共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
Jie Yang Xiao‐Ming Zhang Fu‐Min Zhang Shao‐Hua Wang Yong‐Qiang Tu Zhen Li Xi‐Chao Wang Hong Wang 《Angewandte Chemie (International ed. in English)》2020,59(22):8471-8475
An enantioselective aldehyde α‐alkylation/semipinacol rearrangement was achieved through organo‐SOMO catalysis. The catalytically generated enamine radical cation serves as a carbon radical electrophile that can stereoselectively add to the alkene of an allylic alcohol and initiate ensuing ring‐expansion of cyclopropanol or cyclobutanol. This tandem reaction enables the production of a wide range of nonracemic functionalizable α‐quaternary‐δ‐carbonyl cycloketones in high yields and excellent enantioselectivity from simple aldehydes and allylic alcohols. As a key step, the intramolecular reaction was also successfully applied in the asymmetric total synthesis of (+)‐cerapicol. 相似文献
3.
Total Syntheses of the Tetracyclic Cyclopiane Diterpenes Conidiogenone,Conidiogenol, and Conidiogenone B
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Si‐Hua Hou Prof. Dr. Yong‐Qiang Tu Shuang‐Hu Wang Chao‐Chao Xi Prof. Dr. Fu‐Min Zhang Prof. Dr. Shao‐Hua Wang Yan‐Tao Li Lin Liu 《Angewandte Chemie (International ed. in English)》2016,55(14):4456-4460
Total syntheses of the biologically important and structurally unique tetracyclic diterpenes conidiogenone, conidiogenol, and conidiogenone B of the cyclopiane class are reported. The absolute configuration of naturally occurring conidiogenone B was also corrected. The key step of our strategy involved the highly efficient construction of both ring C and the quaternary carbon center shared by rings A and C through a one‐step regioselective and diastereoselective cycloenlargement in the form of a semipinacol‐type rearrangement. In particular, the desired regioselectivity was made possible by properly adjusting the migratory aptitude of the migrating carbon atom through the introduction of an electron‐donating phenylthio group at this position. 相似文献
4.
Frontispiece: Total Syntheses of the Tetracyclic Cyclopiane Diterpenes Conidiogenone,Conidiogenol, and Conidiogenone B
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Si‐Hua Hou Prof. Dr. Yong‐Qiang Tu Shuang‐Hu Wang Chao‐Chao Xi Prof. Dr. Fu‐Min Zhang Prof. Dr. Shao‐Hua Wang Yan‐Tao Li Lin Liu 《Angewandte Chemie (International ed. in English)》2016,55(14)
5.
Seung‐Mann Paek Dr. Nam‐Jung Kim Dongyun Shin Dr. Jae‐Kyung Jung Prof. Jong‐Wha Jung Dr. Dong‐Jo Chang Dr. Hyunyoung Moon Young‐Ger Suh Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(15):4623-4628
Highly concise asymmetric total syntheses of (+)‐tetrabenazine ( 1 ), a drug for the treatment of chorea associated with Huntington’s disease, and of (+)‐α‐dihydrotetrabenazine ( 2 ), an active metabolite of 1 , have been accomplished. Our synthetic route features a trans‐selective enol etherification, followed by an unprecedented cation‐dependent aza‐Claisen rearrangement to establish the carbon framework and two stereogenic centers of tetrabenazine. The syntheses consist of seven steps (34 % overall yield) for (+)‐ 2 and eight steps (22 % overall yield) for (+)‐ 1 . 相似文献
6.
A Facile Approach to Oximes and Ethers by a Tandem NO+‐Initiated Semipinacol Rearrangement and H‐Elimination
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jia‐Wei Dong Dr. Tongmei Ding Prof. Dr. Shu‐Yu Zhang Prof. Dr. Zhi‐Min Chen Prof. Dr. Yong‐Qiang Tu 《Angewandte Chemie (International ed. in English)》2018,57(40):13192-13196
An efficient oximation method has been developed on the basis of NO+‐initiated semipinacol rearrangement and subsequent proton elimination. The procedure enabled the rapid construction of a series of oximes and oxime ethers with spiro quaternary stereocenters from allylic silyl ethers. Additional features of this reaction include wide substrate tolerance as well as the commercial availability of the safe nitrosation reagent NOBF4. The key N‐heterotricyclic cores of three natural alkaloids, tuberostemoninol B, (+)‐quebrachidine, and an insecticide, were also constructed efficiently by this method. 相似文献
7.
Wei Ye 《Tetrahedron letters》2009,50(51):7156-1290
An efficient synthesis of 6′-isoneplanocin A and 6′ -isohomoneplanocin A is reported. The key steps in the synthesis include an enyne metathesis and a regioselective oxidation. 相似文献
8.
The fully substituted cyclopentenedione core of madindoline A (1) and B (2) as potent and selective inhibitor of IL-6 has been synthesized efficiently. The quaternary carbon center C-2' was constructed on the basis of a newly developed AIEt3-promoted tandem reductive rearrangement of α-hydroxy epoxides. 相似文献
9.
10.
11.
12.
