Tropos Diphenylmethane-Based Phosphine-Phosphoramidite Ligands: Design, Synthesis, and Application in Catalytic Asymmetric Hydrogenation.

A series of chiral hybrid diphosphorus ligands incorporating a conformationally flexible tropos diphenylmethane-based phosphoramidite unit have been developed and evaluated in the Rh-catalyzed asymmetric hydrogenation of 2-(1-arylvinyl)anilides and α-enamides, leading to up to >99% yield and 99% enantiomeric excess. Preliminary results from comparative studies showcased the extraordinary catalytic performance of these chiral tropos phosphine-phosphoramidite ligands, with a competency essentially superior to those of well-established ligands with a regular rigid backbone.

Copper-Catalyzed Difunctionalization of Propargylic Carbonates through Tandem Nucleophilic Substitution/Boroprotonation.

Highly functionalized organic molecules are in high demand, but their preparation is challenging. Copper-catalyzed transformation of alkynyl- and allenyl-containing substrates has emerged as a powerful tool to achieve this objective. Herein, an efficient copper-catalyzed difunctionalization of propargylic carbonates through tandem nucleophilic substitution/boroprotonation has been developed, affording the formation of thiol-, selenium-, and boron-functionalized alkenes with high yield and stereoselectivity.

New P,N ligands for palladium-catalyzed asymmetric allylic substitutions.

New P,N bidentate ligands containing two chiral carbon centers were developed and applied to palladium-catalyzed asymmetric allylic substitution reactions. Good generalities with various nucleophiles, including carbon, nitrogen and oxygen containing nucleophiles, were achieved with up to 96% ee and 98% yield. This reaction provides an efficient method for the asymmetric formation of C-C, C-N and C-O bonds.

Upgrading protected areas can improve or reverse the decline in conservation effectiveness: Evidence from the Tibetan Plateau, China.

Protected areas (PAs) are considered essential for maintaining biodiversity. Several governments would like to strengthen the management levels of their PAs (as shorthand for a hierarchy in PA administrative governance) to consolidate their conservation effectiveness. This upgrade (e.

Development of spirocyclic phosphoramidite-based hybrid diphosphorus ligands for enantioselective iridium-catalyzed hydrogenation of imines.

Unsymmetrical hybrid chiral diphosphorus ligands bearing a spirocyclic phosphoramidite scaffold have been developed and successfully applied in the iridium-catalyzed asymmetric hydrogenation of imines. With this newly developed chiral iridium catalytic system, a wide range of imines including sterically hindered ones could be hydrogenated to give the corresponding optically active amines in high yields (up to >99%) and with excellent enantioselectivities (up to >99% ee). The utility of this hydrogenation has been demonstrated by the preparation of the chiral fungicide ()-benalaxyl.

Climate change mitigation potentials of biofuels produced from perennial crops and natural regrowth on abandoned and degraded cropland in Nordic countries.

Bioenergy expansion is present in most climate change mitigation scenarios. The associated large land use changes have led to concerns on how bioenergy can be sustainably deployed. Promising win-win strategies include the production of perennial bioenergy crops on recently abandoned cropland or on cropland prone to land degradation, as perennial crops typically reduce soil erosion rates.

Palladium-catalysed construction of butafulvenes.

Butafulvene is a constitutional isomer of benzene, comprising a cyclobutene skeleton bearing two exocyclic conjugated methylene units. As a result of the intrinsic high strain energy and anti-aromaticity, the preparation of butafulvene compounds has been a fundamental issue for the development of butafulvene chemistry. Here an efficient palladium-catalysed coupling protocol involving propargylic compounds has been developed, providing a solid and versatile strategy for the rapid assembly of symmetric butafulvene derivatives.

Highly Enantioselective Iridium-Catalyzed Hydrogenation of -Amidophenyl Ketones Enabled by 1,2-Diphenylethylenediamine-Derived P,N,N-Ligands with Tertiary Amine Terminus.

