A synergistic catalytic effect between copper methanesulfonate and acetic acid in tetrahydropyranylation of alcohols and phenol at room temperature under solvent free condition has been described. Both alcohols （prim...A synergistic catalytic effect between copper methanesulfonate and acetic acid in tetrahydropyranylation of alcohols and phenol at room temperature under solvent free condition has been described. Both alcohols （primary, secondary and tertiary） and phenols reacted with 3,4-dihydro-2H-pyran smoothly to afford the corresponding tetrahydropyranyl ethers in good yields.展开更多
Alcohols are selectively and efficiently protected as their tetrahydropranyl ethers in the presence of a catalytic amount of Fe（HSO4）3 in good to high yields. All reactions are performed under mild and completely he...Alcohols are selectively and efficiently protected as their tetrahydropranyl ethers in the presence of a catalytic amount of Fe（HSO4）3 in good to high yields. All reactions are performed under mild and completely heterogeneous reaction conditions.展开更多
A simple, green and efficient method for the DHP protection of various alcohols and phenols and the subsequent removal of the corresponding protective group in the presence of a catalytic amount of the activated carbo...A simple, green and efficient method for the DHP protection of various alcohols and phenols and the subsequent removal of the corresponding protective group in the presence of a catalytic amount of the activated carbon supported H2SO4 is described.展开更多
Desymmetrization reactions provide a powerful approach for the construction of complex molecules. Various methods have been developed for the selective monoprotection of symmetrical diols;however, their application to...Desymmetrization reactions provide a powerful approach for the construction of complex molecules. Various methods have been developed for the selective monoprotection of symmetrical diols;however, their application to large-scale operations is limited. In this study, the monotetrahydropyranylation of symmetrical diols in a flow reactor has been developed, whereby the length of the flow reactor tube and the amount of acid were optimized. A higher selectivity for the monoprotected derivative was observed when the reaction was performed in a flow reactor compared with that observed in a conventional batch experiment. The efficient flow method developed herein can be applied to large-scale synthesis by numbering up the flow reactor without affecting the selectivity and yield. Since monoprotection can be achieved without using a large excess of diol, our developed flow method is effective when expensive diol must be used.展开更多
以氢氧化铝和甲烷磺酸(MS-H)为原料,用水热法合成了六水合甲基磺酸铝([Al(H_2O)_6][MS]_3),将其在265℃焙烧5 h得到无水甲基磺酸铝[Al_2(OH)(MS)_5]。通过元素分析和红外光谱分析确定了二者的结构组成。热重分析和固体核磁27Al MAS NMR...以氢氧化铝和甲烷磺酸(MS-H)为原料,用水热法合成了六水合甲基磺酸铝([Al(H_2O)_6][MS]_3),将其在265℃焙烧5 h得到无水甲基磺酸铝[Al_2(OH)(MS)_5]。通过元素分析和红外光谱分析确定了二者的结构组成。热重分析和固体核磁27Al MAS NMR分析表明,六水合甲基磺酸铝在265~365℃热分解过程中发生部分水解,生成的羟基结构在两个金属铝原子中间形成桥连。以室温下催化正丁醇的四氢吡喃化反应为探针,考察了Al_2(OH)(MS)_5的催化性能,并测定其重复使用性。结果表明:当n(正丁醇)∶n(3,4-二氢吡喃)=1.0∶1.1(正丁醇15 mmol)、催化剂用量为3.34%(以正丁醇物质的量计)、二氯甲烷为10 mL、反应温度为25℃、反应时间为45 min时,反应的转化率可达到100%。重复使用5次后,转化率仍可达90%。通过与其他铝盐催化剂相比,Al_2(OH)(MS)_5催化活性最高。对其吸水和催化机理进行了研究,表明Al_2(OH)(MS)_5的Al^(3+)与DHP和醇形成配位过渡态是催化反应进行的关键。展开更多
{[K.18-Crown-6]Br3}n,a unique tribromide-type catalyst,was utilized for the N-boc protection of amines and trimethylsilylation(TMS)and tetrahydropyranylation(THP)of alcohols.The method is general for the preparation o...{[K.18-Crown-6]Br3}n,a unique tribromide-type catalyst,was utilized for the N-boc protection of amines and trimethylsilylation(TMS)and tetrahydropyranylation(THP)of alcohols.The method is general for the preparation of N-boc derivatives of aliphatic(acyclic and cyclic)and aromatic,and primary and secondary amines and also various TMS-ethers and THP-ethers.The simple separation of the catalyst from the product is one of the many advantages of this method.展开更多
Polystyrene supported TiCI4 （Ps-TiCI4） and polystyrene supported FeC13 （Ps-FeC13） were prepared by coordi- nating Lewis acids with polystyrene. The catalysts were characterized by TGA, BET, SEM, IR and pyri- dine-...Polystyrene supported TiCI4 （Ps-TiCI4） and polystyrene supported FeC13 （Ps-FeC13） were prepared by coordi- nating Lewis acids with polystyrene. The catalysts were characterized by TGA, BET, SEM, IR and pyri- dine-adsorbed IR. The loading of Ps-TiC14 and Ps-FeCI3 were 0.35 and 0.3 mmol.g-1 respectively. Both catalysts were found to be efficient for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols in different solvents. Two catalysts can be recovered and reused for five times with good activity.展开更多
A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on...A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on NaHSO4.H2O under solvent-free conditions is reported.展开更多
An easy preparation of tetrahydropyranyl (THP) ethers of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) in refluxing dichloromethane has been carried out in good to excellent yields under catalysis of anhydrous ...An easy preparation of tetrahydropyranyl (THP) ethers of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) in refluxing dichloromethane has been carried out in good to excellent yields under catalysis of anhydrous ferrous sulfate.展开更多
文摘A synergistic catalytic effect between copper methanesulfonate and acetic acid in tetrahydropyranylation of alcohols and phenol at room temperature under solvent free condition has been described. Both alcohols （primary, secondary and tertiary） and phenols reacted with 3,4-dihydro-2H-pyran smoothly to afford the corresponding tetrahydropyranyl ethers in good yields.
