This paper describes an iridium-catalyzed allylation of ring-fused pyrazolones that proceeds with excellent regio-, diastereo- and enantio-selectivities. The approach exploits unactivated, racemic allylic alcohols as a source of allyl building blocks. Asymmetric syntheses of a series of biologically relevant, chiral pyrazolones highlight the utility of the methodology.
View Article and Find Full Text PDFPurpose: The primary objective of this study is to evaluate and compare the clinical and radiographic outcomes of the combined spinous process-splitting approach with a Wiltse (SPSW) approach, the combined conventional approach with a Wiltse (CW) approach, and the conventional open (CO) approach in unilateral transforaminal lumbar interbody fusion (TLIF).
Methods: The clinical outcomes were assessed, and intraoperative data and complications were collected. Numeric Rating Scale (NRS) scores for low back pain and leg pain, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) scores for evaluating functions of the lumbar spine and health-related quality of life, and the modified MacNab standard for assessing satisfaction were analyzed.
A family of polystyrene-supported (phosphoramidite, olefin) ligands -, based on the original design by Defieber and Carreira, has been developed and applied in iridium-catalyzed asymmetric allylic amination of unmasked allylic alcohols (27 examples, up to 99% ee). Among them, functional resins and exhibit important advantages such as easy preparation, ligand recyclability, and easy handling for sequential use. As a distinctive advantage, the catalytic use of the iridium complexes of and allows the straightforward reuse of a high percentage of the expensive iridium metal involved in the complexes, which is not achievable under homogeneous conditions with the corresponding monomeric complexes.
View Article and Find Full Text PDFMerging polymer-supported asymmetric organocatalysis with continuous flow in a packed bed reactor has been used as the key, enantiodetermining step in a short synthesis of indoloquinolizidines. Using this approach, a highly enantioselective, solvent-free and rapid conjugate addition of dimethyl malonate to a diverse family of cinnamaldehydes in continuous flow, allowing the preparation of relevant oxodiesters in multigram amounts has been developed. The obtained Michael adducts have been used to complete an expedient diastereoselective synthesis of indoloquinolizidine cascade Pictet-Splengler cyclisation-lactamisation in continuous flow.
View Article and Find Full Text PDFObjective: To explore the safety and feasibility of posterior pars interarticularis screw fixation on axis by CT measurement.
Methods: The CT data of 137 patients with complete upper cervical spine who underwent full cervical spine CT examination from January 2016 to December 2019 were collected, including 71 males and 66 females, aged from 22 to 65 years old with an average of (41.8±17.
Under catalysis by chiral phosphine, an asymmetric isomerization/annulation cascade reaction of allylamines with allenoates was realized. A wide range of γ-substituted allenoates were tolerated to afford chiral pyrroline derivatives in high yields with excellent enantioselectivities. In the reaction, isomerization of readily available -allylamines to reactive aliphatic imines through a 1,4-proton shift is a key step, which circumvents the isolation of highly unstable alkyl -sulfonylimines.
View Article and Find Full Text PDFThe δ-sulfonamido-substituted enones were employed as phosphine acceptor in phosphine-catalyzed (4 + 2) annulation of 1,1-dicyanoalkenes. They served as a four-membered synthon to react with 1,1-dicyanoalkenes under mild reaction conditions, producing piperidine derivatives in moderate to excellent yields with good to excellent diastereoselectivities.
View Article and Find Full Text PDFObjective: To compare the clinical effecty of Wiltse approach combined with contralateral transforaminal lumbar interbody fusion (TLIF) and traditional TLIF in the treatment of lumbar disc herniation and its affect on injury of multifidus muscle.
Methods: From June 2014 to September 2017, 90 patients with lumbar disc herniation combined with lumbar spine instability were divided into two groups (Wiltse approach group and traditional group) depend on the procedure of operation. Wiltse approach group was treated with Wiltse approach screw placement in one side combined with contralateral TLIF.
Astragaloside IV (AS#IV) has previously demonstrated antitumoractivity. We investigated the effect and mechanisms of AS#IV in relation to epithelial-mesenchymal transition (EMT), viainterference with the Wnt/β-catenin signaling pathway in gliomaU251 cells. Induction of glioma U251 cells by transforming growthfactor (TGF)#β1 activated EMT, including switching E#cadherin toN-cadherin and altering the expression of Wnt/β-catenin signalingpathway components such as vimentin, β-catenin, and cyclin-D1.
View Article and Find Full Text PDFIn this manuscript, phosphine-dependent [3 + 3] and [4 + 3] annulation reactions of allenoate with aziridines were disclosed. The alkyldiphenylphosphine-promoted [4 + 3] annulation of allenoate with aziridines has been achieved under mild conditions, providing biologically interesting functionalized tetrahydroazepines in moderate to excellent yield with moderate to excellent regioselectivity and diastereoselectivity.
View Article and Find Full Text PDFAlthough carbon-carbon, carbon-nitrogen, and carbon-oxygen double bonds or their combinations have extensively been applied in phosphine-catalyzed asymmetric cycloaddition, a nitrogen-nitrogen double bond has never been investigated in chiral phosphine catalysis. In this paper, we present phosphine-catalyzed asymmetric [3+2] cycloaddition of diazenes with Morita-Baylis-Hillman (MBH) carbonates to give chiral dihydropyrazoles in high yields with excellent enantioselectivities. Various MBH carbonates and diazenes worked well under the mild reaction conditions.
View Article and Find Full Text PDFIn this communication, a chiral squaramide-catalyzed asymmetric dearomative tandem annulation reaction of unmodified Morita-Baylis-Hillman alcohols with azomethine imines has been achieved through a kinetic resolution of MBH alcohols under mild conditions, giving pharmaceutically interesting functionalized hetero-bicyclo[3.3.1]nonane derivatives in good to excellent yields with excellent enantioselectivities.
