Nitrones in Organic Synthesis. Synthesis of Secondary Allyl Amines

Nitrones 1 undergo addition of vinyl organomagnesium bromide to give the allyl hydroxylamines 3 which are easily reduced to the corresponding N-benzyl allyl amines 2.     

靛红衍生的硝酮与酮亚胺的不对称直接氮杂插烯Mannich反应

不对称直接插烯Mannich反应是一类高效构建手性δ-氨基-α,β-不饱和羰基化合物的方法,但这类反应主要局限于以γ-丁烯酸内酯及类似物和α,α-二氰基烯烃等作为亲核试剂前体,因此发展新的插烯亲核试剂尤为重要.本工作报道了一类从靛红衍生且含N-CH结构的硝酮化合物,由于氧化吲哚骨架的强吸电子效应能在温和碱性条件下生成氮杂二烯醇中间体,高效与靛红衍生的亚胺发生直接氮杂插烯Mannich反应.采用金鸡纳碱衍生的手性双功能叔胺硫脲催化剂,以高收率（70%～97%）、高立体选择性（83%～99% ee,>19∶1 dr）合成富官能团化并含相邻季碳-叔碳手性中心的硝酮化合物,且可进一步与缺电烯烃发生[3+2]偶极环加成反应构建含有氢化异噁唑环的吲哚螺环复杂骨架.这类靛红衍生的硝酮作为氮杂插烯亲核试剂可能在不对称合成中具有更为广阔的应用.     

Eco-Friendly One-Pot Synthesis of 2,4-Disubstituted Thiazoles by Grinding Under Catalyst- and Solvent-Free Conditions

Abstract

An efficient and facile synthesis of 2,4-disubstituted thiazoles is achieved by a one-pot reaction of aldehydes and α-bromoketones with thiosemicarbazide by grinding under catalyst- and solvent-free conditions. This method has notable advantages in terms of simple workup, neat conditions, high yield, reasonably rapid reaction rate, and environmental friendliness.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

GRAPHICAL ABSTRACT     

InCl3-Catalyzed,Three-Component Reactions for the Synthesis of Some Novel Functionalized/Annulated Barbituric Acids

Some novel 5-aminoalkylbarbituric acids and corresponding chromene derivatives were synthesized via a one-pot, three-component Mannich reaction starting from 1,3-dimethylbarbituric acid, arylaldehydes, and amines.     

Direct Synthesis of Allyl Amines with 2-Nitrosulfonamide Derivatives via the Tsuji-Trost Reaction

The Tsuji-Trost Reaction is a palladium-catalysed allylation of nucleophiles that consists in the reaction of a nitrogen, carbon or oxygen-based nucleophiles with an allylic substrate bearing a leaving group. Here we present the use of 2-nitrosulfonamide derivatives as nucleophile, which are reactive under mild conditions. 2-nitrosulfonyl groups are well-known dual protective activator groups easy to introduce in any type of amine substrates. The resulting 2-nitrosulfonamide derivatives are ideal substrates for the Tsuji-Trost reaction to afford a convenient and flexible access to primary and dissymmetric secondary allyl amines. The optimised procedure is flexible (for solvent, temperature, functional groups) and has been applied with good to excellent yield to access to a wide range of allyl amine derivatives.     

A Convenient Method for the Preparation of N-Aryl and N-Alkyl-O-Methyl Hydroxylamines

Trifluoroaceto or p-nitrobenzo-N-substituted hydroxamic acids are smoothly methylated with diazomethane and the products cleanly cleaved by hydrazine to provide the title compounds.     

光催化氧化还原体系中硝酮与芳香叔胺的自由基偶联反应

通过氮α-位碳自由基构造氮α-位碳-碳键是合成含氮有机化合物的重要方法. 近期, 利用可见光催化氧化芳香叔胺—氮α-位去质子化形成氮α-位碳自由基的原理发展了一系列新颖的自由基加成(偶联)反应, 成为氮α-位碳自由基化学发展的重要方向. 本文应用Ir-催化剂, 实现了光催化氧化还原体系中硝酮与芳香叔胺的自由基偶联反应, 高效地合成β-氨基羟胺化合物. 该反应条件温和、操作简单, 具有较高的原子经济性, 且对于各种链状、环状以及手性硝酮都具有良好的适用性, 产物可方便地转化为重要的邻二胺化合物.     

