Ruthenium-catalyzed asymmetric hydrogenation of aromatic and heteroaromatic ketones using cinchona alkaloid-derived NNP ligands

A series of cinchona alkaloid-based NNP ligands, including a new one, have been employed for the asymmetric hydrogenation of ketones. By combining ruthenium complexes, various aromatic and heteroaromatic ketones were smoothly reacted, yielding valuable chiral alcohols with extremely high 99.9% ee. Moreover, a proposed reaction mechanism was discussed and verified by NMR.

A series of cinchona alkaloid-based NNP ligands including a new one has been employed for the asymmetric hydrogenation of ketones. By combining ruthenium complexes, various ketones were smoothly reacted with up to 99.9% ee.

Since the well-known failure of using racemic thalidomide, attention has been paid to the manufacture of optically pure compounds as effective components in pharmaceuticals and agrochemicals. Asymmetric hydrogenation of ketones, especially heteroaromatic ketones, has emerged as a popular facile route to approach enantiopure secondary alcohols as essential intermediates for the construction of biologically active molecules.^1–4 Knowles et al.⁵ pioneered the production of enantioenriched chiral compounds in 1968, and Noyori and co-workers^6–8 laid the cornerstone of asymmetric hydrogenation in 1990s. Subsequently, numerous catalytic systems have been developed. Ru-BICP-chiral diamine-KOH was developed and proved to be effective for asymmetric hydrogenation of aromatic ketones by Xumu Zhang.⁹ Cheng-yi Chen reported asymmetric hydrogenation of ketone using trans-RuCl₂[(R)-xylbinap][(R)-daipen] and afforded secondary alcohol in 92–99% ee.¹⁰ Mark J. Burk and Antonio Zanotti-Gerosa disclosed Phanephos-ruthenium-diamine complexes catalyzing the asymmetric hydrogenation of aromatic and heteroaromatic ketones with high activity and excellent enantioselectivity.¹¹ Qi-Lin Zhou et al. designed and synthesized chiral spiro diphosphines as a new chiral scaffold applied in the asymmetric hydrogenation of simple ketones with extremely high activity and up to 99.5% ee.^12–15 Similarly, Kitamura and co-workers have developed a set of tridentate binan-Py-PPh₂ ligands for the asymmetric hydrogenation of ketones affording excellent results.¹⁶ Recently, chiral diphosphines and tridentate ligands based on ferrocene have been developed for the asymmetric hydrogenation of carbonyl compound with a remarkable degree of success.^17–21 Despite many ligands for asymmetric hydrogenation of ketones have been reported, expensive reagent and multistep complicated reactions were employed to synthesize most of them.^22–24 In light of increasing industrial demand, easily obtained, cheap and practical chiral ligands are still highly desirable. In addition to chiral ligands, the selection of metals was essential for asymmetric hydrogenation.^25–27 Although Mn,^28–30 Fe,^31–34 Co,^35–37 Ni^38,39 and Cu^40,41 metals were proved to be effective for asymmetric hydrogenation in recent years, Rh,^42–44 Ir^45,46 and especially Ru remained the most preferred metals. Ruthenium^47–51 was chosen owing to its superior performances in terms of low price, selectivity and activity. Takeshi Ohkuma,⁵² Hanmin Huang^53,54 and Johannes G. de Vries⁵⁵ all successfully used ruthenium catalysts for asymmetric hydrogenation of ketones. Admittedly, there is a continuing interest in the development of cheaper, simpler and more efficient catalysts for the asymmetric hydrogenation of ketones under mild conditions to access corresponding secondary alcohols. Recently, we developed new NNP chiral ligands derived from cinchona alkaloid for the asymmetric hydrogenation of various ketones in extremely excellent results using a iridium catalytic system.⁵⁶ Prompted by these encouraging results, we were interested in exploring a ruthenium-catalyzed asymmetric hydrogenation of ketones with NNP chiral ligands derived from cinchona alkaloid. Here, we showed that changing from iridium to ruthenium, with the same simple synthetic ligands, delivered a catalyst catalyzed asymmetric hydrogenation of ketones to give the industrially important chiral alcohols with up to 99.9% ee. Although the catalytic activity of ruthenium catalyst was not as high as that of the iridium catalyst, the enantioselectivity could be maintained, and even showed higher enantioselectivity in the hydrogenation of some substrates.Chiral tridentate ligand NNP (L1–L10) were synthesized and characterized as reported in our previous publication. With tridentate ligands in hand, we began to evaluate the catalytic performance in benzylidene-bis(tricyclohexylphosphine) dichlororuthenium-catalyzed asymmetric hydrogenation of acetophenone employed as a standard substrate (Fig. 2). MeOH was found to be a better one as the conversion and enantioselectivity were 99.9% and 98.2%, respectively. Bases screening showed that Ba(OH)₂ was superior to the others, giving >99.9% conversion and 98.8% ee in the present catalytic system (Fig. 1). Ligand screening revealed that the configuration of chiral centers of cinchona alkaloids of the ligand markedly affected the catalytic performance. NNP ligands derived from cinchonine and quinidine appeared to benefit both the reaction rate and enantioselectivity, while those derived from cinchonidine and quinine had the opposite effect. Further, different NNP ligands that bearing different substituents on the phenyl rings were evaluated. Similar to our previous research, ligands with electron-withdonating substituents showed better catalytic performance than those with electron-withdrawing substituents. However, it was noted that the more electron-withdonating substituents furnished lower activity but same enantioselectivity. The optimal ligand L5 derived from quinidine with one methoxy group on benzene ring provided the corresponding chiral alcohol with 99.9% conversion and 98.8% ee. Considering that L3 derived from cinchonine had similar catalytic performance to L4 derived from quinidine, new ligand L10 similar to L5 with one methoxy group on benzene ring was synthesized and applied to the asymmetric hydrogenation of template substrate. 99.6% conversion and 97.6% ee was obtained. Hence, L5 was employed as better ligand in subsequent experiments.Open in a separate windowFig. 1The effect of different bases for the asymmetric hydrogenation of acetophenone (substrate/Ru/L5 = 500/1/2, ketones: 0.429 mol L⁻¹, base: 0.15 mol L⁻¹, MeOH: 2 mL, 30 °C, 6 MPa, 2 h.).Open in a separate windowFig. 2The effect of different solvents for the asymmetric hydrogenation of acetophenone. (substrate/Ru/L5 = 1000/1/2, ketones: 0.858 mol L⁻¹, Ba(OH)₂: 0.15 mol L⁻¹, solvent: 2 mL, 30 °C, 6 MPa, 2 h.).The effect of different ligand for the asymmetric hydrogenation of acetophenone^a

