Synthesis of 2-benzyl benzoxazoles and benzothiazoles via elemental sulfur promoted cyclization of styrenes with 2-nitrophenols and N,N-dialkyl-3-nitroanilines.

Herein we report a method for affording 2-benzyl benzoxazoles from substituted styrenes and 2-nitrophenols. The success of this method relies on the use of simple reagents, namely elemental sulfur and DABCO. A combination of identical reagents was utilized for the annulation of styrenes with N,N-dialkyl-3-nitroanilines to afford 2-benzyl benzothiazoles. Overall, benzoxazoles and benzothiazoles bearing useful functionalities such as halogens, amines, and heterocyclic groups were isolated in moderate to good yields. Our methods are a rare example of divergent transformations of substituted nitroarenes towards 2-benzyl benzoxazoles and benzothiazoles.

Metal-Free Annulation of 2-Nitrobenzyl Alcohols and Tetrahydroisoquinolines toward the Divergent Synthesis of Quinazolinones and Quinazolinethiones.

A simple metal-free method for the synthesis of quinazolinones from commercially available 2-nitrobenzyl alcohols and tetrahydroisoquinolines is developed. The reaction conditions were tolerant of an array of functionalities such as halogen, tertiary amine, protected alcohol, and ester groups. Under nearly identical conditions, quinazolinethiones were obtained in the presence of elemental sulfur and suitable mediators.

Copper-catalyzed synthesis of pyrido-fused quinazolinones from 2-aminoarylmethanols and isoquinolines or tetrahydroisoquinolines.

Pyrido-fused quinazolinones were synthesized via copper-catalyzed cascade C(sp2)-H amination and annulation of 2-aminoarylmethanols with isoquinolines or pyridines. The transformation proceeded readily in the presence of a commercially available CuCl2 catalyst with molecular oxygen as a green oxidant. Moreover, the dehydrogenative cross-coupling of 2-aminoarylmethanols with tetrahydroisoquinolines was explored, in which CuBr exhibited higher catalytic activity than CuCl2. Broad substrate scope with good tolerance of functionalities was observed under the optimized reaction conditions. The bioactive naturally occurring alkaloid rutaecarpine could be obtained by this strategy. The remarkable feature of this protocol is that complicated heterocyclic structures are readily achieved in a single synthetic step from easily accessible reactants and catalysts. This pathway to pyrido-fused quinazolinones would be complementary to existing protocols.

Sulfur-mediated annulation of 1,2-phenylenediamines towards benzofuro- and benzothieno-quinoxalines.

We report a method for condensation between ortho-phenylenediamines and ortho-hydroxyacetophenones to afford benzofuroquinoxalines. The reactions proceeded in the presence of an elemental sulfur mediator, DABCO base, and DMSO solvent. Functionalities such as nitrile, ester, and halogen groups were compatible. The conditions could be applicable for the synthesis of benzothienoquinoxalines from ortho-chloroacetophenones.

Functionalization of activated methylene C-H bonds with nitroarenes and sulfur for the synthesis of thioamides.

We report a method to obtain arylthioamides by the functionalization of sp3 C-H bonds in phenylacetic acids and benzyl alcohols. Reactions proceeded without the use of any solvents and were compatible with many functionalities and heterocycles. These conditions allow for a rapid synthesis of thioamides from simple, commercial substrates.

A new route to substituted furocoumarins via copper-catalyzed cyclization between 4-hydroxycoumarins and ketoximes.

A new route to substituted furocoumarins via copper-catalyzed cyclization between 4-hydroxycoumarins and ketoximes was developed. CuBr2 exhibited higher activity than other copper salts, affording the desired furocoumarins in high yields. The transformation proceeded readily in the absence of stoichiometric external oxidants. The significance of this synthetic strategy would be (1) the easily available starting materials; (2) low cost catalyst CuBr2; and (3) being without stoichiometric external oxidants. This protocol is complementary to previous approaches in the synthesis of substituted furocoumarins.

Oxidative annulation of acetophenones and 2-aminobenzothiazoles catalyzed by reusable nickel-doped LaMnO3 perovskites.