A readily available and highly modular class of chiral P,N,N-ligands based on a structurally flexible nonchiral phosphine-amine framework with an optically active 1,2-diphenylethylenediamine unit bearing a tertiary amine terminus as the chiral source have been developed and successfully applied in the Ir-catalyzed asymmetric hydrogenation of -amidophenyl ketones. These tridentate P,N,N-ligands exhibited excellent activity, enantioselectivity, and substrate tolerance, thus furnishing various optically active -amidobenzhydrols in up to 99% yields and with >99% ee. The utility of this protocol has been proven by synthetically diverse product transformation and highly enantioselective production of a rice plant growth regulator, ()-inabenfide.

Intramolecular Copper-Catalyzed Asymmetric Propargylic [4 + 2]- Cycloaddition toward Optically Active Tetrahydroisoindolo[2,1-]quinoxalines.

An intramolecular Cu-catalyzed asymmetric propargylic [4 + 2] cycloaddition of bis--nucleophile-functionalized propargylic esters has been realized in the support of a chiral tridentate N-ligand, (,)-Pybox-diOAc, leading to chiral tetrahydroisoindolo[2,1-]quinoxalines in high yields and with good to excellent enantioselectivities. The reaction features high efficiency, simplicity, and broad substrate scope, thus providing a powerful and concise strategy for stereoselective access to optically active polycyclic heterocycle frameworks that are otherwise difficult to synthesize.

Bicyclic Bridgehead Phosphoramidite-Based Hybrid Diphosphorus Ligands: Design, Synthesis, and Application in Catalytic Asymmetric Hydrogenation.

A strategy for chiral ligand design has been developed that allows for incorporation of an achiral bicyclic bridgehead phosphoramidite to generate a class of hybrid diphosphorus ligands for high activity and asymmetric control. Using this concept, a series of chiral phosphine-phosphoramidite ligands bearing the sole chirality at the ligand backbone have been prepared and successfully employed in the Rh-catalyzed asymmetric hydrogenation of 2-vinylanilides for the synthesis of optically active anilines bearing an -tertiary benzylic stereocenter.

Sensitivity and future exposure of ecosystem services to climate change on the Tibetan Plateau of China.

Context: Climate change has imposed tremendous impacts on ecosystem services. Recent attempts to quantify such impacts mainly focused on a basin or larger scale, or used limited time periods that largely ignore observations of long-term trends at a fine resolution, thereby affecting the recognition of climate change's effect on ecosystem services.

Objectives: This study conducts a detailed and spatially explicit recognition of climate change's effect on ecosystem services and provides an intuitive map for decision-making and climate change adaptation planning.

Enantioselective Copper-Catalyzed [3 + 3] Cycloaddition of Tertiary Propargylic Esters with 1-Pyrazol-5(4)-ones toward Optically Active Spirooxindoles.

A copper-catalyzed enantioselective [3 + 3] cycloaddition of 3-ethynyl-2-oxoindolin-3-yl acetates with 1-pyrazol-5(4)-ones for the construction of optically active spirooxindoles bearing a spiro all-carbon quaternary stereocenter has been realized. With a combination of Cu(OTf) and chiral tridentate ketimine P,N,N-ligand as the catalyst, the reaction displayed broad substrate scopes, good yields, and high enantioselectivities. This represents the first catalytic asymmetric propargylic cycloaddition with tertiary propargylic esters as the bis-electrophiles for access to chiral spirocyclic frameworks.

The catalyst-free decarboxylative dearomatization of isoquinolines with β-keto acids and sulfonyl chlorides in water: access to dihydroisoquinoline derivatives.

An efficient and concise catalyst-free one-pot synthetic protocol for obtaining dihydroisoquinoline derivatives has been developed via the three-component condensation of isoquinolines with β-keto acids and sulfonyl chlorides. This transformation involving decarboxylative dearomatization worked well under mild and water-mediated conditions. The protocol tolerates diverse functional groups, furnishing the dihydroisoquinoline products in good to excellent yields.

