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Recently the hydrogen-bond activated reactions have attracted much attention.1 Takemoto2 reported a highly enantioselective Michael addition of manolate to nitroolefins catalyzed by a bifunctional organocatalyst with tertiary amine and thiourea moiety. As we known,stereoselective conjugate additions of thiols are interesting due to the standpoint of biological and synthetic importance, however, only very limited good results have been obtained except for the works of Shibasaki3, Kanemasa4 and Deng5 et al.In this letter, we report an efficient catalytic asymmetric Michael reactions of thiols to a,a-unsaturated carbonyl compounds promoted by bifunctional organocatalysts. A series of organocatalysts with chiral amine and thiourea structures were designed and synthesized and have been successfully applied in the conjugated additions of thiols to a,a-unsaturated imides and enones.The reactions got quantitative yields and the ee values were up to 84%. It is noteworthy that the a-asymmetric protonation (up to 43% ee) also could be achieved.The Michael addition between aromatic thiols and a,a-unsaturated carbonyl compounds isdescribed as follows:Works to further increase the enantioselectivity is under investigation in our laboratory. 相似文献
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手性助剂控制的不对称反应是不对称合成的主要方法之一.采用不同空间位阻Evans手性助剂对呋喃基丙烯酸进行立体选择性控制,通过不同空间位阻的格氏试剂对Michael受体1进行不对称1,4-Michael加成反应研究,合成了一系列新的Michael加成产物2a~2h.研究结果表明手性助剂及格氏试剂的空间位阻是影响反应立体选择性的主要因素.当手性助剂及格氏试剂的取代基为芳基时,产物的de值都大于95%,而取代基为烷基、苄基及脂环基时,产物的de值则低于70%. 相似文献
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Highly Enantioselective Tandem Michael Addition of Tryptamine‐Derived Oxindoles to Alkynones: Concise Synthesis of Strychnos Alkaloids 下载免费PDF全文
Weigang He Jiadong Hu Pengyan Wang Le Chen Kai Ji Siyu Yang Yin Li Zhilong Xie Prof. Dr. Weiqing Xie 《Angewandte Chemie (International ed. in English)》2018,57(14):3806-3809
A highly enantioselective tandem Michael addition of tryptamine‐derived oxindoles to alkynones was developed by taking advantage of a chiral N,N′‐dioxide Sc(OTf)3 catalyst. The reaction enables the facile preparation of enantioenriched spiro[pyrrolidine‐3,3′‐oxindole] compounds, which provides a novel strategy for the synthesis of monoterpenoid indole alkaloids. As a demonstration, the asymmetric synthesis of strychnos alkaloids [(?)‐tubifoline, (?)‐tubifolidine, (?)‐dehydrotubifoline] was achieved in 10–11 steps. 相似文献
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Phosphine‐Catalyzed Enantioselective γ‐Addition of 3‐Substituted Oxindoles to 2,3‐Butadienoates and 2‐Butynoates: Use of Prochiral Nucleophiles 下载免费PDF全文
Tianli Wang Weijun Yao Fangrui Zhong Guo Hao Pang Prof. Dr. Yixin Lu 《Angewandte Chemie (International ed. in English)》2014,53(11):2964-2968
The first phosphine‐catalyzed enantioselective γ‐addition with prochiral nucleophiles and 2,3‐butadienoates as the reaction partners has been developed. Both 3‐alkyl‐ and 3‐aryl‐substituted oxindoles could be employed in this process, which is catalyzed by a chiral phosphine that is derived from an amino acid, thus affording oxindoles that bear an all‐carbon quaternary center at the 3‐position in high yields and excellent enantioselectivity. The synthetic value of these γ‐addition products was demonstrated by the formal total synthesis of two natural products and by the preparation of biologically relevant molecules and structural scaffolds. 相似文献
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Highly E‐Selective and Enantioselective Michael Addition to Electron‐Deficient Internal Alkynes Under Chiral Iminophosphorane Catalysis 下载免费PDF全文
