Direct synthesis of C3-alkynyl pyrroloindolines from tryptamines via a visible-light-induced radical cascade reaction.

A visible-light-induced radical cascade reaction for the direct alkynylation of tryptamines with alkynyl sulfones was developed, affording a series of C3-alkynyl pyrroloindolines in excellent yields. This method features readily available substrates, good functional group tolerability, and scalability. C3-alkynyl pyrroloindolines show great potential as useful building blocks in the preparation of complex and valuable pyrroloindoline alkaloids.

Photochemical Synthesis of Indolocarbazoles through Tandem Indolization/Dimerization/Mannich Cyclization from Allenes.

Indolocarbazole alkaloids and their derivatives were discovered to have potent protein kinase and topoisomerase I inhibitory activities. Disclosed herein is the photochemical synthesis of the indolocarbazole ring system from N-allenyl-2-iodoanilines. The tandem protocol included visible-light-mediated 5-exo-trig radical cyclization and subsequent radical dimerization, followed by acid-promoted deprotection and intramolecular Mannich cyclization. This strategy showed exceptional functional group tolerance and was successfully applied in the concise synthesis of natural products tjipanazoles B and D.

Dissimilar evolution of soil dissolved organic matter chemical properties during revegetation with arbor and shrub in desertified land of the Mu Us Desert.

The chemistry of dissolved organic matter (DOM) in soil determines its bioavailability and is crucial to soil nutrient cycling and vegetation restoration. However, the response of DOM to revegetation in degraded ecosystems is not well understood. This study analyzed soil chronosequences from semifixed (SF) sand in the Mu Us Desert, China that was afforested with arbor and shrub 23-54 years ago. The DOM organic composition and chemical properties were investigated by fluorescence excitation-emission matrix spectrophotometry and UV-visible spectroscopy. As the revegetation progressed, DOM concentration at 0-20 cm continually increased. In arbor land, the DOM was mainly influenced by dissolved organic carbon, and the average concentration significantly increased from 67.5 to 203.2 mg C•kg-1. In the shrubland, changes in DOM were mainly influenced by dissolved organic nitrogen, with the average concentration significantly increasing from 3.7 to 8.9 mg N•kg-1. Arbor afforestation significantly increased the proportion of hydrophobic humic-like components (C1), with a decline in bioactive tryptophan-like components (C3) and higher DOM molecular complexity (i.e., higher molecular weight, aromaticity, and degree of humification). However, in shrubland, the proportions of C1 and C3 were significantly lower than those in arbor forest soil, with DOM molecular complexity slightly increased, and DOM tended to become more bioavailable over time. Linear regression analysis indicated that DOM rich in carbon had a high molecular complexity, while DOM rich in nitrogen is more bioavailable. These findings reveal a dissimilar evolution in the DOM composition and chemistry in the two forest types throughout the SF sand revegetation period. The DOM under arbor forest was more stable and conducive to soil organic matter sequestration, while the DOM under shrub forest contained more bioactive substances and was more favorable for nutrient cycling.

Influence of arbuscular mycorrhizal fungi on selenium uptake by winter wheat depends on the level of selenate spiked in soil.

Selenium (Se) deficiency has been a public health concern for years. Arbuscular mycorrhizal fungi (AMF) play an essential role in improving Se uptake in crops, but related mechanisms still remain unclear. To explore the influence of AMF on uptake of Se in winter wheat, a pot experiment was conducted to inoculate wheat with Funneliformis mosseae (F.m) or not under different levels of selenate in soil. The present results indicated that inoculation of F.m significantly (p < 0.05) increased Se concentration in shoots and roots of wheat under low level of selenate (≤5.0 mg kg-1) treatments, while the contrary pattern was recorded under high level of selenate (15 and 20 mg kg-1) treatments. Moreover, inoculation of F.m significantly increased concentration of available Se in soil by 4.68-34.05%. Under selenate ≤5 mg kg-1 treatments, the expression of TaeSultr1;1 and TaeSultr1;3 in roots of mycorrhizal wheat was significantly up-regulated by 3.06-5.53 and 0.63-5.12 times, while reached saturation under selenate >5 mg kg-1 treatments. In addition, partial least squares path modeling (PLS-PM) showed that inoculation of AMF directly affected the expression of sulfate transporter and that both sulfate transporter and soil Se fractions played a significant positive effect on plant Se content. The present study indicated that AMF on Se concentration in winter wheat depends on the level of selenate spiked in soil and added to our understanding of the functions and applications of AMF on crop Se absorption.

