Characterization of Fusarium species causing head blight of highland barley (qingke) in Tibet, China.

Most of the research on the characterization of Fusarium species focused on wheat, barley, rice, and maize in China. However, there has been limited research in highland barley (qingke). Recently, Fusarium head blight (FHB) of qingke was recently observed in Tibet, China, especially around the Brahmaputra River. To gain a better understanding of the pathogens involver, 201 Fusarium isolates were obtained from qingke samples in 2020. Among these isolates, the most abundant species was F. avenaceum (45.3 %), followed by F. equiseti (27.8 %), F. verticillioides (13.9 %), F. acuminatum (9.0 %), F. flocciferum (3.5 %), and F. proliferatum (0.5 %). The distribution of Fusarium species varied along the Brahmaputra River, with F. avenaceum being predominant in the midstream and downstream regions, while F. equiseti was more common in the upstream region. Chemical analyses of all the isolates revealed the production of different mycotoxins by various Fusarium species. It was found that enniatins were produced by F. acuminatum, F. avenaceum, and F. flocciferum, beauvericin (BEA) and fumonisins were produced F. proliferatum and F. verticillioides, and zearalenone (ZEN) and nivalenol (NIV) were produced by F. equiseti. Pathogenicity test showed that F. avenaceum was more aggressive in causing FHB compared to F. acuminatum, F. equiseti, and F. flocciferum. The disease severity, measured by the area under the disease progress curve (AUDPC), was significantly positively (P < 0.01) correlated with the concentration of total toxins produced by each species. Furthermore, all the Fusarium strains which were used for pathogenicity test were susceptible to carbendazim, and the 50 % effective concentration (EC50) ranged from 0.406 µg/mL to 0.673 µg/mL with an average EC50 of 0.551 ± 0.012 µg/mL.

Two Undescribed Germacrane-Type Sesquiterpenoids from Salvia cavaleriei var. simplicifolia Stib. and Their Anti-Alzheimer's Disease Activity.

Two undescribed germacrane-type sesquiterpenoids, salcasins A (1) and B (2), together with three known compounds (3-5) were isolated and identified from the whole plant of Salvia cavaleriei var. simplicifolia Stib. The structures of the undescribed compounds were elucidated on the basis of spectroscopic methods, such as HR-ESI-MS, 1D and 2D NMR data. The relative configurations of 1 and 2 were established by analyzing their NOESY spectra as well as by 13C NMR calculations with DP4+ probability analyses. The absolute configurations of 1 and 2 were determined by comparing experimental and calculated ECD spectra. Furthermore, the in vivo anti-Alzheimer's disease activities of 1-5 were evaluated using Caenorhabditis elegans AD pathological model. Among all isolated compounds, salcasin A (1) significantly delayed AD-like symptoms of worm paralysis, which may be a potential anti-AD candidate agent.

Dynamic lymphocyte-CRP ratio as a predictor: a single-centre retrospective study on disease severity and progression in adult COVID-19 patients.

OBJECTIVE: To assess the efficacy of dynamic changes in lymphocyte-C-reactive protein ratio (LCR) on differentiating disease severity and predicting disease progression in adult patients with Coronavirus disease 2019 (COVID-19). METHODS: This single-centre retrospective study enrolled adult COVID-19 patients categorized into moderate, severe and critical groups according to the Diagnosis and Treatment of New Coronavirus Pneumonia (ninth edition). Demographic and clinical data were collected. LCR and sequential organ failure assessment (SOFA) score were calculated. Lymphocyte count and C-reactive protein (CRP) levels were monitored on up to four occasions. Disease severity was determined concurrently with each LCR measurement. RESULTS: This study included 145 patients assigned to moderate (n = 105), severe (n = 33) and critical groups (n = 7). On admission, significant differences were observed among different disease severity groups including age, comorbidities, neutrophil proportion, lymphocyte count and proportion, D-Dimer, albumin, total bilirubin, direct bilirubin, indirect bilirubin, CRP and SOFA score. Dynamic changes in LCR showed significant differences across different disease severity groups at different times, which were significantly inversely correlated with disease severity of COVID-19, with correlation coefficients of -0.564, -0.548, -0.550 and -0.429 at four different times. CONCLUSION: Dynamic changes in LCR can effectively differentiate disease severity and predict disease progression in adult COVID-19 patients.

Ethyl caffeate attefnuates Aß-induced toxicity in Caenorhabditis elegans AD models via the insulin/insulin-like growth factor-1 signaling pathway.

