Phosphomolybdic acid-supported silica gel as efficient and cost-effective solid acid for the benzylation of indoles with benzylic alcohols

Indoles undergo smooth alkylation with benzylic alcohols on the surface of 10 mol% of phosphomolybdic acid supported on silica gel under mild conditions to produce C-3 benzylated-indoles in high yields and with high selectivity. This method offers significant advantages such as high conversions, short reaction times, mild reaction conditions, cleaner reaction profiles, high selectivity and low cost of the heterogeneous catalyst.     

Mild and efficient method for the cleavage of cyclic and acyclic ethers by iodine under solvent-free conditions

Ethers undergo smooth cleavage with acyl chlorides in the presence of a catalytic amount of elemental iodine under extremely mild conditions to give the corresponding halo esters. This new procedure offers significant advantages such as high conversions, short reaction times and enhanced selectivity together with mild reaction conditions, which makes it an attractive strategy.     

单原子催化甲烷直接转化的研究进展

将甲烷直接转化(DMC)为高附加值化学品(如甲醇等化合物),是实现天然气高效利用的有效途径.因甲烷结构非常稳定,使其在温和条件下(反应温度≤150℃的非强酸介质体系)的高效活化极具挑战性.近年来,单原子催化剂(SACs)因其活性物种的高利用率和高选择性,已引起国内外研究者的广泛关注,并被尝试应用于多种反应.研究表明, SACs在DMC反应中表现出独特的催化性能.本综述中,我们总结了在温和条件下, SACs在DMC反应中的研究进展,重点针对热催化反应过程的催化剂设计和反应路径研究进行了归纳和分析.此外,还对光催化反应过程中涉及的SACs上的DMC反应进行了分析.最后,对温和条件下实现DMC进行了总结和展望.     

An Approach to Disulfide Synthesis Promoted by Sulfonyl Chloride in Sodium Bicarbonate Aqueous Media

A mild and efficient protocol for the synthesis of disulfides in aqueous media using mercaptans promoted by sulfonyl chloride is reported. This reaction offers the advantages of mild reaction conditions, short reaction time, high yields, and simple operation.     

Practical and regioselective brominations of aromatic compounds using tetrabutylammonium peroxydisulfate

Direct bromination of wide range of aromatic compounds substituted with electron donating groups such as methoxy, hydroxy, or amino groups have been achieved with high regioselectivity by the reaction with Br₂ in the presence of tetrabutylammonium peroxydisulfate 1 under mild conditions in acetonitrile in excellent yields. The use of lithium bromide as a bromination reagent afforded high yields of monobromo compounds with complete regioselectivity under neutral and mild reaction conditions in acetonitrile.     

(Tosylimino)phenyl-λ3-iodane as a reagent for the synthesis of methyl carbamates via Hofmann rearrangement of aromatic and aliphatic carboxamides

A new, mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides using (tosylimino)phenyl-λ(3)-iodane, PhINTs, as a reagent is reported. Because of the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides, which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates or their subsequent conversion to stable carbamates by treatment with alcohols.     

Converting wastes into added value products: from glycerol to glycerol carbonate, glycidol and epichlorohydrin using environmentally friendly synthetic routes

Glycerol carbonate, synthesised via a non-phosgene route using glycerol and CO₂ or urea in presence of a heterogeneous catalyst, was efficiently converted into a series of derivatives through the functionalization of the -OH moiety, using high yield, high selectivity synthetic routes not affecting the carbonate functionality. So, for example, glycerol carbonate was converted into epichlorohydrin, a product that has a large industrial application, under very mild conditions, using a two-step reaction with a 98% yield and 100% selectivity. The high yield and mild reaction conditions (very often close to the ambient conditions) make the environmentally friendly synthetic approach described in this work of potential applicative interest. All compounds prepared were fully characterized.     

Facile N-derivatization of alpha-amino esters and amides via benzotriazolylmethyl derivatives

Alpha-(N-substituted amino)esters were prepared in a two-step procedure from available unsubstituted alpha-amino esters. alpha-Amino esters are first converted into the corresponding N-benzotriazolylmethyl derivatives; in the second step, the benzotriazole group is substituted by various nucleophiles with or without the presence of a Lewis acid to give substituted alpha-amino esters in high overall yield under mild conditions with no signs of racemization. Boc-protected amino acids were converted into alpha-amino amides; subsequent deprotection allowed the conversion into N-substituted derivatives analogously to the alpha-amino esters, without racemization in high yields under mild conditions.     

LiOH-Catalyzed Simple Ring Opening of Epoxides Under Solvent-Free Conditions

LiOH has been found to be a very simple and selective catalyst for the rapid and mild synthesis of β-hydroxy sulfides and β-hydroxyl nitriles by ring opening of epoxides with aromatic, aliphatic, and heterocyclic thiols and trimethylsilyl cyanide at room temperature under solvent free conditions. All the reactions proceeded satisfactorily in short times and afforded the corresponding products in good to excellent yields with high regioselectivity and chemoselectivity under mild reaction conditions.     