Synthesis of imidazole[2,1-b]benzothiazoles often suffers from the use of pre-functionalized substrates and/or homogeneous, non-recyclable catalytic systems. Herein we report a method for direct coupling of acetophenones and 2-aminobenzothiazoles in the presence of reusable perovskites, namely LaMn0.95Ni0.05O3. Imidazole[2,1-b]benzothiazoles were obtained in moderate to good yields and contained an array of useful functionalities. Control experiments indicated that the perovskites played pivotal roles in halogenation and condensation steps.

Retraction: New synthesis of 2-aroylbenzothiazoles via metal-free domino transformations of anilines, acetophenones, and elemental sulfur.

[This retracts the article DOI: 10.1039/D0RA01750G.].

The serum ferritin level is an important predictor of hemorrhagic transformation in acute ischaemic stroke.

BACKGROUND AND PURPOSE: Because hemorrhagic transformation (HT) is associated with morbidity and mortality, we need a better understanding of the factors that predict HT after ischaemic stroke. HT is a well-known factor that limits the use of thrombolytics and it negates the effect of treatment. This study investigated whether a high serum ferritin level is associated with HT in acute ischaemic stroke. METHODS: Seven hundred and fifty-two consecutive patients with acute ischaemic stroke within 24 h after a vascular event were enrolled. HT was diagnosed using magnetic resonance imaging (MRI) or computed tomography (CT) and the HT was classified into hemorrhagic infarction (HI) type 1, 2 and parenchymal hematoma (PH) type 1, 2. HT was also classified into no HT, asymptomatic HT, minor symptomatic HT (sHT), and major sHT. RESULTS: Computed tomography or MR showed HT in 90 patients (HI in 58 and PH in 32; asymptomatic in 53, minor symptomatic in 23 and major symptomatic in 14). The ferritin levels were higher in the patients who developed HT, PH and sHT. After adjustment for confounding variables, multivariate analysis showed that a high ferritin level remained an independent predictor of HT in the patients with acute ischaemic stroke (P < 0.001). Serum ferritin levels higher than 171.8 ng/ml were independently associated with sHT. CONCLUSIONS: This study suggests that a high ferritin level is an important predictor of HT, PH, and sHT in patients with acute ischaemic stroke. Lowering the ferritin level with iron-modifying agents or using free radical scavengers could be helpful to prevent HT in ischaemic stroke.

Self-Adaptive Dirhodium Complexes in a Metal-Organic Framework for Synthesis of N-H Aziridines.

Conformational dynamics of active sites in enzymes enable great control over the catalytic process. Herein, we constructed a metal-organic framework with conformationally dynamic active sites (Rh2-ZIF-8). The active sites in Rh2-ZIF-8 were composed of the imidazolate-bridged bimetallic center with a catalytic dirhodium moiety and structural zinc site. Even though the coordination sphere of the dirhodium species was saturated with two circularly arranged esp groups and two axial 2-MeIm ligands, it could still effectively catalyze the direct synthesis of N-H aziridines from olefins with high activity. We found that such a self-adaptive catalytic process was based on the dynamic breakage and reformation of the rhodium-zinc imidazolate bridges. Interestingly, the in situ generated dirhodium site with a unique Rh2(esp)2(2-MeIm)1 configuration was able to exhibit obviously enhanced selectivity compared to homogeneous catalyst Rh2(esp)2. Furthermore, the surrounding zinc imidazolate groups could effectively protect the dirhodium moieties from harsh environments, and this ultimately endowed it with high stability.

Copper-promoted direct sulfenylation of C1-H bonds in 4-aryl pyrrolo[1,2-a]quinoxalines.

Methods for direct functionalization of C(sp2)-H bonds in pyrrolo[1,2-a]quinoxalines have witnessed emerging development over the last decade. Herein we report a new tactic to afford a selective sulfenylation of 4-aryl pyrrolo[1,2-a]quinoxalines with diaryl disulfides. The reactions proceeded in the presence of a copper catalyst and potassium iodide promoter. Functionalities including nitro, ester, amide, methylthio, and halogen groups were all tolerated. Our method offers a convenient route to obtain highly substituted pyrrolo[1,2-a]quinoxalines-based thioethers in moderate to good yields.

Thrombolysis as a factor associated with favorable outcomes in patients with unclear-onset stroke.