The pathogenesis of Alzheimer's disease (AD), a multifactorial progressive neurodegenerative disease associated with aging, is unclear. Ethyl caffeate is a plant polyphenol that has been reported to have neuroprotective effects, but the mechanisms by which it acts are unclear. In this study, for the first time, we investigated the molecular mechanism of its anti-AD properties using the Caernorhabditis elegans model. The results of our experiments showed that ethyl caffeate delayed the paralysis symptoms of CL4176 to a different extent and reduced the exogenous 5-hydroxytryptophan-induced paralysis phenotype. Further studies revealed that ethyl caffeate lowered Aß plaques and depressed the expression of Aß monomers and oligomers, but did not influence the mRNA levels of Aß. Moreover, it was able to bring paraquat-induced ROS levels down to near-standard conditions. Real-time quantitative PCR experiment showed a significant upregulation of the transcript abundance of daf-16, skn-1 and hsf-1, key factors associated with the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway (IIS), and their downstream genes sod-3, gst-4 and hsp-16.2. It was further shown that ethyl caffeate activated the translocation of DAF-16 and SKN-1 from the cytoplasm to the nucleus and enhanced the expression of sod-3::GFP, gst-4::GFP and hsp-16.2::GFP in transgenic nematodes. This meant that the protection against Aß toxicity by ethyl caffeate may be partly through the IIS signaling pathway. In addition, ethyl caffeate suppressed the aggregation of polyglutamine proteins in AM141, which indicated a potential protective effect against neurodegenerative diseases based on abnormal folding and aggregation of amyloid proteins. Taken together, ethyl caffeate is expected to develop as a potential drug for the management of AD.

Highly oxygenated germacrane-type sesquiterpenoids from the whole plant of Salvia cavaleriei H.Lév. and their biological activities.

The entire plant Salvia cavaleriei H.Lév. (Lamiaceae) is used as a traditional Chinese herbal medicine. Its leaves are edible, and the flowers can be soaked in water to make a health-care tea. In an effort to find natural bioactive chemical components, twelve undescribed germacrane-type sesquiterpenoids, salcavalins A-L, were isolated from the whole plant of S. cavaleriei and were identified as analogs. This is the first study to isolate highly oxygenated germacrane-type sesquiterpenoids from this plant. The structures of these undescribed compounds were elucidated by various spectroscopic methods, and their absolute configurations were confirmed by single-crystal X-ray diffraction analysis with Cu Kα radiation and electronic circular dichroism calculations. The biological activity of these undescribed compounds on the production of tumor necrosis factor-alpha in lipopolysaccharide induced NR8383 cells was evaluated, and salcavalins I and K showed anti-inflammatory activity to some extent. Salcavalins A-C, F and L were found to be neuroprotective with antiparkinsonic potential in a nematode (Caenorhabditis elegans) model. In addition, salcavalins F and I displayed marked phytotoxic activity against radish seeds at a low concentration of 50 ppm. Our findings provide scientific justification to show that bioactive sesquiterpenoids from the edible herb have anti-inflammatory in vitro, neuroprotective and phytotoxic activities.

Antimicrobial diterpenoids from the leaves and twigs of Croton kongensis Gagnepain.

Croton kongensis Gagnepain. belongs to the genus Croton, the Euphorbiaceae family, mainly distributed in Hainan and southern Yunnan, China. The aim of present study was to acquire secondary metabolites of the ethanol extract obtained from the leaves and twigs of C. kongensis. Three new abietane-type diterpenoids, crokongenolides A-C (1-3), together with seven known diterpenoids (4-10), were isolated from the leaves and twigs of C. kongensis. The structures of the new compounds were determined by extensive spectroscopic methods (1D and 2D NMR, IR, and HRESIMS), and their absolute configurations were confirmed by single-crystal X-ray diffraction analysis or electronic circular dichroism (ECD) calculations. The absolute configuration of 4 was determined for the first time by single-crystal X-ray diffraction analysis with Cu-Kα irradiation. Some compounds were evaluated for their antimicrobial properties by assessing their inhibitory effects on Staphylococcus aureus, Candida albicans, and Escherichia coli. Compound 10 showed significant antimicrobial activity against S. aureus with MIC value of 1.56 µg/ml.

Bioactive diterpenoids and sesquiterpenoids with different skeletons from Salvia digitaloides Diels.

