2-氰基苄基诱导的葡萄糖醛酸β糖苷键立体选择性

以2,3-O-(2-氰基苄基)-4-O-氯乙酰基-β-对甲基苯基-D-葡萄糖醛酸硫苷等7个单糖模块作为糖基供体,以甲醇等醇类化合物作为糖基受体,分别在二氯甲烷和甲苯溶剂中进行了糖基化反应,研究了葡萄糖醛酸C2位引入2-氰基苄基(BCN)以及溶剂效应对糖苷键α/β选择性的影响.通过对糖基产物的1H NMR,13C NMR和HSQC等谱图分析发现, BCN可以有效提高糖苷键的β选择性,其中部分糖基化产物的糖苷键α/β比例最高可达1/50.为磺达肝癸钠分子中葡萄糖醛酸的β糖苷键的构建方法做出了初步探索.

Efficient oxidation of cinnamon oil to natural benzaldehyde over β-cyclodextrin-functionalized MWCNTs

We have designed and prepared β-cyclodextrin （β-CD）-functionalized multi-walled nanotubes （MWCNTs-g-CD） for the oxidation of cinnamon oil to natural benzaldehyde under aqueous condi- tions. The synergistic effect of combining MWCNTs with β-CD led to a remarkable increase in the performance of the MWCNTs-g-CD for the catalytic oxidation of cinnamaldehyde, which exhibited 95% cinnamaldehyde conversion and 85% selectivity to natural benzaldehyde with a short reaction time of 10 rain. The MWCNTs-g-CD also exhibited outstanding recyclability with good stability, showing no discernible decrease in their catalytic activity over five reaction cycles.

Enantioselective extraction of clorprenaline enantiomers with hydrophilic selector of sulfobutylether-β-cyclodextrin by experiment and modeling

Enantioselective extraction of hydrophobic clorprenaline （CPE） enantiomers from organic phase to aqueous phases with sulfobutylether-β-cyclodextrin （SBE-β-CD） as the selector was investigated with insight into a number of important process variables, such as the type of organic solvent, concentration of selector, pH, and temperature. Equilibrium of the extraction system was modeled using a reactive extraction modcl with a homogeneous aqueous phase reaction. The important parameters of this model were determined experimentally. The physical distribution coefficients for molecular and ionic CPE were determined as 0.3 and 8.93, respectively. The equilibrium constants of the complexation reaction with SBE-β-CD were determined as 152 and 110 L/mol for R- and S-CPE, respectively. Results show that the experimental data agree with the model predictions perfectly. Comprehensively considering the experiment and model, the extraction conditions are optimized and the best extraction conditions are： pH of 6.0, SBE-β-CD concentration of 0.04 tool/L, and temperature of 5 ℃, providing the enantioselectivity （a） of 1.25, the fraction of R-CPE （φR） in aqueous phase of 0.71 and performance factor （pf） of 0.025.

(4S,4'S)-2,2'-(4,6-Dibenzofurandiyl)bis[4,5-dihydro-4-phenyloxazole]-Ni(Ⅱ)Complexes Catalyzed Highly Enantioselective Nitrile Imine Cycloaddition Reactions

The Ni(Ⅱ)-chiral(4S,4'S)-2,2'-(4,6-dibenzofurandiyl)bis[4,5-dihydro-4-phenyloxazole](DBFOX/Ph)-catalyzed asymmetric 1,3-dipolar cycloadditions of nitrile imines to N-α,β-unsaturated acylpyrazoles was presented.This tactic rendered a facile and feasible route to prepare the optically active tetrasubstituted 5-3,5-dimethylpyrazole acyl dihydropyrazole cy-cloadducts bearing one or two contiguous stereocenters in good yields(up to 97%yield)with high regioselectivities(100%)and enantioselectivities(up to 97.5%ee).Following that,chiral cycloadducts could be obtained consistently in good chemical yields with excellent enantioselectivities within the gram scale process,additionally,toward five kinds of derivatization reac-tions like nucleophilic and reduction for further conversion of chiral cycloadducts to related chiral dihydropyrazole derivatives encompassing different substituents.

Recent advances in the management of variceal bleeding

Acute haemorrhage from ruptured gastroesophageal varices is perhaps the most serious consequence of uncontrolled portal hypertension in cirrhotic patients.It represents a medical emergency and is associated with a high morbidity and mortality.In those who survive the initial bleeding event,the risks of further bleeding and other decompensated events remain high.The past 30 years have seen a slow evolution of management strategies that have greatly improved the chances of surviving a variceal haemorrhage.Liver cirrhosis is a multi-staged pathological process and we are moving away from a one-size-fits-all therapeutic approach.Instead there is an increasing recognition that a more nuanced approach will yield optimal survival for patients.This approach seeks to risk stratify patients according to their disease stage.The exact type and timing of treatment offered can then be varied to suit individual patients.At the same time,the toolbox of available therapy is expanding and there is a continual stream of emerging evidence to support the use of endoscopic and pharmacological therapies.In this review,we present a summary of the treatment options for a variety of different clinical scenarios and for when there is failure to control bleeding.We have conducted a detailed literature review and presented up-to-date evidence from either primary randomized-controlled trials or meta-analyses that support current treatment algorithms.

Novel treatment options for portal hypertension

Portal hypertension is most frequently associated with cirrhosis and is a major driver for associated complications,such as variceal bleeding,ascites or hepatic encephalopathy.As such,clinically significant portal hypertension forms the prelude to decompensation and impacts significantly on the prognosis of patients with liver cirrhosis.At present,non-selective bblockers,vasopressin analogues and somatostatin analogues are the mainstay of treatment but these strategies are far from satisfactory and only target splanchnic hyperemia.In contrast,safe and reliable strategies to reduce the increased intrahepatic resistance in cirrhotic patients still represent a pending issue.In recent years,several preclinical and clinical trials have focused on this latter component and other therapeutic avenues.In this review,we highlight novel data in this context and address potentially interesting therapeutic options for the future.

Variceal bleeding in cirrhotic patients

Variceal bleeding is one of the major causes of death in cirrhotic patients.The management during the acute phase and the secondary prophylaxis is well defined.Recent recommendations(2015 Baveno VI expert consensus)are available and should be followed for an optimal management,which must be performed as an emergency in a liver or general intensive-care unit.It is based on the early administration of a vasoactive drug(before endoscopy),an antibiotic prophylaxis and a restrictive transfusion strategy(hemoglobin target of 7 g/dL).The endoscopic treatment is based on band ligations.Sclerotherapy should be abandoned.In the most severe patients(Child Pugh C or B with active bleeding during initial endoscopy),transjugular intrahepatic portosystemic shunt(TIPS)should be performed within 72 hours after admission to minimize the risk of rebleeding.Secondary prophylaxis is based on the association of non-selective beta-blockers(NSBBs)and repeated band ligations.TIPS should be considered when bleeding reoccurs in spite of a well-conducted secondary prophylaxis or when NSBBs are poorly tolerated.It should also be considered when bleeding is refractory.Liver transplantation should be discussed when bleeding is not controlled after TIPS insertion and in all cases when liver function is deteriorated.