2 to L10, while the Ni-rich sample exhibited a simultaneous double-step transformation from B2 to B19’ to L10. The mechanical performance of the samples with voids under compression was also explored. The void surface was found to act as a barrier, hindering the phase transformation to B19’ structure and its elastic response, ultimately reducing the maximum stress prior to fracture. Statistical methods established connections between various properties and offered mathematical models to correlate the initial setup variables Ni content and void radius, with properties derived from deformation tests. Consequently, this study provides both an atomic description of the deformation behavior of NiTi SMAs and a statistical framework for establishing the relationships between materials properties.

Techno-economic and life-cycle analysis of single-step catalytic conversion of bioethanol to fuel blendstocks over Ni-doped HZSM-5 zeolite catalyst

This work presents techno-economic and life-cycle studies focusing on the catalytic conversion of ethanol into hydrocarbon fuel blendstocks. These analyses benefit from recent advancements in catalyst and process development. The consolidated alcohol dehydration and oligomerisation for ethanol-to-hydrocarbon (CADO-ETH) conversion approach, described here, achieves a single-step transformation of wet ethanol vapour into hydrocarbons and H2O using a Ni-doped HZSM-5 catalyst. Catalyst cost estimation using the CatCost model showed that commercial synthesis of Ni/HZSM-5 incurred significant processing costs, which varied greatly depending on the manufacturing scale. Hence, catalyst production using 100 % and 50 % baseline scale production (BSP) requirements resulted in net catalyst costs of $31.4 and $69.9/kg, respectively. Although current CADO products closely resemble gasoline blendstocks, they can also be blended with gasoline fuel at low levels. There is potential for higher-level blending in the future. The operating and annualised capital costs for converting wet ethanol into fuel blendstocks were predicted to be $0.05/L at present and projected to decrease to $0.03/L in the future. This cost is comparable to the unit energy cost of synthesising anhydrous ethanol from wet ethanol, which is $0.02/L. At an oil price of 100 $/bbl, the expected minimum selling prices for the fuel blendstocks produced by CADO are similar to the prices for conventional gasoline. However, at an oil price of $60/bbl, the estimated minimum selling prices for CADO-derived blendstocks are not competitive with conventional gasoline. Nevertheless, considering existing production incentives, the projected minimum selling price for gasoline blendstock is comparable to the oil price of $60/bbl. The LCA shows that the CO2 emissions of gasoline produced from crude oil are 90.2 gCO2 e/MJ, which is 25 %, 53 % and 63 % more than the emissions of gasoline produced from corn starch, sugarcane, and cane cellulose, respectively. The results of this study indicate that the single-step CADO-ETH technology is promising for the production of renewable fuels and offers a potential pathway to reduce the carbon footprint.

Silver-Catalyzed Skeletal Editing of Benzothiazol-2(3H)-ones and 2-Halogen-Substituted Benzothiazoles as a Rapid Single-Step Approach to Benzo[1,2,3]thiadiazoles.

A facile silver(I)-catalyzed reaction of benzothiazol-2(3H)-ones with NaNO2, or using AgNO2 directly, enables a single-step transformation to the corresponding benzo[1,2,3]thiadiazoles in moderate to excellent yields, with wide functional group compatibility. It can also be performed in a one-pot manner from readily available 2-halobenzothiazoles. This intriguing transformation involving an atom replacement in the S,N-heteroarene ring thus provides rapid access to isobenzothiadiazoles (while avoiding the usage of unstable precursors) and also expands the toolbox of modern skeletal editing reactions.

Visual Reasoning: From State to Transformation.

Most existing visual reasoning tasks, such as CLEVR in VQA, ignore an important factor, i.e., transformation. They are solely defined to test how well machines understand concepts and relations within static settings, like one image. Such state driven visual reasoning has limitations in reflecting the ability to infer the dynamics between different states, which has shown to be equally important for human cognition in Piaget's theory. To tackle this problem, we propose a novel transformation driven visual reasoning (TVR) task. Given both the initial and final states, the target becomes to infer the corresponding intermediate transformation. Following this definition, a new synthetic dataset namely TRANCE is first constructed on the basis of CLEVR, including three levels of settings, i.e., Basic (single-step transformation), Event (multi-step transformation), and View (multi-step transformation with variant views). Next, we build another real dataset called TRANCO based on COIN, to cover the loss of transformation diversity on TRANCE. Inspired by human reasoning, we propose a three-staged reasoning framework called TranNet, including observing, analyzing, and concluding, to test how recent advanced techniques perform on TVR. Experimental results show that the state-of-the-art visual reasoning models perform well on Basic, but are still far from human-level intelligence on Event, View, and TRANCO. We believe the proposed new paradigm will boost the development of machine visual reasoning. More advanced methods and new problems need to be investigated in this direction.