BACKGROUND AND PURPOSE: Clinical and radiological features of patients with unclear-onset stroke do not differ significantly from those with known-onset stroke. There is a lack of evidence for the safety and efficacy of thrombolysis in patients with unclear-onset stroke. We sought to provide supportive data on the safety and efficiency of thrombolysis in patients with unclear-onset stroke. METHODS: We retrospectively identified patients with unclear-onset stroke (<3 h of first found abnormal time) from our stroke registry. We performed following protocols for thrombolysis in patients with unclear-onset stroke; initial conventional CT-based intravenous thrombolysis (IVT), repeat MRI during IVT, and then decision to maintain IVT or to perform combined intra-arterial thrombolysis. In addition, we compared clinical outcomes and safety between thrombolyzed and non-thrombolyzed patients. RESULTS: A total of 78 patients with unclear-onset stroke were included. Twenty-nine patients underwent thrombolysis. Thrombolysis (OR, 6.842; 95% CI, 1.950-24.004; P = 0.003) and baseline NIHSS (OR, 0.769; 95% CI, 0.645-0.917; P = 0.003) were associated with favorable outcomes at 3 months in multivariate logistic regression analysis. The frequency of hemorrhagic transformation and symptomatic ICH was not significantly different between the thrombolyzed and non-thrombolyzed patients (34.4% vs. 40.7% and 10.3% vs. 8.2%, respectively). CONCLUSION: The results of this study suggest that thrombolysis in unclear-onset stroke could be independently associated with favorable outcomes at 3 months and that thrombolysis based on repeat imaging appears to be safely applied to patients with unclear-onset stroke.

Clinical implications of collateral middle cerebral artery flow in acute ischaemic stroke with internal carotid artery occlusion.

BACKGROUND AND PURPOSE: The presence of collateral middle cerebral artery (MCA) flow via the primary collateral pathway is thought to protect against the progression of cerebral ischaemia. However, there have been few reports on early clinical outcomes according to the presence of collateral MCA flow in acute ischaemic stroke (AIS) with internal carotid artery (ICA) occlusion. Therefore, we sought to investigate the early clinical outcomes and lesion patterns according to the presence of collateral MCA flows in AIS with ICA occlusion. METHODS: This is a retrospective study of patients with AIS with ICA occlusion consecutively admitted to our stroke center between October 2008 and March 2010. Patients were included if they were admitted within 12 h of symptom onset with AIS and symptomatic ICA occlusion. Collateral MCA flow was defined as the presence of MCA signals from proximal M1 to distal MCA branches ipsilateral to the ICA occlusion by magnetic resonance angiography. Early neurological deterioration (END) was defined as a 4-point increase in the National Institutes of Health Stroke Scale (NIHSS) score and persistent neurological deterioration for at least 24 h or newly developed neurological symptoms within 7 days. RESULTS: Sixty-five patients (42 men, 23 women) were finally included. Initial NIHSS scores were significantly lower, and favorable outcomes at 3 months were better in patients with collateral MCA flow than in those without (P < 0.001). Initial lesion patterns were different according to the collateral MCA flow. However, patients with mild AIS might more frequently deteriorate than those with moderate to severe AIS. CONCLUSIONS: In our study, collateral MCA flow reduced initial stroke severity and was associated with favorable outcomes at 3 months but did not seem to protect against END in mild AIS patients with ICA occlusion. Therefore, the results of this study suggest that mild AIS patients with ICA occlusion should be carefully managed because their conditions may deteriorate.

Efficient Removal of Chromium(VI) Anionic Species and Dye Anions from Water Using MOF-808 Materials Synthesized with the Assistance of Formic Acid.

This study presents a simple approach to prepare MOF-808, an ultra-stable Zr-MOF constructed from 6-connected zirconium clusters and 1,3,5-benzene tricarboxylic acid, with tailored particle sizes. Varying the amount of formic acid as a modulator in the range of 200-500 equivalents results in MOF-808 materials with a crystal size from 40 nm to approximately 1000 nm. Apart from the high specific surface area, a combination of a fraction of mesopore and plenty of acidic centers on the Zr-clusters induces a better interaction with the ionic pollutants such as K2Cr2O7 and anionic dyes. MOF-808 shows uptakes of up to 141.2, 642.0, and 731.0 mg/g for K2Cr2O7, sunset yellow, and quinoline yellow, respectively, in aqueous solutions at ambient conditions. The uptakes for the ionic dyes are significantly higher than those of other MOFs reported from the literature. Moreover, the adsorption capacity of MOF-808 remains stable after four cycles. Our results demonstrate that MOF-808 is a promising ideal platform for removing oxometallates and anionic dyes from water.