The unequal contribution to global energy consumption along the supply chain.

Reducing fossil fuel consumption is a top priority option for climate change mitigation, which requires collaborations of partners along the supply chain, such as energy suppliers, energy consumers and final consumers of goods and services. A comprehensive analysis of fossil fuel consumption is useful for policymakers to reduce demand but still absent. This study explores the national contribution to global energy consumption from different perspectives in the global supply chain and is designed to complement current energy reduction policies.

Predominant regional biophysical cooling from recent land cover changes in Europe.

Around 70 Mha of land cover changes (LCCs) occurred in Europe from 1992 to 2015. Despite LCCs being an important driver of regional climate variations, their temperature effects at a continental scale have not yet been assessed. Here, we integrate maps of historical LCCs with a regional climate model to investigate air temperature and humidity effects.

Copper-Catalyzed Asymmetric Propargylic Alkylation with Oxindoles: Diastereo- and Enantioselective Construction of Vicinal Tertiary and All-Carbon Quaternary Stereocenters.

A copper-catalyzed asymmetric propargylic alkylation of propargylic acetates with 3-substituted oxindoles for the stereoselective construction of vicinal tertiary and all-carbon quaternary stereocenters in a 3,3-disubstituted oxindole skeleton has been realized. The reaction proceeded smoothly under the catalysis of Cu(MeCN)PF combined with a chiral tridentate ferrocenyl P,N,N ligand, leading to a broad range of optically active 3,3-disubstituted oxindoles in high yields and with excellent diastereo- and enantioselectivities.

Highly Diastereo- and Enantioselective Ir-Catalyzed Hydrogenation of 2,3-Disubstituted Quinolines with Structurally Fine-Tuned Phosphine-Phosphoramidite Ligands.

A highly diastereo- and enantioselective Ir-catalyzed hydrogenation of unfunctionalized 2,3-disubstituted quinolines, especially 3-alkyl-2-arylquinolines, has been realized. The success of this hydrogenation is ascribed to the use of a structurally fine-tuned chiral phosphine-phosphoramidite ligand with a ()-3,3'-dimethyl H-naphthyl moiety and ()-1-phenylethylamine backbone. The hydrogenation displayed broad functional group tolerance, thus furnishing a wide range of optically active 2,3-disubstituted tetrahydroquinolines in up to 96% ee and with perfect -diastereoselectivity.

Rh-Catalyzed Asymmetric Hydrogenation of ()-β-Phosphorylated Enamides: Highly Enantioselective Access to β-Aminophosphines.

A catalytic asymmetric hydrogenation of β-phosphorylated enamides for enantioselective access to optically active β-aminophosphine derivatives is reported. Critical to the success of this method was the employment of rhodium catalysis in concert with an unsymmetrical hybrid chiral phosphine-phosphoramidite ligand. A wide range of aromatic β-phosphorylated enamides could be hydrogenated in full conversion and with perfect enantioselectivity even at low catalyst loadings (S/C = 1000).

Diastereo- and Enantioselective Copper-Catalyzed Decarboxylative Ring-Opening [3 + 2] Annulation of Tertiary Propargylic Carbamates through Regioselective α-Attack of γ-Butenolides.

A copper-catalyzed regio-, diastereo-, and enantioselective decarboxylative ring-opening [3 + 2] annulation of tertiary propargylic carbamates with γ-butenolides for the synthesis of optically active pyrrolidinones has been realized. The reaction proceeded through regioselective α-attack of γ-butenolide and generated highly congested vicinal tertiary and all-carbon quaternary stereocenters in pyrrolidinone scaffolds, featuring high stereoselective induction and broad functional group tolerance. Critical to the successful development of this method was the employment of copper catalysis in concert with a diPh-Pybox ligand.

Traceless-Activation Strategy for Rh-Catalyzed Csp-H Arylation of Coumarins.