Salvia has been regarded as a beneficial healing herb in ancient Egypt, Rome and Greece, and is listed as an official medicine in the pharmacopoeias of many countries worldwide. Currently, Salvia is widely used to flavor and preserve food. Here, two undescribed norabietane-type diterpenoids, sadigitaloides A and B, two undescribed germacrane-type sesquiterpenoids, sadigitaloides C and D, five undescribed guaiane-type sesquiterpenoid lactones, sadigitaloides E-I, two undescribed noreudesmane-type sesquiterpenoids, sadigitaloides J and K, one known diterpenoid, three known sesquiterpenoids, and three other types of known compounds were isolated from the 95% ethanol extract of the whole plants of Salvia digitaloides. Their structures and absolute configurations were characterized using 1D and 2D NMR spectroscopic techniques, electronic circular dichroism (ECD) calculations, HRESIMS experiments, and single-crystal X-ray diffraction analysis. Some compounds were evaluated for their anti-inflammatory activities against lipopolysaccharide (LPS)-induced TNF-α production in rat macrophage NR8383 cells. Sadigitaloide A showed noticeable anti-inflammatory activity at a concentration of 100.0 µM. At a concentration of 60 µM, sadigitaloide B exhibited better protection of dopaminergic neurons than the positive control n-butylidenephthalide in the Caenorhabditis elegans model injured by 6-OHDA. The phytotoxic activities of some compounds were attributed to considerable inhibitory effects on the growth of the roots and hypocotyls of Raphanus sativus L seedlings, especially cis, trans-abscisic acid, whose inhibition rates were much higher than those of glyphosate at concentrations ranging from 50 to 400 ppm. These results indicated that abietane-type diterpenoids possessed excellent anti-inflammatory and neuroprotective activities and further suggested that the low-molecular-weight compounds exhibited outstanding phytotoxic activities.

A case of skin ulcers secondary to extensive burns caused by flame and heavy metal-containing hydrothermal fluids / 中华烧伤杂志

On May 13, 2020, a 56-year-old man with extensive burns caused by flames and heavy metal-containing hydrothermal fluids was admitted to the General Hospital of Western Theater Command. After being admitted to the hospital, most of the burn wounds healed after treatments such as debridement, expansion, skin grafting, anti-shock, anti-infection, fluid replacement, and wound dressing change, etc. However, in the middle and late stages of treatment, the patient's burn wounds gradually showed repeated skin ulceration and inflammation. After excluding the cause of physical, bacterial infection and others, IgG4-related skin diseases was finally diagnosed by histopathological examination of tissue biopsy and concentration measurement of IgG4 in interstitial fluid, and the condition was improved after hormone treatment. This suggests that extensive burns may lead to the occurrence of autoimmune skin diseases. For the diagnosis of such diseases, it is necessary to combine clinical manifestations, serological examinations, and histopathological biopsy, etc. to avoid diagnostic pitfalls and draw correct conclusions.

Analysis of the Prognostic Value and Risk Factors of Early Relapse for Newly Diagnosed Multiple Myeloma Patients in the Era of Novel Agents / 中国实验血液学杂志

OBJECTIVE@#To investigate the influece of early relapse in the era of novel drugs on the prognosis of the patients with newly diagnosed multiple myeloma（NDMM） and risk factors, and to provide the basis for the early identification of the high-risk patients and guiding the treatment.@*METHODS@#The clinical data of the patients with NDMM admitted to our hospital from November 2011 to May 2022 were retrospectively analyzed. According to whether the progression free survival（PFS） was more than 12 months, they were divided into early relapse group（≤12 months） and late relapse group（＞12 months）. The high-risk factors of the patients in two groups were analyzed, including age, anemia, renal insufficiency, hypercalcemia, increasing of lactate dehydrogenase（LDH） level, Extramedullary disease (EMD), International Staging System（ISS） stage, Revised International Staging System （R-ISS） stage, cytogenetic abnormalities(CA) detected by fluorescence in situ hybridization（FISH）, and treatment efficacy. The meaningful clinical indicators were screened, and multivariate analysis was used to explore the high-risk factors of early relapse.@*RESULTS@#170 patients with NDMM were collected, including 25 cases in early relapse group and 145 cases in late relapse group. The median OS time of the patients in early death group was 20 months, and 140 months in late relapse group by the end of follow-up, there was significant difference in OS of the patients between two groups（P<0.001）. Fifteen patients（56.0％）in early relapse group obtained ≥VGPR, and 113（77.9%） patients in late relapse group, the difference was statistically significant（P=0.011）. Survival outcomes remained poor among early relapse patients irrespective of depth of response to initial therapy. Multivariate analysis showed that the EMD and high-risk CA predicted early relapse.@*CONCLUSION@#The prognosis of patients with early relapse in NDMM is poor. EMD and high-risk CA is an independent prognostic factor of early relapse.