腹腔镜胆囊切除胆道损伤20例诊治体会

近年来随着腹腔镜胆囊切除术(LC)的广泛开展,胆道损伤呈上升趋势,其发生率为0.4%～1.3%[1].如何避免胆道损伤,成功地进行胆道修复,最大限度地减轻患者的痛苦,是临床医师所面临的重要课题.我们总结了20例腹腔镜胆道损伤的临床资料,报告如下.     

sLex expression in invasive micropapillary breast carcinoma is associated with poor prognosis and can be combined with MUC1/EMA as a supplementary diagnostic indicator

Objective:Mucin 1 (MUC1/EMA) and sialyl Lewis X (sLe^x) indicate polarity reversal in invasive micropapillary carcinoma (IMPC). The purpose of this study was to evaluate the expression of MUC1/EMA and sLe^x and to assess their diagnostic and prognostic value in patients with IMPC.Methods:The expression of sLe^x and MUC1/EMA in 100 patients with IMPC and a control group of 89 patients with invasive ductal carcinoma not otherwise specified (IDC-NOS) were analyzed with IHC. Fresh tumor tissues were collected from patients with IMPC or IDC-NOS for primary culture and immunofluorescence analysis.Results:The rate of nodal metastasis was higher in patients with IMPC than those with IDC-NOS, and IMPC cells tended to express more sLe^x and MUC1/EMA in the cytomembranes (the stroma-facing surfaces of the micropapillary clusters) than IDC-NOS cells. In IMPC, high cytomembrane expression of sLe^x, but not MUC1/EMA, indicated poor prognosis. In addition, among the 100 patients with IMPC, 10 patients had sLe^x+/EMA– expression patterns, and 8 patients had sLe^x–/EMA+ expression patterns. The primary IMPC cells were suspended, non-adherent tumor cell clusters, whereas the primary IDC cells were adherent tumor cells. Immunofluorescence analysis showed that MUC1/EMA and sLe^x were co-expressed on the cytomembranes in IMPC cell clusters and in the cytoplasm in IDC-NOS cells.Conclusions:sLe^x can be used as a prognostic indicator and can be combined with MUC1/EMA as a complementary diagnostic indicator to avoid missed IMPC diagnosis.     