Arenes and Heteroarenes C-H Functionalization Under Enabling Conditions: Electrochemistry, Photoelectrochemistry & Flow Technology.

C-H bond functionalization generates molecular complexity in single-step transformation. However, the activation of C-H bonds requires expensive metals or stoichiometric amounts of oxidizing/reducing species. In many cases, they often require pre-functionalization of starting molecules. Such pre-activating measures cause waste generation and their separation from the final product is also troublesome. In such a scenario, reactions activating elements generating from renewable energy resources such as electricity and light would be more efficient, green, and cost-effective. Further, incorporation of growing flow technology in chemical transformation processes will accelerate the safer accesses of valuable products. Arenes & heteroarenes are ubiquitous in pharmaceuticals, natural products, medicinal compounds, and other biologically important molecules. Herein, we discussed enabling tools and technologies used for the recent C-H bonds functionalization of arenes and heteroarenes.

Development of a low-carbon carbide-free nanostructured bainitic steel with extremely high strength and toughness

High-carbon carbide-free nano-bainitic steels show extremely high strength but relatively poor fracture toughness and welding prospects. Therefore, an attempt has been made to develop a strong and damage tolerant low-carbon bainitic steel in the current study by taking recourse to two-step austempering at 350 °C for 20 min and 250 °C for 7 h (20min-TS) and the properties have been compared with another block prepared using a single step transformation for 3 h at 350 °C (3hr-SS). Two stage heat-treatment leads to lath thickness refinement in addition to block refinement as compared to a single step transformation. Moreover, a NW misorientation developed in 20min-TS as compared to KS in a single-stage transformation. An average bainitic lath thickness below 100 nm in a steel having 0.26 wt% carbon has been obtained in 20min-TS which in turn results in an ultimate tensile strength of 1.5 GPa, percentage elongation of 18.5, impact energy of 31 J and plane-strain fracture toughness of 82 MPam−1/2. This is an around two and a half times increase in toughness without significantly compromising on the strength when compared to nanostructured bainitic steels produced in a similar duration of austempering for high carbon steels.

Z-Trisubstituted α,β-Unsaturated Esters and Acid Fluorides through Stereocontrolled Catalytic Cross-Metathesis.

Catalytic cross-metathesis (CM) reactions that can generate trisubstituted alkenes in high stereoisomeric purity are important but remain limited in scope. Here, CM reactions are introduced that generate Z-trisubstituted α-methyl, α,β-unsaturated, alkyl and aryl esters, thiol esters, and acid fluorides. Transformations are promoted by a Mo bis-aryloxide, a monoaryloxide pyrrolide, or a monoaryloxide chloride complex; air-stable and commercially available paraffin tablets containing a Mo complex may also be used. Alkyl, aryl, and silyl carboxylic esters as well as thiol esters and acid fluoride reagents are either purchasable or can be prepared in one step. Products were obtained in 55-95% yield and in 88:12->98:2 Z/E ratio (typically >95:5). The applicability of the approach is highlighted by a two-step conversion of citronellol to an isomintlactone precursor (1.7 g, 73% yield, and 97:3 Z/E) and a single-step transformation of lanosterol acetate to 3-epi-anwuweizic acid (72% yield and 94:6 Z/E). Included are the outcomes of DFT studies, regarding several initially puzzling catalyst activity trends, providing the following information: (1) it is key that a disubstituted Mo alkylidene, generated by a competing homo-metathesis (HM) pathway, can re-enter the productive CM cycle. (2) Whereas in a CM cycle the formation of a molybdacyclobutane is likely turnover-limiting, the collapse of related metallacycles in a HM cycle is probably rate-determining. It is therefore the relative energy barrier required for these steps that determines whether CM or HM is dominant with a particular complex.