Cobalt-catalyzed annulation of styrenes with α-bromoacetic acids.

We report a method for addition of α-bromophenylacetic acids to vinyl C[double bond, length as m-dash]C bonds in styrenes to afford γ-lactones. Reactions employed a simple cobalt catalyst Co(NO3)2·6H2O in the presence of dipivaloylmethane (dpm) ligand. Many functionalities including halogen, ester, and nitro groups were compatible with reaction conditions. If α-bromoesters were used, vinylacetates were the major products.

Cobalt-catalyzed, directed arylation of C-H bonds in N-aryl pyrazoles.

We report a method for directed ortho-arylation of N-aryl pyrazoles with arylboronic acids. Reactions proceeded in the presence of a Co(hfacac)2 catalyst, CeSO4 oxidant, and HFIP solvent. Functionalities such as nitro, ester, bromo, and ketone groups were compatible with the reaction conditions. Using heterocycles including thiophene and carbazole was also feasible.

Correction: Cobalt-catalyzed, directed arylation of C-H bonds in N-aryl pyrazoles.

[This corrects the article DOI: 10.1039/D1RA00975C.].

Usefulness of direct sequencing of pooled DNA for SNP identification and allele-frequency determination compatible with a common disease/common variant hypothesis.

We examined the efficiency of direct sequencing of pooled DNA for developing common single nucleotide polymorphisms (SNPs) and its accuracy for estimating allele frequencies. A pool of 200 control DNAs was established and was used for developing SNPs and estimating minor allele frequencies (MAF). The sensitivity of the pooled DNA method for successfully detecting an SNP with an MAF >0.01 listed in the database was approximately 0.7; it was particularly efficient for detecting SNPs with MAF >0.1, which is compatible with the common disease/common variant hypothesis. The mean difference between the estimated and the observed MAFs was 0.03 +/- 0.023. The pooled DNA method identified four additional SNPs, for which the allele frequency information was not available in the database. The pooled DNA method is a cost- and time-effective tool for both qualifying and quantifying SNPs with considerable accuracy, and it can be particularly useful for dissecting the common disease/common variant hypothesis; this represents a best-case scenario for large-scale association mapping.

Functionalization of C-H bonds in acetophenone oximes with arylacetic acids and elemental sulfur.

Fused thieno[3,2-d]thiazoles were synthesized via a coupling of acetophenone ketoximes, arylacetic acids, and elemental sulfur in the presence of Li2CO3 base. Functionalities including chloro, bromo, fluoro, trifluoromethyl, and pyridyl groups were compatible with reaction conditions. High yields and excellent regioselectivities were obtained even if meta-substituted ketoxime acetates were used. Ethyl esters of heteroarylacetic acids were competent substrates, which is very rare in the literature. Our method would offer a convenient protocol to afford polyheterocyclic structures from simple substrates.

Hydrogen peroxide-mediated synthesis of 2,4-substituted quinazolines via one-pot three-component reactions under metal-free conditions.

An efficient metal-free synthesis of 2,4-substituted quinazolines via a hydrogen peroxide-mediated one-pot three-component reaction of 2-aminoaryl ketones, aldehydes, and ammonium acetate has been developed. The transformation proceeded readily under mild conditions in the presence of commercially available hydrogen peroxide. The significant advantages of this approach are (1) the readily available atom-efficient and green hydrogen peroxide as oxidant; (2) no transition metal catalyst is required; (3) mild reaction conditions; and (4) wide substrate scope. To the best of our knowledge, utilizing hydrogen peroxide as an atom-efficient and green oxidant for the synthesis of 2,4-substituted quinazolines has not previously been reported in the literature. This method is complementary to previous protocols for the synthesis of 2,4-substituted quinazolines.