排序方式: 共有23条查询结果,搜索用时 15 毫秒
11.
A new tunable phosphine‐catalyzed aza‐Michael β‐addition reaction between allenoates and various hydrazones has been developed. These reactions are most‐efficiently promoted by a catalytic amount of phosphine catalysts. These atom‐economical reactions are operationally simple and their corresponding adducts can been achieved in high yields and high selectivity under mild reaction conditions. Further studies revealed that different phosphine catalyst can produce different adducts from the same starting materials. 相似文献
12.
Hai‐Jun Tang Xinggui Zhang Yu‐Feng Zhang Chao Feng 《Angewandte Chemie (International ed. in English)》2020,59(13):5242-5247
A strategically novel synthetic method for the fluoroarylation of allenic ester was developed that enables the expedient construction of a host of β‐fluoroalkyl‐containing cinnamate derivatives. The reaction proceeds through visible‐light‐promoted gold redox catalysis, occurs smoothly under very mild reaction conditions, accommodates a large variety of functional groups, and more importantly allows the incorporation of fluorine and aryl groups with excellent regio‐ and stereoselectivity. The concomitant activation mode for both the allene motif and the hydrogen fluoride is key for the success of the reaction. 相似文献
13.
14.
In contrast with the reported phosphine‐ and DABCO‐catalyzed [3+2] and [2+2] annulation of allenoates with trifluoromethylketone, the [2+2+2] annulation of allenoates and two molecules of trifluoromethylketone was found under the condition of N‐heterocyclic carbene catalysis. 相似文献
15.
《中国化学》2017,35(9):1469-1473
A phosphine‐catalyzed [4 + 2] annulation of α ‐substituted allenoate with exocyclic alkene moiety of oxindoles or indan‐1,3‐diones has been developed. Thus, under the catalysis of PPh3 (20 mol%), a series of spirooxindole‐ or spiroindan‐1,3‐dione‐cyclohexenes have been obtained in moderate to excellent yields and regioselectivity from the annulations of α ‐methyl allenoates with 3‐methyleneoxindoles or 2‐methyleneindan‐1,3‐diones. This method offers an easy access to structurally novel spirocyclohexenes. 相似文献
16.
Transition‐Metal‐Free Coupling of Alkynes with α‐Bromo Carbonyl Compounds: An Efficient Approach towards β,γ‐Alkynoates and Allenoates 下载免费PDF全文
Wenbo Liu Dr. Zhengwang Chen Dr. Lu Li Dr. Haining Wang Prof. Dr. Chao‐Jun Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):5888-5893
A direct transition‐metal‐free coupling between alkynes and α‐bromo carbonyl compounds has been developed with ultraviolet (UV) light in aqueous media. This method represents a facile approach to synthetically useful β,γ‐alkynyl esters and amides stereoselectively from two readily available starting materials. As an example of the synthetic application of the products, the alkynyl esters were readily converted into allenoates. 相似文献
17.
18.
Phosphahelicenes in Asymmetric Organocatalysis: [3+2] Cyclizations of γ‐Substituted Allenes and Electron‐Poor Olefins 下载免费PDF全文
Maxime Gicquel Yang Zhang Paul Aillard Dr. Pascal Retailleau Dr. Arnaud Voituriez Dr. Angela Marinetti 《Angewandte Chemie (International ed. in English)》2015,54(18):5470-5473
The first use of phosphahelicene in enantioselective organocatalysis is reported. New chiral phosphahelicenes have been prepared and enable highly enantioselective [3+2] cyclization reactions between arylidene‐ or alkylidenemalononitriles and γ‐substituted allenoates or cyanoallenes. These reactions afford cyclopentene derivatives in both high yields and diastereoselectivities, with enantiomeric excesses of up to 97 %. 相似文献
19.
2,3-Allenols were prepared conveniently from the reduction reaction of 2,3-allenoates with DIBAL-H(Diisobutylaluminum hydride) in toluene.A dramatic solvent effect was observed for this reaction. 相似文献
20.
Bifunctional‐Phosphine‐Catalyzed Sequential Annulations of Allenoates and Ketimines: Construction of Functionalized Poly‐heterocycle Rings 下载免费PDF全文
Erqing Li Hongxing Jin Penghao Jia Xuelin Dong Prof. You Huang 《Angewandte Chemie (International ed. in English)》2016,55(38):11591-11594
A highly stereoselective sequential annulation reaction between γ‐substituted allenoates and ketimines was reported. By using bifunctional N‐acyl aminophosphine catalysts, poly‐heterocycle rings were obtained with high stereocontrol in good to excellent yields. The desired products have four contiguous stereogenic centers (one quaternary and three tertiary carbon centers), and only one isomer was obtained in all reactions. 相似文献