文摘Alcohols are selectively and efficiently protected as their tetrahydropranyl ethers in the presence of a catalytic amount of Fe（HSO4）3 in good to high yields. All reactions are performed under mild and completely heterogeneous reaction conditions.
基金the special research project of the National 973 Foundation of China(No.2006CB708606)the National Natural Science Foundation of China(No.20562010)
文摘A simple, green and efficient method for the DHP protection of various alcohols and phenols and the subsequent removal of the corresponding protective group in the presence of a catalytic amount of the activated carbon supported H2SO4 is described.
文摘Desymmetrization reactions provide a powerful approach for the construction of complex molecules. Various methods have been developed for the selective monoprotection of symmetrical diols;however, their application to large-scale operations is limited. In this study, the monotetrahydropyranylation of symmetrical diols in a flow reactor has been developed, whereby the length of the flow reactor tube and the amount of acid were optimized. A higher selectivity for the monoprotected derivative was observed when the reaction was performed in a flow reactor compared with that observed in a conventional batch experiment. The efficient flow method developed herein can be applied to large-scale synthesis by numbering up the flow reactor without affecting the selectivity and yield. Since monoprotection can be achieved without using a large excess of diol, our developed flow method is effective when expensive diol must be used.
文摘以过渡金属甲基磺酸盐[Mn(CH3SO3)2·2H2O,Cu(CH3SO3)2·4H2O,Co(CH3SO3)2·4H2O和Zn(CH3SO3)2·4H2O]为催化剂,在室温条件下催化醇的四氢吡喃化反应,并对反应条件进行了优化。结果表明:当醇用量为30 mmol,醇和3,4-二氢吡喃摩尔比为1.0∶1.1,甲基磺酸盐用量为1 mmol,二氯甲烷20 m L时,可高效催化醇的四氢吡喃化反应。与路易斯酸催化活性相比,过渡金属甲基磺酸盐催化醇的四氢吡喃化反应效果最好,催化酚的效果较差。用Mn(CH3SO3)2·2H2O和Cu(CH3SO3)2·4H2O催化正丁醇的四氢吡喃化反应,重复使用5次,收率分别为89%和92%。
基金support for this work from the research affairs of Hamedan University of Medical Sciences,Hamedan,I.R.Iranpartial support of this work by the Research Affairs Office of Bu-Ali Sina UniversityCenter of Excellence in Development of Chemical Method(CEDCM)Hamedan,I.R.Iran
文摘{[K.18-Crown-6]Br3}n,a unique tribromide-type catalyst,was utilized for the N-boc protection of amines and trimethylsilylation(TMS)and tetrahydropyranylation(THP)of alcohols.The method is general for the preparation of N-boc derivatives of aliphatic(acyclic and cyclic)and aromatic,and primary and secondary amines and also various TMS-ethers and THP-ethers.The simple separation of the catalyst from the product is one of the many advantages of this method.
文摘Polystyrene supported TiCI4 （Ps-TiCI4） and polystyrene supported FeC13 （Ps-FeC13） were prepared by coordi- nating Lewis acids with polystyrene. The catalysts were characterized by TGA, BET, SEM, IR and pyri- dine-adsorbed IR. The loading of Ps-TiC14 and Ps-FeCI3 were 0.35 and 0.3 mmol.g-1 respectively. Both catalysts were found to be efficient for the tetrahydropyranylation and detetrahydropyranylation of various alcohols and phenols in different solvents. Two catalysts can be recovered and reused for five times with good activity.
文摘A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on NaHSO4.H2O under solvent-free conditions is reported.
文摘An easy preparation of tetrahydropyranyl (THP) ethers of alcohols and phenols with 3,4-dihydro-2H-pyran (DHP) in refluxing dichloromethane has been carried out in good to excellent yields under catalysis of anhydrous ferrous sulfate.