View Article and Find Full Text PDFThe phosphine-catalyzed tandem annulation reaction of Morita-Baylis-Hillman (MBH) alcohols with azomethine imines has been achieved for the synthesis of biologically important (epoxymethano)-pyrazolo[5,1- b]quinazoline derivatives. A variety of MBH alcohols and azomethine imines were well-tolerated under the mild reaction conditions, providing novel 3D heterocyclic compounds in high yields with excellent diastereoselectivities. It is the first time the direct activation of unmodified MBH alcohols acting as new oxa-synthons has been achieved.
View Article and Find Full Text PDFPhosphine-catalyzed [3+2] annulation of β-sulfonamido-substituted enones and sulfamate-derived cyclic imines has been developed, giving a series of imidazoline derivatives in moderate to excellent yields with good to excellent diastereoselectivities. A scale-up reaction worked well under mild reaction conditions. A possible mechanism was proposed on the basis of the results obtained.
View Article and Find Full Text PDFObjective: To analyze the clinical efficacy of unilateral and bilateral intervertebral space release in the treatment of lower lumbar spondylolisthesis.
Methods: The clinical data of 41 patients with lumbar spondylolisthesis treated by surgery from October 2012 and May 2016 were retrospcetive analyzed. The patients were divided into two groups, 18 cases were enrolled in unilateral intervertebral release group, there were 7 males and 11 females, aged from 47 to 75 years old with an average of (59.
A diastereoselective construction of biologically important tetrahydrocyclopenta[ b]naphthalene derivatives has been achieved via a phosphine-catalyzed [3 + 2] annulation of 2-hydroxy-1,4-naphthaquinone derivatives and allenoate. Various tetrahydrocyclopenta[ b]naphthalene derivatives containing contiguous quaternary carbon centers are obtained in good yields with excellent diastereoselectivities. The asymmetric version gave the chiral product in up to 57% ee under catalysis of Kwon chiral phosphine.
View Article and Find Full Text PDFBMC Musculoskelet Disord
August 2018
Background: The use of bone graft for the radial head fractures has been previously described and occasionally used by other authors.This is the first paper, to my knowledge, dealing with the relevant issue about the importance that the use of an autologous bone graft can have on the radial head fractures.
Methods: From July 2010 to July 2014, 20 consecutive patients who underwent open reduction and internal fixation for a closed Mason type II radial head fracture were retrospectively reviewed.
In this paper, a phosphine-catalyzed [8 + 2]-annulation of heptafulvene with allenoates has been achieved under mild conditions, giving functionalized bicyclo[5.3.0]decane derivatives in moderate to excellent yields.
View Article and Find Full Text PDFA palladium-catalyzed enantioselective [4 + 2] cycloaddition reaction of vinyl benzoxazinones with sulfamate-derived cyclic imines is described, affording the tetrahydroquinazolines bearing several functional rings in high yields (up to 99% yield) with good to excellent diastereoselectivities and excellent enantioselectivities (up to 96% ee). This reaction represents the first Pd-catalyzed asymmetric decarboxylative cycloaddition of vinyl benzoxazinones with imines.
View Article and Find Full Text PDFPhosphine-catalyzed [5+1] annulation of δ-sulfonamido-substituted enones with -sulfonylimines for the synthesis of 1,2,3,6-tetrahydropyridines is developed. The reaction proceeds smoothly under mild reaction conditions to give the annulation products in moderate to excellent yields. Mechanistic exploration of this new annulation shows that the δ-sulfonamido-substituted enone and the -sulfonylimine serve as C5 and C1 synthons to furnish the annulation, respectively.
View Article and Find Full Text PDFA multifunctional chiral phosphine-catalyzed enantioselective [3+2] annulation of Morita-Baylis-Hillman carbonates with cyclopentenones provides a direct approach to access functional 4-oxo-1,3a,4,5,6,6a-hexahydropentalene compounds. Moderate to good yields and excellent enantioselectivities (>90% ee) were obtained for a series of substrates under mild reaction conditions.
View Article and Find Full Text PDFPalladium-catalyzed [5 + 2] cycloaddition of 2-aryl-2-vinyloxiranes with sulfamate-derived cyclic imines is described. The zwitterionic allylpalladium intermediates act as five-membered synthon to react with sulfamate-derived cyclic imines to furnish [5 + 2] cycloaddition, giving 1,3-oxazepine derivatives in moderate to excellent yields with excellent regioselectivities.
View Article and Find Full Text PDFA bifunctional phosphine-catalyzed highly enantioselective [2+4] cycloaddition of α-substituted allenoates with (E)-1-benzyl-4-olefinicpyrrolidine-2,3-diones has been achieved, giving pyrrolidin-2-one fused dihydropyran derivatives in moderate to good yields with excellent enantioselectivities (up to 98% ee). This reaction provides a useful catalytic asymmetric access to dihydropyran structural motifs.
View Article and Find Full Text PDFWith the use of a commercially available chiral phosphine as the catalyst, the first catalytic enantioselective [4 + 3] annulation of allenoates with C,N-cyclic azomethine imines is developed. The reaction works efficiently under mild reaction conditions to afford seven-membered ring-fused quinazoline-based tricyclic heterocycles in high yields with good to excellent diastereo- and enantioselectivities.
View Article and Find Full Text PDFPhosphine-catalyzed [2 + 4] annulation of allenoates with thiazolone-derived alkenes has been achieved under mild conditions, giving biologically important 6,7-dihydro-5H-pyrano[2,3-d]thiazole derivatives in high to excellent yields. With the use of Kwon's phosphine as the chiral catalyst, optically active products were obtained in good yields with excellent enantioselectivities.
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