Phosphine‐Catalyzed Asymmetric Umpolung Addition of Trifluoromethyl Ketimines to Morita–Baylis–Hillman Carbonates

A novel phosphine‐catalyzed, highly enantioselective umpolung addition of trifluoromethyl ketimines to Morita–Baylis–Hillman carbonates was developed and it provides facile access to optically active trifluoromethyl amines with a chiral tertiary stereocenter under mild reaction conditions. The salient features of this reaction include general substrate scope, mild reaction conditions, good yields, high enantioselectivity, ease of scale‐up to gram scale, and further transformations of the products.     

原子级分散Fe-N-C温和条件下选择性氧化催化特性

采用非溶液法制备了原子级分散的Fe-N-C催化剂, 并用于硫醚和二级醇的选择性氧化. 研究结果表明, 这种原子级分散的Fe-N-C催化剂可在温和条件下选择性地将硫醚转化为亚砜, 而不会产生过度氧化的砜. 该工艺具有反应条件温和、 反应速度快、 收率高等优点; 该催化剂对二级醇氧化制酮反应具有较高的催化活性, 产率较高. 作为一种非均相催化剂, Fe-N-C催化剂循环使用5次后活性未见显著下降; 在实验结果和参考文献的基础上还提出了一种可能的自由基反应机理.     

An Efficient Synthesis of 4‐Naphthylpyrimidin‐2‐amine Derivatives under Solvent‐Free Conditions

A simple, efficient, and mild protocol for the synthesis of 4‐naphthylpyrimidin‐2‐amine derivatives under solvent‐free conditions by the reaction of aromatic aldehydes (or 1‐naphthaldehyde), 2‐acetylnaphthalene (or aromatic ketones), guanidine carbonate, and sodium hydroxide was reported. The advantages of this protocol include short reaction time, mild reaction conditions, easy workup, high yields, and environmental friendliness.     

ZnO as a new catalyst for N-formylation of amines under solvent-free conditions

The treatment of amines with formic acid in the presence of ZnO under solvent-free conditions brings about highly and efficient N-formylation to give the corresponding formamides in excellent yields. The N-formylation reaction not only involves mild conditions, simple operation, and high yields but also high chemoselectivity.     

钯络合物在有机合成中的一些应用

钯络合物能催化许多反应,在有机合成中有着广泛的应用。钯催化下的反应,产率高,选择性好,反应条件温和。本文介绍了近年来该类反应在有机合成中的一些应用。     

Highly efficient synthesis of polysubstituted fluorene via iron-catalyzed intramolecular Friedel-Crafts alkylation of biaryl alcohols

An efficient and mild Fe(III)-catalyzed intramolecular Friedel-Crafts alkylation of biaryl methanol derivatives has been developed to achieve the substituted fluorene derivatives. The present reaction provides an excellent alternative to published methods because of its high yields, operational simplicity, mild conditions, and use of inexpensive and sustainable catalyst.     

A novel Prins-alkynylation reaction for the synthesis of 4-phenacyl tetrahydropyrans

Aldehyde, homoallylic alcohol, and alkyne undergo smooth Prins-type cyclization in the presence of BF₃·OEt₂/CuCl (10 mol % each) in dichloromethane under mild reaction conditions to afford 4-phenacyl tetrahydropyran derivatives in good yields. This method is highly stereoselective, affording cis-tetrahydropyrans exclusively. The salient features of this method are high conversions, mild reaction conditions, short reaction times, high selectivity, and operational simplicity.     

Cationic palladium complex catalyzed highly enantioselective intramolecular addition of arylboronic acids to ketones. A convenient synthesis of optically active cycloalkanols

An efficient and convenient synthesis of optically active cycloalkanols by utilizing the chiral cationic palladium complex as the catalyst was achieved in mild conditions with high yield and high enantioselectivity.     

Use of an aminosilyllithium for the diastereoselective synthesis of diphenyl oxasilacyclopentane acetals and polyols

[reaction: see text] The conjugate addition reaction of a stable, in situ generated silyllithium gives a beta-hydroxysilyl ester with high diastereoselectivity. Conversion of the beta-hydroxysilyl ester to a beta-fluorosilyl ester affords the precursor to the oxasilacyclopentane acetal in high yields under mild conditions. A hydride reduction and subsequent intramolecular silylation lead to the acetal in excellent yields. Finally, highly selective nucleophilic substitution affords oxasilacyclopentanes, which undergo a mild oxidation to afford 1,3-trans diols with high selectivity.     

锰配合物催化1,3-丁二烯环氧化合成环氧丁烯

合成了N,N′-dimethyl-N,N′-bis(2-pyridylmethyI)ethane-1,2-diamine(mep)及其相应的锰配合物,并将其锰配合物用于1,3-丁二烯的环氧化反应,高选择性的合成单环氧化合物环氧丁烯,考察了各因素对反应的影响,在优化的条件下能达到90%左右的收率和大于99%的选择性.在该...     

Preparation of Silyl Ethers Using Hexamethyldisilazane in the Presence of N‐Bromosuccinimide under Mild and Solvent‐Free Conditions

A mild, simple, novel and highly efficient method for the rapid protection of various primary, secondary, tertiary aliphatic and aromatic alcohols using hexamethyldisilazane (HMDS) in the presence of N-bromosuccinimide (NBS) as an active, inexpensive, non-toxic and readily available catalyst under solvent-free conditions is described. Trimethylsilyl ethers were prepared in high to excellent yields with short reaction time under mild and almost neutral reaction conditions.