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The reactions of the heterocyclic imines 5,6‐dihydro‐2H‐[1,3]oxazines and 2H‐1,4‐benzothiazines with different substituted acetyl chlorides in the presence of triethylamine forming β‐lactams were examined focusing on the stereochemistry of the Staudinger reaction. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(28):8318-8322
The nickel(0)‐catalyzed carbonylative cycloaddition of 1,5‐ and 1,6‐ene‐imines with carbon monoxide (CO) is reported. Key to this reaction is the efficient regeneration of the catalytically active nickel(0) species from nickel carbonyl complexes such as [Ni(CO)3L]. A variety of tri‐ and tetracyclic γ‐lactams were thus prepared in excellent yields with 100 % atom efficiency. Preliminary results on asymmetric derivatives promise potential in the synthesis of enantioenriched polycyclic γ‐lactams. 相似文献
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Indium Tribromide Catalyzed Coupling Reaction of Enol Ethers with Silyl Ketene Imines toward the Synthesis of β,γ‐Unsaturated Nitriles 下载免费PDF全文
Dr. Yoshihiro Nishimoto Takashi Nishimura Prof. Dr. Makoto Yasuda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18301-18308
Herein, a coupling reaction of enol ethers with silyl ketene imines in the presence of catalytic amounts of InBr3 and Me3SiBr is described. Kinetic studies have revealed that an indium catalyst and Me3SiBr accelerated the coupling process and the regeneration of the catalyst, respectively. Various types of enol ethers and silyl ketene imines are applicable. In addition, a formal synthesis of verapamil was achieved by using this novel coupling reaction. 相似文献
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Chemoselective Synthesis of β‐Amino Ester or β‐Lactam via Sonochemical Reformatsky Reaction 下载免费PDF全文
A series of β‐amino esters were synthesized by the reaction of N‐tosyl aldimine or N‐hydroxy aldimine with bromoacetate by sonochemical Reformatsky reaction. The β‐N‐hydroxyamino ester was obtained and the formed sensitive hydroxylamino functionality was resistant under the reaction condition. The β‐lactam also was synthesized by the reaction of N‐p‐methoxy aldimine as reacting substrate under this sonochemical Reformatsky reaction condition. 相似文献
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Synthesis of Pyrrolidines and Pyrrolizidines with α‐Pseudoquaternary Centers by Copper‐Catalyzed Condensation of α‐Diazodicarbonyl Compounds and Aryl γ‐Lactams 下载免费PDF全文
Dr. Sébastien Goudedranche Dr. Céline Besnard Léo Egger Prof. Jérôme Lacour 《Angewandte Chemie (International ed. in English)》2016,55(44):13775-13779
N‐aryl γ‐lactams react intermolecularly with acceptor–acceptor diazo reagents, usually dicarbonyl compounds, in a copper‐catalyzed process to yield functionalized pyrrolidines with α‐pseudoquaternary centers. As 1,2‐acyl or ‐phosphoryl migration is preferred, single regioisomers are obtained. Furthermore, in the presence of a Lewis acid, subsequent Friedel–Crafts reactions yield tricyclic pyrrolizidines in excellent yields (90–96 %) and diastereoselectivities (up to >20:1). 相似文献
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Stereoselective Synthesis of Functionalized Pyrrolidines by the Diverted N−H Insertion Reaction of Metallocarbenes with β‐Aminoketone Derivatives 下载免费PDF全文
Simon M. Nicolle Dr. William Lewis Prof. Dr. Christopher J. Hayes Prof. Dr. Christopher J. Moody 《Angewandte Chemie (International ed. in English)》2016,55(11):3749-3753
A highly stereoselective route to functionalized pyrrolidines by the metal‐catalyzed diverted N?H insertion of a range of diazocarbonyl compounds with β‐aminoketone derivatives is described. A number of catalysts (rhodium(II) carboxylate dimers, copper(I) triflate, and an iron(III) porphyrin) are shown to promote the process under mild conditions to give a wide range of highly substituted proline derivatives. The reaction starts as a metallocarbene N?H insertion but is diverted by an intermolecular aldol reaction. 相似文献