Deer antler based active ingredients have protective effects on LPS/d-GalN-induced acute liver injury in mice through MAPK and NF-κB signalling pathways

ContextDeer antler based active ingredients are known to have certain anti-inflammatory and antioxidant activities. However, its potential hepatoprotective effect remains unclear.ObjectiveThis article reports the hepatoprotective effect of protein components in deer antler bases (R1) on lipopolysaccharide/d-galactosamine (LPS/d-GalN)-induced acute liver injury (ALI) in mice, and explores its possible mechanism.Materials and methodsThe four separated and purified protein components of deer antler bases were screened and verified by the RAW264.7 cell inflammation model. In the in vivo experiment of LPS/d-GalN-induced ALI in mice, ALT, AST, SOD, CAT, GSH and MDA were detected. The liver histopathology was analysed, the COX-2 and iNOS proteins were analysed by immunohistochemistry, and 4-HNE was analysed by immunofluorescence staining. In addition, the effects on the MAPK pathway and NF-κB/IκB-α pathway in liver proteins were explored.ResultsWith isolated RA protein fraction pre-treated RAW264.7 cells, NO production decreased by 35.3% compared with the model group. The experimental results of ALI in mice induced by LPS/d-GalN show that R1 protein components can protect mice from ALI through anti-inflammatory and anti-oxidative stress effects and reduce liver pathological damage in mice. The results also indicate that the R1 protein component may protect the liver by inhibiting the activation of the MAPK pathway and the NF-κB/IκB-α pathway induced by LPS/d-GalN.ConclusionsThe separated and purified R1 protein component of deer antler base has a good protective effect on LPS/d-GalN-induced liver injury, and may become a potential material for protecting against liver injury.     

肝脏血管周上皮样细胞肿瘤的临床及影像学特征

回顾性分析4例经病理证实的肝脏血管周上皮样细胞肿瘤(PEComa)患者影像资料,总结其影像特点并复习相关文献。4例患者均为体检发现,无乙肝病史。3例患者病变密度/信号均匀,1例病变密度/信号混杂,内见脂肪密度/信号。4例患者病变动脉期明显强化,2例包膜样延迟强化,3例强化特点呈快进快出。肝脏PEComa动脉期均为明显强...     

关节镜辅助下自体肌腱重建内侧髌股韧带治疗复发性髌骨脱位的疗效

目的：探讨胫骨结节内移垫高截骨联合内侧髌股韧带重建和关节镜下外侧支持带松解治疗复发性髌骨脱位的疗效。方法：对28例复发性髌骨脱位患者（男3例,女25例）,行胫骨结节内移垫高截骨联合内侧髌股韧带重建和关节镜下外侧支持带松解治疗,术中先在镜下检查髌骨轨迹,手术前后髌骨CT扫描测量髌股合适角、髌骨倾斜角及髌骨外移率以及Kujala、Lysholm和Tegner运动功能评分评估膝关节功能。结果：所有患者均获得随访,随访时间12~33月,平均18.5个月,最后随访时膝关节症状得到改善,CT检查髌骨适合角、髌骨倾斜角及髌骨外移率分别由术前的（33.85±4.30）°、（12.23±1.78）°、（47.7±2.61）%降低到（11.58±1.86）°、（8.35±1.52）°、（8.80±1.63）%,均有统计学差异（P=0.000）;Kujala、Lysholm和Tegner运动功能评分分别由术前的（57.70±2.93）、（56.3±2.53）、（3.40±0.94）分提高到（89.90±2.87）、（91.40±2.06）、（5.2０±1.07）分,均有统计学差异（P=0.000）。结论：胫骨结节内移垫高截骨联合内侧髌股韧带重建和关节镜下外侧支持带松解能有效治疗复发性髌骨脱位,改善膝关节的稳定性并避免脱位复发,利于患者膝关节功能恢复。     