Acylation of Arenes with Aldehydes through Dual C-H Activations by Merging Photocatalysis and Palladium Catalysis.

An acylation of arenes with aldehydes through dual C-H activations at room temperature is reported. The acylation was initiated by phenanthraquinone-catalyzed hydrogen atom transfer from aldehyde under visible light irradiation. The aldehyde-derived acyl radical merged with palladium-catalyzed activation of arenes to afford the cross coupling products.

A photoexcited halogen-bonded EDA complex of the thiophenolate anion with iodobenzene for C(sp3)-H activation and thiolation.

Thiophenol was discovered to form an EDA complex with iodobenzene through halogen bonding interactions upon treatment with KOH. A direct photochemical thiolation of C(sp3)-H bond-containing etheric, allylic, and benzylic substrates with thiophenol was developed. The reaction proceeded on the basis of the in situ generation of a thiyl radical and aryl radical through single electron transfer between the photoexcited thiophenolate anion and aryl iodide EDA complex. Then a C(sp3) centred-radical was formed by aryl radical-mediated hydrogen atom transfer and the thiolation products were delivered via a radical-radical cross-coupling with the thiyl radical.

Correction: A photoexcited halogen-bonded EDA complex of the thiophenolate anion with iodobenzene for C(sp3)-H activation and thiolation.

[This corrects the article DOI: 10.1039/D1SC03667J.].

Meta-analysis of modified Blumgart anastomosis and interrupted transpancreatic suture in pancreaticojejunostomy after pancreaticoduodenectomy.

Postoperative pancreatic fistula (POPF) remains the main cause of surgery related mortality after pancreaticoduodenectomy. Various pancreatoenteric anastomosis methods have been developed to reduce the POPF rate. However, the optimum choice has not been clarified. A literature search is performed in electronic databases, including PubMed, Medline, Embase, CNKI and the Cochrane Library. Studies comparing modified Blumgart anastomosis with interrupted transpancreatic suture are included in this meta-analysis. Grade B/C POPF, overall POPF rate and overall sever complication rate (Clavien-Dindo classification IIIa or more) are measured as primary outcomes. Revman 5.3 was used to perform the analysis. Five retrospective comparative studies and 1 randomized controlled trial with a total number of 1409 patients are included in our analysis. Meta-analysis revealed that modified Blumgart anastomosis is associated with lower rate of grade B/C POPF [Odds Ratio (OR) 95% confidence interval (CI),0.32 (0.12-0.84); P = 0.02] and intra-abdominal abscess [OR 95%CI, 0.43 (0.29-0.65); P < 0.01] comparing with interrupted transpancreatic suture. However, this procedure could not reduce overall POPF [OR 95%CI,0.70 (0.34-1.44); P = 0.34] and overall sever complication rate [OR 95%CI,0.91 (0.48-1.72); P = 0.77]. At current level of evidence, modified Blumgart anastomosis is superior to interrupted transpancreatic suture in terms of grade B/C POPF and intra-abdominal abscess. However, high-grade evidence will be necessary to confirm these results.

Succession of fungal dynamics and their influence on physicochemical parameters during pig manure composting employing with pine leaf biochar.

The effects of pine leaf biochar (PLB) on fungal community during pig manure composting were investigated. Five different doses of PLB [0% (T1), 2.5% (T2), 5% (T3), 10% (T4) and 15% (T5)] were mixed with mixture of pig manure and sawdust (2:1) for 50 days of composting. The present results indicated that fungal diversity increased more obvious in biochar amendment treatments than control (T1) and that the highest was recorded in T4 treatment. Basidiomycota, Ascomycota and Mucoromycota were the most three abundant phyla in all the treatments, while Heterobasidion, Pezoloma, Mucor, Geastrum, Talaromyces and Cystofilobasidium were the richness genera. In addition, network analysis indicated that fungal community abundance was significantly (p < 0.05) associated with temperature, pH, CO2 and CH4 emission and the seed germination index. In summary, the 10% PLB amendment (T4) was a potential option to strengthen fungal diversity and improve the composting efficiency as well as compost quality.

Impact of pine leaf biochar amendment on bacterial dynamics and correlation of environmental factors during pig manure composting.