Assembly of Diverse [60]Fullerene-Fused Tricyclic Scaffolds via a Palladium-Catalyzed Cascade [2 + 2 + 2] Annulation Reaction.

Herein, a concise and robust approach for the highly efficient assembly of [60]fullerene-fused tricyclic scaffolds has been developed through a palladium-catalyzed cascade [2 + 2 + 2] annulation process. Diverse tricyclic scaffolds incorporating various ring sizes (6-19 membered) and types (carbocycles and N- and O-heterocycles) can be expediently constructed in a single-step transformation.

Asymmetric Brønsted Acid Catalyzed Cycloadditions of ortho-Quinone Methides and Related Compounds

AbstractThis review summarizes recent developments in the area of Brønsted acid catalyzed, enantioselective cycloadditions of ortho-quinone methides, ortho-quinone methide imines as well as heterocyclic indole- and pyrrole-based methides. In a straightforward and single-step transformation complex polycyclic N- and O-heterocyclic scaffolds are accessible, with typically good yields and excellent stereocontrol, from simple benzyl and heterobenzyl alcohols upon acid-catalyzed dehydration. The transient precursors are hydrogen-bonded to a chiral Brønsted acid which controls the enantioselectivity of the process.1 Introduction2 Cycloadditions of ortho-Quinone Methides2.1 Brønsted Acid Catalyzed Processes2.2 Cooperative Brønsted Acid/Transition-Metal-Catalyzed Processes3 Cycloadditions of ortho-Quinone Methide Imines4 Cycloadditions of Indolyl-3-methides5 Cycloadditions of Indolyl-2-methides5.1 Brønsted Acid Catalyzed Processes5.2 Cooperative Brønsted Acid/Transition-Metal-Catalyzed Processes6 Cycloadditions of Pyrrolyl-2-methides7 Cycloadditions of Pyrrolyl-3-methides8 Conclusions

Strong acid-promoted skeletal remodeling of the aphid pigment: red uroleuconaphin to green viridaphin

A strong acid-promoted single-step transformation of red uroleuconaphin A1 to green viridaphins A1 and A2 is described here.

An Iridium Catalytic System Compatible with Inorganic and Organic Nitrogen Sources for Dual Asymmetric Reductive Amination Reactions.

Asymmetric reductive amination (ARA) is one of the most promising methods for the synthesis of chiral amines. Herein we report our efforts on merging two ARA reactions into a single-step transformation. Catalyzed by a complex formed from iridium and a steric hindered phosphoramidite, readily available and inexpensive aromatic ketones initially undergo the first ARA with ammonium acetate to afford primary amines, which serve as the amine sources for the second ARA, and finally provide the enantiopure C2 -symmetric secondary amine products. The developed process competently enables the successive coupling of inorganic and organic nitrogen sources with ketones in the same reaction system. The Brønsted acid additive plays multiple roles in this procedure: it accelerates the formation of imine intermediates, minimizes the inhibitory effect of N-containing species on the iridium catalyst, and reduces the primary amine side products.

Improving the hydrogen cycling properties by Mg addition in Ti-V-Zr-Nb refractory high entropy alloy

A novel high entropy alloy containing Mg and refractory elements has been prepared by mechanochemical synthetic method under inert atmosphere. The Mg0.10Ti0.30V0.25Zr0.10Nb0.25 alloy adopts a single-phase bcc lattice and can absorb hydrogen within 1 minute at room temperature forming a hydride phase with 1.7 H/M (2.7 wt.%) capacity. During the reaction with hydrogen the alloy undergoes a single-step and reversible phase transformation from bcc (alloy) to fcc lattice (hydride). The absorption/desorption cycling properties prove a small fading of the capacity for the first cycle followed by stabilization to 1.5 H/M (2.4 wt.%) for the next cycles. A simple comparison between this quinary HEA and the quaternary alloy containing only refractory elements Ti0.325V0.275Zr0.125Nb0.275 proves an important enhancement of the cycling properties by Mg addition. These insights seem to suggest that insertion of light-weighted metals such as, Mg, can guide future design of novel HEA with improved performances for hydrogen storage.