A New Method for the Synthesis of Allyl Arylselenides via the Reaction of the Zinc Allyl Selenoates with Diaryliodonium Salts

The insertion of elemental selenium into the Zn-C bond of allylzinc bromide in THF leads to the corresponding zinc allyl selenoate. It reacts with diaryliodonium salts in THF-HMPA to afford the allyl arylselenides in high yields.     

A Novel Method for Biomimetic Synthesis of Mannich Bases

Since the early studies of Mannich, Mannich reaction has become an important tool for the synthesis of new compounds. Mannich bases can be either directly employed or used as intermediates. In this work, the one‐carbon unit transfer reaction of tetrahydrofolate coenzyme was initiated. 1,3‐Dimethylimidazolidine as a new tetrahydrofolate coenzyme model at formaldehyde oxidation level was used to react with ketone having active hydrogen atoms and amine to give the corresponding Mannich base in good yield by a covert Mannich reaction. A novel method for biomimetic synthesis of various Mannich bases is provided.     

A Facile Method for the Synthesis of 4- Acetylaminobenzo[15]crown-5

The 4-acetylaminobenzo[15]crown-5 is an important intermediate in the synthesis of crown ether cyanine dyes1, in addition, the acetylamino can easily be hydrolyzed to be amine2, to our knowledge which also is an usful intermediate3,4, The classical procedure for the synthesis of 4-acetylaminobenzo[15]crown-5 involves several steps2,5: typically nitration of the benzo[15]crown-5, followed by reduction of the introduced nitro group to form amine, and finally, acylation of the amine to give the am…     

Convenient Synthesis of Oxazolidinones and Oxazinones from Allyl and Homoallyl Amines under Mild Conditions

An efficient one‐pot general method for the high‐yield synthesis in solution of oxazolidinones and oxazinones from allyl‐ and homoallylamines, respectively, has been developed. The reaction is carried out at an atmospheric pressure between 0°C and room temperature using a solution of carbon dioxide in acetonitrile and hindered guanidine as the base.     

A New Method for the Facile Synthesis of Hydroxylated Flavones by Using Allyl Protection

The iodine‐induced oxidative cyclization of 2′‐hydroxychalcones provides a simple, highly efficient approach to various hydroxy flavones and analogues. This process is run under mild conditions, tolerates various functional groups, and provides hydroxy flavones in good to excellent yield. The allyl‐protected acetophenones and benzaldehydes were smoothly deallylated under similar conditions.     

A General Method for the Synthesis of 11-Deoxyanthracyclinones

A general method for the synthesis of 11-deoxyanthracyclinones is described.     

A General Method for N‐Methylation of Amines and Nitro Compounds with Dimethylsulfoxide

DMSO methylates a broad range of amines in the presence of formic acid, providing a novel, green and practical method for amine methylation. The protocol also allows the one‐pot transformation of aromatic nitro compounds into dimethylated amines in the presence of a simple iron catalyst.     

阿法替尼的合成工艺改进

以2-氨基-4-氯苯甲酸为原料,经环合、硝化、氯代和胺化后,采用一锅两步法制得关键中间体4-［(3-氯-4-氟苯基)氨基］-6-硝基-7-［(S)-四氢呋喃-3-基氧基]-喹唑啉(4); 4依次经还原、酰胺化、HWE反应合成阿法替尼,总收率55.7%,含量98%,其结构经¹H NMR和LC-MS确证。     

A General Strategy for the Catalytic,Highly Enantio‐ and Diastereoselective Synthesis of Indolizidine‐Based Alkaloids

Sixteen indolizidine‐based alkaloids (IBAs) that were isolated as poison constituents of the skin of frogs were synthesized in a highly flexible and stereoselective manner. As a key step, a three‐component, organocatalytic, highly enantio‐ and diastereoselective vinylogous Mukaiyama–Mannich reaction was employed furnishing optically highly enriched butyrolactams as central intermediates on a multigram scale. The attached six‐membered ring was constructed through cyclization of the pendant enoate moiety onto the pyrrolidine ring. The absolute configuration of the bridgehead chiral center and the adjacent 8‐position was established in the initial vinylogous Mannich reaction, whereas the 3‐ and 5‐substituents were introduced through organometallic addition at a late stage of the synthesis with full stereochemical control from the substrate. With this strategy, simple as well as even more complex alkaloids were accessible in good overall yields as single stereoisomers. These syntheses also served to establish the absolute and relative configuration of those IBAs that had never been synthesized before.