Evaluation and improvement of blood station quality management system: based on external audit / 中国输血杂志

【Objective】 To identify the main unqualified items in the external audit of blood station quality management system (referred to as external audit), in order to take necessary measures to continuously improve the quality system. 【Methods】 Unqualified items(data) in the national and Shandong provincial blood safety technical audits (referred to as national and provincial audits) and four blood station blood safety technical joint audits (referred to as inter station mutual audits) from 2017 to 2019 were collected and analyzed by Excel and Pareto curves (graphs). Corresponding corrective and preventive measures were developed and implemented, and then tracked and evaluated by the quality management department three months after the external audit to verify their effectiveness. 【Results】 In a total of 7 external audits of blood station quality management system that our blood station has participated in over the past 3 years (including 2 national audits, 2 provincial audits, and 3 inter station mutual audits), the main unqualified terms were "12 monitoring and continuous improvement" 11.90% (15/126), "13 blood donation services" 11.90% (15/126), "06 equipment" 10.32% (13/126), "11 records" 10.32% (13/126), "03 organization and personnel" 8.73% (11/126), "15 blood preparation" 7.94% (10/126), "08 safety and health" 7.14% (9/126), and "14 blood testing" 7.14% (9/126). Among them, "monitoring and continuous improvement" ranked first in two national audits and two provincial audits, with 16.67% (5/30) and 14.71% (5/34), respectively, and was 8.06% (5/62) in inter station mutual audit, and the difference between the three kinds of audits was not statistically significant (P>0.05). "Records" accounted the highest proportion in inter station mutual review of 19.35% (12/62), while was respectively 0 and 2.94% (1/34) in national and provincial audits, with statistically significant difference between the three kinds of audits (P<0.05). 【Conclusion】 External audit against unqualified items is important for quality improvement. By analyzing the unqualified terms, taking corresponding measures to improve weak links, and evaluating the effectiveness of those measures, it can effectively ensure the effective operation of blood station quality management system.

Developing a diagnostic model for predicting prostate cancer: a retrospective study based on Chinese multicenter clinical data / 亚洲男科学杂志(英文版)

The overdiagnosis of prostate cancer (PCa) caused by nonspecific elevation serum prostate-specific antigen (PSA) and the overtreatment of indolent PCa have become a global problem that needs to be solved urgently. We aimed to construct a prediction model and provide a risk stratification system to reduce unnecessary biopsies. In this retrospective study, clinical data of 1807 patients from three Chinese hospitals were used. The final model was built using stepwise logistic regression analysis. The apparent performance of the model was assessed by receiver operating characteristic curves, calibration plots, and decision curve analysis. Finally, a risk stratification system of clinically significant prostate cancer (csPCa) was created, and diagnosis-free survival analyses were performed. Following multivariable screening and evaluation of the diagnostic performances, a final diagnostic model comprised of the PSA density and Prostate Imaging-Reporting and Data System (PI-RADS) score was established. Model validation in the development cohort and two external cohorts showed excellent discrimination and calibration. Finally, we created a risk stratification system using risk thresholds of 0.05 and 0.60 as the cut-off values. The follow-up results indicated that the diagnosis-free survival rate for csPCa at 12 months and 24 months postoperatively was 99.7% and 99.4%, respectively, for patients with a risk threshold below 0.05 after the initial negative prostate biopsy, which was significantly better than patients with higher risk. Our diagnostic model and risk stratification system can achieve a personalized risk calculation of csPCa. It provides a standardized tool for Chinese patients and physicians when considering the necessity of prostate biopsy.

A new diterpenoid from the leaves and twigs of Croton lachnocarpus Benth.

A new clerodane diterpenoid, crotolanin A (1), along with three known clerodane diterpenoids, crotoeurin B (2), teucvidin (3) and teucvin (4), was isolated from the ethanol extract of the leaves and twigs of Croton lachnocarpus Benth. Their structures were identified by extensive NMR spectroscopic and HRESIMS analyses. The dopaminergic neuroprotective activity of compounds 1-4 was tested by using transgenic Caenorhabditis elegans pathological model. Compound 2 alleviated dopaminergic neuron degeneration of worms induced by 6-hydroxydopamine (6-OHDA) that represented a potential therapy for Parkinson's disease (PD).