The influence of pine leaf biochar (PLB) amendment on bacterial community succession and its correlation with physic-chemical parameters during pig manure (PM) composting was evaluated. The five different dosages of PLB [at 0% (T1), 2.5% (T2), 5% (T3), 10% (T4) and 15% (T5)] mixed with initial composting mass were conducted to composting for 50 days. The present study indicated that bacterial diversity was significantly (p < 0.05) higher in PLB amended treatments than the control, but T4 treatment showed the highest among the all PLB applied treatment. Firmicutes, Actinobacteria, Proteobacteria and Bacteroidete were four most abundant phyla of all the treatments. Furthermore, redundancy analysis showed that the bacterial community were significantly (p < 0.05) positively correlated with temperature, pH, TOC, CO2 and NH3 emissions, while they were negatively correlated with the N2O and CH4 emission. Overall, the results suggested that the addition of 10% PLB (T4 treatment) was a potential option to enhance the composting efficiency with significantly greater abundance of bacterial community and finally improved the compost quality.

Retro-biosynthetic construction of corynanthe alkaloid skeletons from rhynchophylline alkaloids.

Rhynchophylline alkaloids are bio-synthesized from corynanthe alkaloids via an oxidative rearrangement. We demonstrate here that corynanthe alkaloids could be generated from rhynchophylline alkaloids in a retro-biosynthetic manner via a Wagner-Meerwein rearrangement. A series of corynanthe analogues were afforded with good functional group tolerance and satisfactory yields.

Enantioselective Total Synthesis of (+)-Flavisiamine†F via Late-Stage Visible-Light-Induced Photochemical Cyclization.

The structural features Kopsia alkaloids, in particular multiple all-carbon quaternary stereocenters in a caged and strained polycyclic skeleton, poses particular challenges for enantioselective total synthesis. Herein, we reported the first total synthesis of (+)-flavisiamine F. The synthetic approach involved a room-temperature Overman rearrangement for introducing the chiral amine at C21, a TMS-promoted ketal Claisen rearrangement for constructing the all-carbon quaternary stereocenter at C20, and a late-stage visible-light-induced photochemical cyclization for establishing the all-carbon quaternary stereocenter at C7.

Combinations of soil properties, carbon inputs and climate control the saturation deficit dynamics of stable soil carbon over 17-year fertilizaiton.

The soil organic carbon (SOC) saturation deficit (Csd) of silt and clay fractions represents the potential for SOC sequestration in a stable form and can influence organic C stabilization efficiency. Little is known, however, about temporal changes of stable soil Csd and how it is affected by soil properties, climate and C inputs. We investigated the temporal changes in the Csd of fine fractions (<53 µm) and examined the factors controlling these changes at three dry-land sites with 17-year fertilizer management histories in China. The rates of change in the stable soil Csd under manure treatments varied from -0.72 to -1.24% yr-1 after 17 years of fertilization, indicating that stable C levels under manure treatments were significantly higher than those under other treatments. Stable soil Csd was controlled by a combination of soil properties, temperature, and C inputs at all sites, and the higher variance of Csd of fine fractions can be explained by the soil properties (up to 50%). Furthermore, the quantity of C inputs was the most influential variable for stable soil Csd. These results revealed key controls on stable C sequestration potential and indicated the need to develop management strategies to promote stable C sequestration under long-term intensive fertilization.

Enantioselective Radical Cyclization of Tryptamines by Visible Light-Excited Nitroxides.

Nitroxides can absorb both ultraviolet (UV) and visible light, and their electron can be excited from the π-bonding orbital to the antibonding π* orbital or the n-bonding orbital to the antibonding π* orbital, respectively. Despite the reported UV-induced hydrogen atom transfer (HAT) process, the potential of nitroxides for visible light-excited photosynthesis is underexplored. Here we demonstrate that nitroxide can convert indole to its radical through a visible light-induced HAT process. A chiral phosphoric acid-catalyzed cyclization of the in situ-formed imine radical, followed by trapping by another molecule of nitroxide, provides the product in high yield and enantioselectivity. To highlight the novelty and efficiency of this strategy, an asymmetric total synthesis of natural product (-)-verrupyrroloindoline was accomplished in 5 steps.

Evaluation of soil quality along two revegetation chronosequences on the Loess Hilly Region of China.