Dr. Daisuke Uraguchi Kohei Yamada Prof. Dr. Takashi Ooi 《Angewandte Chemie (International ed. in English)》2015,54(34):9954-9957
A highly E‐selective and enantioselective conjugate addition of 2‐benzyloxythiazol‐5(4H)‐ones to β‐substituted alkynyl N‐acyl pyrazoles is achieved under the catalysis of a P‐spiro chiral iminophosphorane. Simultaneous control of the newly generated central chirality and olefin geometry is possible with a wide array of the alkynyl Michael acceptors possessing different aromatic and aliphatic β‐substituents, as well as the various α‐amino acid‐derived thiazolone nucleophiles. This protocol provides access to structurally diverse, optically active α‐amino acids bearing a geometrically defined trisubstituted olefinic component at the α‐position. 相似文献
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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
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Palladacycle Catalyzed Asymmetric PH Addition of Diarylphosphines to N‐Enoyl Phthalimides 下载免费PDF全文
Renta Jonathan Chew Dr. Yunpeng Lu Yu‐Xiang Jia Bin‐Bin Li Esther Hui Yen Wong Rosanne Goh Dr. Yongxin Li Dr. Yinhua Huang Dr. Sumod Appukuttan Pullarkat Prof. Dr. Pak‐Hing Leung 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(44):14514-14517
The first asymmetric phospha‐Michael addition of diarylphosphines to N‐enoyl phthalimides has been developed in the presence of a chiral palladacycle catalyst. A library of free chiral tertiary phosphine adducts were directly obtained with excellent yields and enantioselectivities. Products can be subsequently functionalized to afford β‐phosphinoamides, the direct preparation of which from cinnamides has been notoriously challenging. 相似文献
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An efficient enantioselective cascade sulfa‐Michael/Michael addition reaction of trans‐3‐(2‐mercaptophenyl)‐2‐propenoic acid ethyl ester with nitroalkenes catalyzed by a chiral squaramide catalyst was disclosed. This cascade reaction afforded thiochroman derivatives with three contiguous stereocenters in high yields (up to 94%), excellent diastereoselectivities (up to >25:1 dr) and enantioselectivities (up to 99% ee). 相似文献
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Abhisek Midya Laxman Devidas Khalse Prof. Prasanta Ghorai 《European journal of organic chemistry》2023,26(14):e202201409
Disclosed here an amine-catalyzed reductive aldol-condensation followed by an intramolecular reductive Michael-addition cascade employing Hantzsch ester as hydride source to a keto-bis-enone to provide enantio- and diastereoselective benzannulated diquinanes having three consecutive stereocenters, one of which is an all-carbon quaternary formyl stereocenter. Interestingly, on changing a tether connecting the ketone and an enone moiety from an aliphatic to an aromatic, a change in reactivity is observed. In this case, instead of the above-mentioned reductive aldol condensation, an asymmetric aldol reaction occurs, followed by an iminium/enamine isomerization and, finally diastereoselective Michael addition reaction occurs. As a result, a bis-benzannulated diquinane is obtained with vicinal congested quaternary chiral centers. 相似文献
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研究报道了Au(I)/手性叔胺串联催化实现的一锅法不对称反应,实现从重氮氧化吲哚和氟代烯醇硅醚出发构建螺环季碳氧化吲哚.反应的第一步是3.0 mol% IPrAuBF4催化的重氮氧化吲哚与单氟烯醇硅醚的交叉偶联反应,现场产生N-Ac保护的3-烯基氧化吲哚在手性叔胺-四方酸C1的催化下与N-Ts邻氨基查尔酮再发生不对称Michael/Michael反应,以中等到良好的产率以及对映选择性,>20:1的非对映选择性得到螺环季碳氧化吲哚.反应的关键一步是Au(I)催化的给体-受体类重氮化合物与三取代单氟烯醇硅醚的成烯化反应,高效构建三取代烯烃. 相似文献