Cryptotanshinone Alleviates Oxidative Stress and Reduces the Level of Abnormally Aggregated Protein in Caenorhabditis elegans AD Models.

Alzheimer's disease (AD) is one of the leading causes of dementia. As the first common neurodegenerative disease, there are no effective drugs that can reverse the progression. The present study is to report the anti-AD effect of cryptotanshinone (CTS), a natural product isolated from Salvia castanea. It is found that it can alleviate AD-like features associated with Aß1-42 toxicity in muscle cells as well as neuronal cells of Caenorhabditis elegans (C. elegans). Further studies showed that CTS reduced the level of reactive oxygen species (ROS) in nematodes, up-regulated the expression of sod-3, and enhanced superoxide dismutase activity. Cryptotanshinone reduced the level of Aß monomers and highly toxic oligomers in C. elegans while inhibiting the abnormal aggregation of polyglutamine protein. In addition, CTS upregulated the expression of hsp-16.2 and downregulated the expression of ace-2. These results suggested that CTS could alleviate oxidative stress and reduce the level of abnormally aggregated proteins and has the potential to be developed as an anti-AD drug candidate.

Caesalpinbondin A, a Novel Diterpenoid Lactone With an Unprecedented Carbon Skeleton from the Seeds of Caesalpinia bonduc.

One novel diterpenoid lactone named caesalpinbondin A (1) that possesses an unprecedented tetracyclic ring system in which a 6/6/5-fused tricyclic ring and a 4,5-dimethyldihydrofuran-2(3H)-one were connected by a C-C single bond comprising a 5-(naphtho [2,3-b]furan-7-yl)dihydrofuran-2(3H)-one moiety was isolated from the seeds of Caesalpinia bonduc. Its chemical structure was established by extensive spectroscopic methods, and its absolute configuration was further determined by single-crystal X-ray diffraction analysis and electronic circular dichroism calculation. The biological evaluation suggested that compound 1 demonstrated potent anti-Alzheimer's disease (AD) bioactivity, which could delay paralysis of transgenic AD Caenorhabditis elegans. A possible biogenetic pathway of 1 was also proposed.

Diterpenoids with α-glucosidase inhibitory activities from the fruits of Vitex trifolia Linn.

Viticis Fructus, known as "Man-jing-zi", are the fruits of the traditional Chinese medicine Vitex trifolia Linn. and its variant Vitex trifolia Linn. var. simplicifolia. These fruits are used as folk medicines to treat various diseases. Although V. trifolia is useful for treating diabetes, the antidiabetic effect of its purified constituents is still under investigation. The phytochemical investigation on the ethanol extract of the fruits of V. trifolia yielded four new labdane diterpenoids vitetrolins A-D (1-4), together with seven (5-11) known analogs. The structures of these compounds were elucidated by spectroscopy techniques and the absolute configuration of 4 was determined by electronic circular dichroism (ECD) calculations. The isolated diterpenoids were evaluated for their α-glucosidase inhibitory activities. Compounds 5, 6, 8, and 9 exhibited moderate inhibitory activities against α-glucosidase with IC50 values ranging from 44.9 ± 6.1 to 70.5 ± 5.5 µM.

Diterpenoid Caesalmin C Delays Aß-Induced Paralysis Symptoms via the DAF-16 Pathway in Caenorhabditis elegans.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the world. However, there is no effective drug to cure it. Caesalmin C is a cassane-type diterpenoid abundant in Caesalpinia bonduc (Linn.) Roxb. In this study, we investigated the effect of caesalmin C on Aß-induced toxicity and possible mechanisms in the transgenic Caenorhabditis elegans AD model. Our results showed that caesalmin C significantly alleviated the Aß-induced paralysis phenotype in transgenic CL4176 strain C. elegans. Caesalmin C dramatically reduced the content of Aß monomers, oligomers, and deposited spots in AD C. elegans. In addition, mRNA levels of sod-3, gst-4, and rpt-3 were up-regulated, and mRNA levels of ace-1 were down-regulated in nematodes treated with caesalmin C. The results of the RNAi assay showed that the inhibitory effect of caesalmin C on the nematode paralysis phenotype required the DAF-16 signaling pathway, but not SKN-1 and HSF-1. Further evidence suggested that caesalmin C may also have the effect of inhibiting acetylcholinesterase (AchE) and upregulating proteasome activity. These findings suggest that caesalmin C delays the progression of AD in C. elegans via the DAF-16 signaling pathway and that it could be developed into a promising medication to treat AD.