应用siRNA敲低TPM3基因表达后对大鼠胰腺癌细胞侵袭转移能力的影响

目的：探究原肌球蛋白3（tropomyosin alpha-3 chain,TPM3）在大鼠胰腺癌细胞中对其侵袭转移能力的影响并初步阐述其可能的分子机制。方法：（1）将70只大鼠随机分为手术组40只[将7,12-二甲基苯并蒽（7,12-dimethyl-1,2-benzanthracene,DMBA]植入大鼠胰腺被膜下后荷包缝合被膜）,假手术组15只（只对胰腺进行荷包缝合而后关腹,不置入DMBA）,阴性对照组15只（不做任何处理）,建立大鼠胰腺癌模型。（2）通过组织免疫组化染色的方法对差异蛋白TPM3进行验证。（3）通过机械分离和酶阶段消化法分离胰腺癌组织的方法获取大鼠胰腺癌细胞,体外传代培养获得纯度较高的细胞后,应用siRNA敲低大鼠胰腺癌细胞中TPM3基因的表达;通过RT-PCR技术检测其沉默效果。（4）通过Transwell实验和平板克隆实验分别对细胞的侵袭、迁移能力及生长增殖能力进行观察。结果：（1）经病理验证模型组有37.83%（14/37）形成胰腺癌,证明大鼠胰腺癌模型建立成功。（2）免疫组化验证胰腺癌组织中TPM3阳性率（92.8%）明显高于正常胰腺组织（6.7%）。（3）RT-PCR结果显示,转染TPM3-siRNA的细胞中TPM3的表达量（0.31±0.02）明显低于其余各组,脂质体组（0.45±0.02）,阴性对照组（0.45±0.02）,空白对照组（0.43±0.02）（P＜0.05）,其余各组之间TPM3表达量差异无统计学意义（P ＞0.05）。（4）转染TPM3-siRNA的细胞其侵袭[（161.63±4.94）个]、迁移能力[（206.87±4.21）个]及生长增殖能力[（51.5±2.327）个]较对照组明显降低[分别为（39.7±1.40）个,（67.27±1.76）个,（5.900±0.767）个]（P＜0.05）。结论：体外化学合成的TPM3-siRNA可有效的抑制大鼠胰腺细胞TPM3的表达,TPM3表达降低后其侵袭能力、迁移能力及生长增殖能力下降。     

人肝再生增强因子真核表达及其对顺铂诱导肝癌细胞凋亡的影响

目的：构建人肝再生增强因子（human augmenter of liver regeneration,hALR）15kD亚型的真核表达系统,并探索ALR对顺铂（Cisplatin,DDP）诱导的人肝癌细胞株QGY凋亡的影响。方法：用聚合酶链反应（polymerase chain reaction,PCR）方法和基因重组技术,从重组质粒pPIC9K-rhALR中扩增出编码rhALR基因片段,将其克隆入pPICZαA质粒中构建重组质粒pPICZα－A-rhALR。重组质粒SacⅠ酶切线性化后电转入酵母GS115中,并在1%的甲醇诱导下表达。表达上清蛋白经Western blot（ALR多克隆抗体和His-tag标签抗体）鉴定和镍柱亲和层析纯化。MTS试剂检测rhALR体外对人肝癌细胞（HepG2、QGY）的促增殖活性,及流式细胞仪检测rhALR在顺铂诱导QGY细胞凋亡中的抗凋亡作用。结果：PCR、双酶切、DNA测序均鉴定重组质粒构建与预期一致。分泌表达的rhALR约占上清总蛋白的70%,目的分子量约17 kD,Western blot均可见单一条带。纯化后的rhALR对HepG2和QGY的体外促增殖作用呈浓度依赖性增强（HepG2组：F=246.729,P=0.000;QGY组：F=246.004,P=0.000）,且在QGY细胞顺铂诱导凋亡时也发挥着浓度梯度式抗凋亡作用（F=101.061,P=0.000）。结论：成功构建高效分泌表达rhALR的pPICZα－A-rhALR GS115真核表达系统;体外实验证实rhALR对顺铂诱导人肝癌细胞有呈浓度依赖性的抗凋亡作用。