A traceless-activation strategy for the synthesis of 4-arylchroman-2-ones via a Rh(III)-catalyzed C-H activation of 2-arylpyridines and subsequent conjugated/decarboxylative addition to coumarin-3-carboxylic acids has been reported. The carboxyl group at C3 position of coumarin proved to be crucial to realize the reaction, which is spontaneously removed after the reaction by the release of CO. The reaction displayed good substrate tolerance and gave various 4-arylchroman-2-ones in up to 90% yield.

Copper-catalyzed, silver-mediated formal [3+2] cycloaddition of simple alkynes with β-ketoesters through propargylic C(sp)-H functionalization.

A copper-catalyzed propargylic [3+2] cycloaddition of simple alkynes with β-ketoesters through the propargylic C(sp3)-H functionalization has been realized. Under catalysis by CuI in combination with 1,10-phenanthroline hydrate as the ligand and Ag2CO3 as a bifunctional reagent (oxidant and base), the reaction proceeds smoothly with a broad substrate scope, thus providing a variety of highly functionalized furans in moderate to high yields. This represents the first successful example of the catalytic propargylic cycloaddition of simple alkynes with bisnucleophiles based on the propargylic C(sp3)-H functionalization strategy.

Copper-catalyzed propargylic [3+3] cycloaddition with 1H-pyrazol-5(4H)-ones: enantioselective access to optically active dihydropyrano[2,3-c]pyrazoles.

A copper-catalyzed asymmetric propargylic [3+3] cycloaddition with 1H-pyrazol-5(4H)-ones as C,O-bisnucleophiles through the desilylation-activated strategy has been developed. With the catalysis of Cu(OAc)2·H2O in combination with a chiral tridentate P,N,N-ligand, the reaction displayed a broad substrate scope, and thus provided a variety of chiral dihydropyrano[2,3-c]pyrazoles in high yields and with excellent enantioselectivities (up to 96% ee).

Contribution of forest wood products to negative emissions: historical comparative analysis from 1960 to 2015 in Norway, Sweden and Finland.

Background: Forests and forest products can significantly contribute to climate change mitigation by stabilizing and even potentially decreasing the concentration of carbon dioxide (CO) in the atmosphere. Harvested wood products (HWP) represent a common widespread and cost-efficient opportunity for negative emissions. After harvest, a significant fraction of the wood remains stored in HWPs for a period that can vary from some months to many decades, whereas atmospheric carbon (C) is immediately sequestered by vegetation re-growth.

A multi-electron transfer ferrocene derivative positive redox moiety with improved solubility and potential.

Rational molecular structure modification towards high performance redox couples attracts great concern. A ferrocene derivative N-(pyridin-2-ylmethylene)-1-(2-(diphenylphosphino) ferrocenyl) ethanamine (FeCp2PPh2RCN) with improved solubility and potential as well as multi-electron transfer behavior is designed and fabricated. Benefitting from the high operating current density and capacity of the battery, FeCp2PPh2RCN demonstrates promising prospects as a positive redox moiety.

Decarboxylation-promoted Pd-catalyzed asymmetric propargylic [3 + 2] annulation for the enantioselective construction of a quaternary stereocenter in 2,3-dihydrofurans.

The enantioselective construction of a quaternary stereocenter in 2,3-dihydrofuran frameworks has been realized via the palladium-catalyzed asymmetric [3 + 2] cycloaddition of tertiary propargylic carbonates with β-ketoesters enabled by a chiral ferrocene/benzimidazole-based bidentate P,N-ligand. The reaction was significantly promoted by loss of CO to irreversibly form π-propargylpalladium or allenylpalladium intermediates. This protocol features a good tolerance of functional groups in both tertiary propargylic carbonates and β-ketoesters, thereby delivering a variety of highly functionalized chiral 2,3-dihydrofurans bearing a quaternary stereocenter at the 2-position and an exocyclic double bond at the 3-position in good chemical yields and high enantioselectivities (up to 98% ee).