Palladium-catalyzed carbonylative cyclization of Baylis-Hillman adducts. An efficient approach for the stereoselective synthesis of 3-alkenyl phthalides

A palladium-mediated carbonylative cyclization reaction of Baylis-Hillman adducts is disclosed. This simple, efficient and straightforward sequence leads to the formation of an array of 3-alkenylphthalides with different substitution patterns on the aromatic ring, with good chemical yields and selectivities.     

The intramolecular reductive cyclization of cyclic enones

The reductive cyclization (electrohydrocyclization reaction) of tethered cyclic enones has been investigated under electrochemical, metal-mediated, and photochemical conditions. The tricyclic products are generally formed with excellent stereoselectivity, particularly if at least one of the enones is β,β-disubstituted.     

乙醇对环糊精葡萄糖基转移酶催化作用的影响

采用紫外吸收光谱法测定了乙醇、环已烷与β-环糊精包合反应稳定常数及自由能变化, 确定乙醇与β-环糊精的包合反应稳定常数K_s=4.71 L/mol, ΔG=-3.84 kJ/mol; 环己烷与β-环糊精包合反应的K_s=19.56 L/mol, ΔG=-7.37 kJ/mol. 环己烷与β-环糊精的结合能力大大高于乙醇, 故用乙醇提高其产率的机理不同于传统工艺中所添加的环己烷. 通过测定乙醇对环糊精葡萄糖基转移酶催化作用的影响进一步探究其作用机理. 结果表明, 乙醇不仅能提高环糊精葡萄糖基转移酶环化作用的活力, 并在一定程度上阻止对转化环糊精有抑制作用的小分子糖的形成, 还可以减轻环糊精葡萄糖基转移酶对环糊精的水解及偶合作用, 从而提高环糊精的产率.     

Synthesis of 5-substituted and 5,6-disubstituted furo[2,3-d]pyrimidines from 2-methylthio-4,6-pyrimidindione and bifunctional electrophiles

A two-step protocol for the synthesis of 5-substituted or 5,6-disubstituted furo[2,3-d]pyrimidines using bifunctional electrophiles and a pyrimidine derivative was developed. The first step is O-alkylation of 2-methylthiopyrimidin-4,6-dione utilizing bifunctional electrophiles which are readily available from the corresponding ketones via bromination or oxidative mesylation procedures. The reaction furnishes 6-(2-oxoethoxy)pyrimidine derivatives in moderate yields, and the di-O-alkylated product, while still unavoidable under the proposed conditions, is easily removed upon recrystallization of the target compound. The second step is intramolecular cyclization of the mono O-alkylated pyrimidines on silica gel to give the target furo[2,3-d]pyrimidines in moderate to good yields.     

Synthesis of pyrone-annulated 2-oxabicyclo[3.3.1]nonanes by palladium-catalyzed cyclization of 4-hydroxy-2-pyrones with allylic bisacetates

Cyclization of 4-hydroxy-2-pyrones with allylic bisacetates by a palladium catalyst is described. Pyrone-annulated 2-oxabicyclo[3.3.1]nonane derivatives were regioselectively produced from the reaction of 4-hydroxy-2-pyrones with 1,4-diacetoxy-2-cyclohexene at high temperature. The reaction would proceed via a migration of the π-allylpalladium intermediate.     

Copper‐Catalyzed Electrophilic Cyclization of N‐Propargylamines with Sodium Sulfinate for the Synthesis of 3‐Sulfonated Quinolines

A convenient and effective protocol for the synthesis of 3‐sulfonated quinolines via copper‐catalyzed electrophilic cyclization of N‐propargylamines has been developed, in which cheap and stable sodium sulfinates were utilized as green sulfonylation reagents. This cascade transformation involves radical addition, cyclization and dehydrogenative aromatization processes in a one‐pot reaction under mild conditions.     

The first synthesis of the anhydrophytosphingosine pachastrissamine (jaspine B) from Garner’s aldehyde

The synthesis of the natural anhydrophytosphingosine pachastrissamine (jaspine B) 1a from Garner’s aldehyde is described.     

New pyrimidine derivatives of cyanimidodithiocarbonates

Summary Several synthetic processes for some new pyrimidine derivatives of cyanimidodithiocarbonates are reported. Due to the formation of by-products, the optimization of reaction conditions is of importance.

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Neue Pyrimidinderivate von Cyanimidodithiocarbonaten

Zusammenfassung Es werden einige Methoden zur Darstellung verschiedener neuer Pyrimidinderivate von Cyanimidodithiocarbonaten vorgestellt. Wegen der Entstehung von Nebenprodukten ist die Optimierung der Reaktionsbedingungen sehr wichtig.

     

2-乙基蒽醌的合成工艺研究

本文以邻苯二甲酸酐和乙苯为原料，采用傅氏酰基化，水解，闭环，蒸馏回收溶剂，氧化还原提纯及乙醇萃取蒸馏技术，合成了高纯度2-乙基蒽醌．     

巴比妥酸在药物合成上的应用

本文综述了巴比妥酸在药物合成上的应用与进展。通过巴比妥酸的烃化、卤化、环化、缩合、光解、螯合等反应得到的一些衍生物具有重要的生理活性，可用作镇静剂、麻醉剂、安眠药、抗肿瘤药、抗菌素等。参考文献２６篇。