Expanded Helicenes as Synthons for Chiral Macrocyclic Nanocarbons.

Expanded helicenes are large, structurally flexible π-frameworks that can be viewed as building blocks for more complex chiral nanocarbons. Here we report a gram-scale synthesis of an alkyne-functionalized expanded [11]helicene and its single-step transformation into two structurally and functionally distinct types of macrocyclic derivatives: (1) a figure-eight dimer via alkyne metathesis (also gram scale) and (2) two arylene-bridged expanded helicenes via Zr-mediated, formal [2+2+n] cycloadditions. The phenylene-bridged helicene displays a substantially higher enantiomerization barrier (22.1 kcal/mol) than its helicene precursor (<11.9 kcal/mol), which makes this a promising strategy to access configurationally stable expanded helicenes. In contrast, the topologically distinct figure-eight retains the configurational lability of the helicene precursor. Despite its lability in solution, this compound forms homochiral single crystals. Here, the configuration is stabilized by an intricate network of two distinct yet interconnected helical superstructures. The enantiomerization mechanisms for all new compounds were probed using density functional theory, providing insight into the flexibility of the figure-eight and guidance for future synthetic modifications in pursuit of non-racemic macrocycles.

Dynamic re-equilibration controlled multi-step transformations in (Mn, Fe)2(P, Si) alloys

In (Mn, Fe)2(P, Si) alloys crystallographic first-order phase transformations enable strong coupling of magnetic and entropic properties, potentially leading to high-efficiency energy generation and refrigeration applications. Although hysteresis losses that limit these applications can be reduced through careful control of alloy composition, compositional tuning can also unfavorably influence transformation temperatures and magnetocaloric coupling strength. Hence, exploration of additional processing variables enabling independent control of transformation properties is crucial. In this work, we investigate the role of thermal history as an additional processing variable, exploiting thermally-activated mechanisms to control properties of non-diffusive transformations in (Mn, Fe)2(P, Si) alloys. In so doing, we report an unusual transformation-splitting phenomenon following annealing at intermediate times, where a single well-defined magneto-structural transformation evolves towards a multi-step transformation with individual steps occurring at multiple distinct temperatures. On longer annealing at the same temperatures, single-step transformation behavior is recovered. Through additional magnetic and crystallographic characterization, we show that the thermal history-controlled multi-step behavior results from sluggish thermally-activated diffusion. The two-step transformation corresponds to non-equilibrium bimodal composition distributions in the transforming phase, and these develop through a dynamic re-equilibration process as the alloy passes relatively slowly between different thermal equilibria. Together, these results suggest that thermal history primarily controls the transformation properties of (Mn, Fe)2(P, Si) alloys indirectly through the composition of one or more transforming phases. Additional investigations are needed to develop thermal history processing for decoupling hysteresis control from other transformation properties.

Hydroxylamines As Bifunctional Single-Nitrogen Sources for the Rapid Assembly of Diverse Tricyclic Indole Scaffolds.

Conventional approaches on using hydroxylamine derivatives as single nitrogen sources, for the construction of n-membered (n > 3) N-heterocycles, rely upon two chemical operations by involving sequential nucleophilic and electrophilic C-N bond formations. Here, we report a highly efficient cascade of alkyne insertion/C-H activation/amination for the rapid preparation of a myriad of tricyclic indoles, in a single-step transformation, by using bifunctional secondary hydroxylamines. It is noteworthy that judicious selection of applicable amino agents, for enabling the prior oxidative addition of aryl iodide to initial Pd(0) species and subsequent two C-N bonds formation, was the key to the success of this reaction. Control experiments indicated that a five-membered palladacyclic intermediate played a crucial role in promoting the final aminative ring closure.