Vegetation restoration has been widely implemented to control soil degradation, reduce soil erosion, and improve soil quality. It is vital to understand the mechanisms affecting soil quality in soil restoration processes and to determine an appropriate recover pattern for soil restoration. Thus, a soil quality index was developed using integrated approach to assess soil quality after vegetation restoration in this study. Soil samples were collected from two restoration pathways (afforestation by Robinia pseudoacacia L. and natural recovery of abandoned farmland) with ages sequence of 0, 17,27 and 42years old at two soil depths (0-10 and 10-20cm) to measure soil physicochemical and biological properties on the Loess Hilly Region of China, China. The results showed that soil quality index (SQI) was developed based on microbial biomass carbon (MBC), fine particles (FP), and total phosphorus (TP). The MBC, which had the fastest increase rate than TP and FP, had the highest contribution to the final SQI and these contributions increased with recovery age. The MBC values were higher in Robinia pseudoacacia L. than in abandoned land sites at all recovery ages with greater increases along with restoration age. The SQI values significantly increased with increasing restoration age up to 27years (P<0.05). After 27years, SQI values for the AL sites remained stable, while SQI values for RP sites continually improved with increasing restoration age. In addition, SQI values were higher for RP sites than for AL sites for all restoration ages.

Moschamine-Related Indole Alkaloids.

Moschamine-related alkaloids originate mainly from feruloylserotonin by cyclization or dimerization. This review provides a comprehensive overview on the achievements in the field of moschamine-related alkaloids. In the isolation part, a detailed structural characterization of moschamine-related alkaloids is followed by their spectral data. Besides the well-known antioxidative activities, other screened biological properties are also outlined. Since their isolation, different protocols have been developed to synthesize these alkaloids. The synthetic part is organized according to the different synthetic methodologies for the formation of key structural elements.

Biomimetic Synthesis of Moschamine-Related Indole Alkaloids via Iron-Catalyzed Selectively Oxidative Radical Coupling.

An iron-catalyzed oxidative radical coupling reaction was developed to selectively construct indolofuran or bisphenolic indole cores, which exist in two types of moschamine-related indole alkaloids. Both (+)-decursivine and 4,4″-bis(N-feruloyl)serotonin were biomimetically synthesized by using coupling reactions. The proposed reassignment of the structure of montamine as 4,4″-bis(N-feruloyl)serotonin was excluded.

Surface coal mine land reclamation using a dry flue gas desulfurization product: Short-term and long-term water responses.

Abandoned coal-mined lands are a worldwide concern due to their potential negative environmental impacts, including erosion and development of acid mine drainage. A field study investigated the use of a dry flue gas desulfurization product for reclamation of abandoned coal mined land in USA. Treatments included flue gas desulfurization product at a rate of 280 Mg ha(-1) (FGD), FGD at the same rate plus 112 Mg ha(-1) yard waste compost (FGD/C), and conventional reclamation that included 20 cm of re-soil material plus 157 Mg ha(-1) of agricultural limestone (SOIL). A grass-legume sward was planted after treatment applications. Chemical properties of surface runoff and tile water (collected from a depth of 1.2m below the ground surface) were measured over both short-term (1-4 yr) and long-term (14-20 yr) periods following reclamation. The pH of surface runoff water was increased from approximately 3, and then sustained at 7 or higher by all treatments for up to 20 yr, and the pH of tile flow water was also increased and sustained above 5 for 20 yr. Compared with SOIL, concentrations of Ca, S and B in surface runoff and tile flow water were generally increased by the treatments with FGD product in both short- and long-term measurements and concentrations of the trace elements were generally not statistically increased in surface runoff and tile flow water over the 20-yr period. However, concentrations of As, Ba, Cr and Hg were occasionally elevated. These results suggest the use of FGD product for remediating acidic surface coal mined sites can provide effective, long-term reclamation.

Copper-mediated dimerization to access 3a,3a'-bispyrrolidinoindoline: diastereoselective synthesis of (+)-WIN 64821 and (-)-ditryptophenaline.

A copper-mediated cyclization and dimerization of tryptamine or tryptophan was developed to generate a C2-symmetry C3(sp(3))-C3(sp(3)) bridge with two contiguous stereogenic quaternary carbons in one step. Impressively, the ratio between exo and endo cyclization products varies when different protecting groups of Nb are utilized. This dimerization reaction could be conducted in gram scale. With this dimerization method, both endocyclotryptophan (+)-WIN 64821 and exocyclotryptophan (-)-ditryptophenaline were synthesized in 5 steps.

Copper-catalyzed radical cyclization to access 3-hydroxypyrroloindoline: biomimetic synthesis of protubonine A.

An unprecedented copper-catalyzed intramolecular radical cyclization was developed for the synthesis of 3-hydroxypyrroloindoline skeletons in excellent yields. The 3-hydroxyl group was introduced by trapping the radical intermediate with molecular oxygen or TEMPO. This process represents a unique radical oxidation pathway for tryptamine/tryptophan derivatives and allows a rapid biomimetic synthesis of natural product protubonine A.