Diterpenoids and C13 Nor-Isoprenoid Identified From the Leaves and Twigs of Croton yanhuii Activating Apoptosis and Pyroptosis.

Croton yanhuii (Family Euphorbiaceae) is an annual aromatic plant endemic to Yunnan Province, China, which yields an aromatic, spicy oil used as a flavoring and fragrance. The aim of the present study was to acquire secondary metabolites from the leaves and twigs of C. yanhuii and to evaluate their cytotoxic activity. Five new diterpenoids, croyanhuins A-E (1-5), and one new C13 nor-isoprenoid, croyanhuin F (6), were isolated from the leaves and twigs of C. yanhuii. Their structures and absolute configurations were determined by extensive spectroscopic methods (1D and 2D NMR, IR, and HRESIMS) and confirmed by electronic circular dichroism (ECD) spectra or single-crystal X-ray diffraction analysis. Among the new terpenoids, compounds 1 and 3 inhibited cell proliferation and viability in a dose- and time-dependent manner, whereas both induced cleavage of either caspase-3 or PARP-1 in the SW480 cell line. Additionally, we observed that Z-YVAD-FMK and Z-VAD-FMK, two caspase inhibitors, inhibited the compound-dependent cell viability loss, suggesting that either of them can induce pyroptosis and caspase-dependent apoptosis. These biological assay results revealed that compounds 1 and 3 induce different kinds of programmed cell death in SW480 cells.

A new highly oxygenated germacranolide from Carpesium nepalense var. lanatum (C.B.Clarke) Kitam.

A new highly oxygenated germacranolide, carcerlane A (1), together with four known highly oxygenated germacranolides (2-5), was isolated from an ethanol extract of the whole plant of Carpesium nepalense var. lanatum (C.B.Clarke) Kitam. The structures were determined by HRESIMS and extensive analysis of their spectroscopic data including IR, 1 D and 2 D NMR spectra. To our best knowledge, it was the first time to report the phytochemical investigation on this plant. The anti-Alzheimer's disease (AD) activities of 1-5 were evaluated using Caenorhabditis elegans AD pathological model. All the tested compounds showed that they have the anti-AD bioactivities of delaying worms paralysis.

Two new aromatic derivatives from Codonopsis pilosula and their α-glucosidase inhibitory activities.

The ethanol extract of the roots of Codonopsis pilosula was subjected to chromatographic fractionation, which result in the isolation and characterization of two new aromatic derivatives 2,3-dihydroxypropyl 2,4-dihydroxy-3,6-dimethylbenzoate (1) and 2-oxopropyl 3-hydroxy-4-methoxybenzoate (2), along with three known compounds pilosulinene A (3), pollenfuran B (4) and (+)-pinoresinol (5). Their structures were demonstrated by HRESIMS and spectroscopic methods including NMR and IR. It is worth noting that compound 4 was isolated for the first time from the genus Codonopsis. The potential hypoglycemic properties of compounds 2-5 were evaluated by measuring their α-glucosidase inhibitory effects. As a result, compounds 2 and 3 showed weak α-glucosidase inhibitory activities with IC50 values of 154.8 ± 11.0 µM and 24.0 ± 2.2 µM, respectively.[Formula: see text].

Buchwald-Hartwig Amination of Coordinating Heterocycles Enabled by Large-but-Flexible Pd-BIAN-NHC Catalysts.

A new class of large-but-flexible Pd-BIAN-NHC catalysts (BIAN=acenaphthoimidazolylidene, NHC=N-heterocyclic carbene) has been rationally designed to enable the challenging Buchwald-Hartwig amination of coordinating heterocycles. This robust class of BIAN-NHC catalysts permits cross-coupling under practical aerobic conditions of a variety of heterocycles with aryl, alkyl, and heteroarylamines, including historically challenging oxazoles and thiazoles as well as electron-deficient heterocycles containing multiple heteroatoms with BIAN-INon (N,N'-bis(2,6-di(4-heptyl)phenyl)-7H-acenaphtho[1,2-d]imidazol-8-ylidene) as the most effective ligand. Studies on the ligand structure and electronic properties of the carbene center are reported. The study should facilitate the discovery of even more active catalyst systems based on the unique BIAN-NHC scaffold.