Enhanced mating-type switching and sexual hybridization in heterothallic yeast Yarrowia lipolytica

Yarrowia lipolytica is a non-conventional, heterothallic, oleaginous yeast with wide range of industrial applications. Increasing ploidy can improve advantageous traits for industrial applications including genetic stability, stress resistance, and productivity, but the construction of knockout mutant strains from polyploid cells requires significant effort due to the increased copy numbers of target genes. The goal of this study was to evaluate the effectiveness of a mating-type switching strategy by single-step transformation without a genetic manipulation vestige, and to optimize the conventional method for increasing ploidy (mating) in Y. lipolytica. In this study, mating-type genes in haploid Y. lipolytica cells were scarlessly converted into the opposite type genes by site-specific homologous recombination, and the resulting MATB-type cells were mated at low temperature (22°C) with addition of sodium citrate with each MATA-type haploid cell to yield a MATA/MATB-type diploid strain with genetic information from both parental strains. The results of this study can be used to increase ploidy and for whole genome engineering of a yeast strain with unparalleled versatility for industrial application.

Direct Transformation of N-Protected α,β-Unsaturated γ-Amino Amides into γ-Lactams through a Base-Mediated Molecular Rearrangement.

Here, we are reporting a single-step transformation of N-protected α,β-unsaturated γ-amino amides into 5,5-disubstituted γ-lactams through a base-mediated new molecular rearrangement. In contrast to the known N- to C(O) cyclization of saturated γ-amino acids into corresponding γ-lactams, the new rearrangement involves the cyclization between N-terminal Cγ- to C-terminal amide N. The cyclization process was initiated by the migration of double bond from α,β → β,γ position. The enamine-imine tautomerization of the new β,γ-double bond and subsequent 5-exo-trig cyclization of terminal amide leads to the formation of N-protected 5,5-disubstituted γ-lactam. The structures of various γ-lactams obtained from the rearrangement were studied in single crystals. Overall, the results reported here demonstrate the facile and single-step transformation of N-protected α,β-unsaturated γ-amino amides into γ-lactams and provided an excellent opportunity to construct small-molecule peptidomimetics.

Transformation Morphisms and Time-to-Extinction Analysis That Map Therapy Duration From Preclinical Models to Patients With Tuberculosis: Translating From Apples to Oranges.

A major challenge in medicine is translation of preclinical model findings to humans, especially therapy duration. One major example is recent shorter-duration therapy regimen failures in tuberculosis. We used set theory mapping to develop a computational/modeling framework to map the time it takes to extinguish the Mycobacterium tuberculosis population on chemotherapy from multiple hollow fiber system model of tuberculosis (HFS-TB) experiments to that observed in patients. The predictive accuracy of the derived translation transformations was then tested using data from 108 HFS-TB Rapid Evaluation of Moxifloxacin in Tuberculosis (REMoxTB) units, including 756 colony-forming units (CFU)/mL. Derived transformations, and Latin hypercube sampling-guided simulations were used to predict cure and relapse after 4 and 6 months of therapy. Outcomes were compared to observations, in 1932 patients in the REMoxTB clinical trial. HFS-TB serial bacillary burden and serial sputum data in the derivation dataset formed a structure-preserving map. Bactericidal effect was mapped with a single step transformation, while the sterilizing effect was mapped with a 3-step transformation function. Using the HFS-TB REMoxTB data, we accurately predicted the proportion of patients cured in the 4-month REMoxTB clinical trial. Model-predicted vs clinical trial observations were (i) the ethambutol arm (77.0% [95% confidence interval {CI}, 74.4%-79.6%] vs 77.7% [95% CI, 74.3%-80.9%]) and (ii) the isoniazid arm (76.4% [95% CI, 73.9%-79.0%] vs 79.5% [95% CI, 76.1%-82.5%]). We developed a method to translate duration of therapy outcomes from preclinical models to tuberculosis patients.

Deterministic transformations of coherent states under incoherent operations

It is well known that the majorization condition is the necessary and sufficient condition for the deterministic transformations of both pure bipartite entangled states by local operations and coherent states under incoherent operations. In this paper, we present two explicit protocols for these transformations. We first present a permutation-based protocol which provides a method for the single-step transformation of $d$-dimensional coherent states. We also obtain generalized solutions of this protocol for some special cases of $d$-level systems. Then, we present an alternative protocol where we use $d'$-level ($d'$ $<$ $d$) subspace solutions of the permutation-based protocol to achieve the complete transformation as a sequence of coherent-state transformations. We show that these two protocols also provide solutions for deterministic transformations of pure bipartite entangled states.