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γ‐Halocarbanions, short‐lived intermediates, add to electron‐deficient double bonds of aldehydes, Michael acceptors, and imines to form anionic adducts that enter intramolecular 1,5‐substitution to form five‐membered rings of tetrahydrofurans, cyclopentanes, and pyrrolidines, respectively. Although the γ‐halocarbanions can be generated by simple deprotonation of appropriate precursors, a wealth of other methods based on Lewis acid‐catalyzed opening of cyclopropanes with formation of dipolar species utilizes a similar mechanistic scheme. In our review, we analyze kinetic relations of elementary processes in the multistep transformations, and demonstrate how structural factors influence the mechanisms and selectivity of the reaction. 相似文献
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Xiaohong Chen Yin Zhu Zhen Qiao Mingsheng Xie Lili Lin Dr. Xiaohua Liu Dr. Xiaoming Feng Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(33):10124-10129
An easily available and efficient chiral N,N′‐dioxide–nickel(II) complex catalyst has been developed for the direct catalytic asymmetric aldol reaction of α‐isothiocyanato imide with aldehydes which produces the products in morderate to high yields (up to 98 %) with excellent diastereo‐ (up to >99:1 d.r.) and enantioselectivities (up to >99 % ee). A variety of aromatic, heteroaromatic, α,β‐unsaturated, and aliphatic aldehydes were found to be suitable substrates in the presence of 2.5 mol % L ‐proline‐derived N,N′‐dioxide L5 –nickel(II) complex. This process was air‐tolerant and easily manipulated with available reagents. Based on experimental investigations, a possible transition state has been proposed to explain the origin of reactivity and asymmetric inductivity. 相似文献
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A series of homoallyl β′,γ′-unsaturated amines were synthe sized via 1,2-addition of α,β-unsaturated imines with allylsamarium bromide in excellent yields under mild and neutral conditions. 相似文献
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《Journal of heterocyclic chemistry》2017,54(2):1161-1166
An efficient synthesis of β‐lactams has been expediently accomplished. These β‐lactams were synthesized by the Staudinger reaction of several substituted imines with various carboxylic acids using activated DMSO at ambient temperature. The imines and substituted acetic acids contain alkyl, aryl, hetero aryl, polycyclic, and 3‐electron‐withdrawing group underwent [2 + 2] ketene‐imine cycloaddition reaction smoothly to obtain the desired β‐lactams in good to excellent yields. This method is cheap, simple, convenient, and efficient, and the products are easily isolated. 相似文献
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Asymmetric Construction of Pyrrolidines Bearing a Trifluoromethylated Quaternary Stereogenic Center via CuI‐Catalyzed 1,3‐Dipolar Cycloaddition of Azomethine Ylides with β‐CF3‐β,β‐Disubstituted Nitroalkenes 下载免费PDF全文
Dr. Li‐Wei Tang Bao‐Jing Zhao Li Dai Man Zhang Prof. Dr. Zhi‐Ming Zhou 《化学:亚洲杂志》2016,11(17):2470-2477
A direct and convenient method has been developed for the synthesis of optically active pyrrolidines bearing a quaternary stereogenic center containing a CF3 group at the C‐3 position of the pyrrolidine ring. The synthesis system, CuI/Si‐FOXAP‐catalyzed exo‐selective 1,3‐dipolar cycloaddition of azomethine ylides with β‐CF3‐β,β‐disubstituted nitroalkenes, provides pyrrolidines with high diastereoselectivities (up to >98:2 d.r.) and excellent enantioselectivities (up to >99.9 ee) and performs well for a broad scope of substrates under mild conditions. 相似文献
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Yangxue Liu Sultan Ahmed Xiao‐Yan Qin Hossein Rouh Guanzhao Wu Guigen Li Bo Jiang 《化学:亚洲杂志》2020,15(7):1125-1131
An effective chiral GAP methodology for preparing α‐aminomethyl enaminones through a (R)‐CSA‐catalyzed asymmetric aza‐Baylis‐Hillman reaction is reported. Excellent yields and high diastereoselectivity could be obtained under mild conditions and convenient GAP techniques. The confirmations of the absolute configuration of N‐phosphonyl imine and chiral enaminone by X‐ray diffraction provides an explicit explanation of the chirality mechanism for GAP chemistry. 相似文献
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A racemic cis/trans mixture of 5‐hexyl‐4‐methyl‐γ‐butyrolactone was easily synthesized from 1‐iodoheptane in four steps with inexpensive and readily available reagents. Our new synthesis method can be potentially employed for mass production of the 4‐methyl‐5‐hexyl‐γ‐butyrolactone as well as other poly‐alkyl substituted γ‐butyrolactones. 相似文献
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本文报道一种安全,环境有好,经济实用的合成b氨基酸衍生物的新方法。利用α,β不饱和化合物和脂肪族胺,通过无溶剂、无催化的aza-Michael加成反应,高产率的合成b氨基酸衍生物。 相似文献