2′,3′-Dideoxy-6′-fluorocarbocyclic nucleosides, analogues of highly bioactive carbovir and abacavir were synthesized. The notable steps were the incorporation of fluoromethylene group by way of silicon-induced Reformatskii-Claisen rearrangement of allyl bromofluoroacetate, the construction of the carbocyclic ring via ring-closing metathesis (RCM) and the introduction of base by Mitsunobu reaction. 相似文献
13.
Gang Liu Tian‐Jun Wu Dr. Yuan‐Ping Ruan Prof. Pei‐Qiang Huang Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(19):5755-5768
The asymmetric total synthesis of natural azasugars (+)‐castanospermine, (+)‐7‐deoxy‐6‐epi‐castanospermine, and synthetic (+)‐1‐epi‐castanospermine has been accomplished in nine to ten steps from a common chiral building block (S)‐ 8 . The method features a powerful chiral relay strategy consisting of a highly diastereoselective vinylogous Mukaiyama‐type reaction with either chiral or achiral aldehydes (≥95 % de; de=diastereomeric excess) and a diastereodivergent reduction of tetramic acids, which allows formation of three continuous stereogenic centers with high diastereoselectivities. The method also provides a flexible access to structural arrays of 5‐(α‐hydroxyalkyl)tetramic acids, such as 17/34 , and 5‐(α‐hydroxyalkyl)‐4‐hydroxyl‐2‐pyrrolidinones, such as 18 and 25/35 a . The method constitutes the first realization of the challenging chiral synthons A and D and thus of the conceptually attractive retrosynthetic analysis shown in Scheme 1 in a highly enantioselective manner. 相似文献
14.
15.
Xiao‐Chun Han Xue‐Yu Xu Xiao‐Lu Li Yong‐Mei Wang Teruo Matsuura Ji‐Ben Meng 《中国化学》2001,19(4):398-403
A new kind of UV stabilizers, 1‐(3′‐(benzotriazol‐2″‐yl)‐4′‐hydroxy‐benzoyl)‐3‐methyl‐5‐pyrazolones (1a‐d), was synthesized with the aim to bind them chemically to certain polymers. The reaction of 1d with substituted benzaldehydes 4 in the molten state at 150°C and in the solid state at room temperature produced the condensation products l‐(3′‐(5″‐chlorobenzotriazol‐2″‐yl)‐4′‐hydroxyl‐5′‐chlorobenzoyl)‐3‐methyl‐4‐arylmethylene‐5‐pyrazolones (2) and 4,4′‐arylmethylene‐bis [1‐(3′‐(5″‐chloro‐benzotriazol‐2″‐yl)‐4′‐hydroxy‐5′‐chloro‐benzoyl)‐3‐methyl‐5‐pyrazolone] s (3), respectively, as the major product. On the other hand, the reaction of 1d with 4 at 50°C in chloroform solution proceeded non‐selectively to give a mixture of 2 and 3. 相似文献
16.
Jhillu Singh Yadav Dandekar Chandrakanth Yerragorla Gopala Rao Kontham Ravindar Basi V. Subba Reddy 《Helvetica chimica acta》2010,93(7):1432-1438
The stereoselective total synthesis of an antiproliferative and antifungal α‐pyrone natural product (6S)‐5,6‐dihydro‐6‐[(2R)‐2‐hydroxy‐6‐phenylhexyl]‐2H‐pyran‐2‐one is described. The key steps involved are the Prins cyclization, Mitsunobu reaction, and ring‐closing metathesis reaction. 相似文献
17.
Metal‐Free Synthetic Approach to 3‐Monosubstituted Unsymmetrical 1,2,4,5‐Tetrazines Useful for Bioorthogonal Reactions
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yangyang Qu François‐Xavier Sauvage Dr. Gilles Clavier Prof. Fabien Miomandre Prof. Pierre Audebert 《Angewandte Chemie (International ed. in English)》2018,57(37):12057-12061
A facile, efficient and metal‐free synthetic approach to 3‐monosubstituted unsymmetrical 1,2,4,5‐tetrazines is presented. Dichloromethane (DCM) is for the first time recognized as a novel reagent in the synthetic chemistry of tetrazines. Using this novel approach 11 3‐aryl/alkyl 1,2,4,5‐tetrazines were prepared in excellent yields (up to 75 %). The mechanism of this new reaction, including the role of DCM in the tetrazine ring formation, has been investigated by 13C labeling of DCM, and is also presented and discussed as well as the photophysical and electrochemical properties. 相似文献
18.
This paper described a concise construction of (-)-EGCG (1f) (with an overall yield of 20% for seven steps based on the starting cinnamyl alcohol derivative 3), featuring asymmetric dihydroxylation (ADH), intra- and inter-molecular Mitsunobu reaction as key steps. Our strategy disclosed herein constitutes a new effective general synthetic approach toward the analogues of (-)-EGCG (1f). 相似文献
19.
20.
Photo‐irradiation of 2‐(5‐methylthiophen‐2‐yl)‐3‐[(naphthalen‐2‐yl)methoxy]‐4H‐chromen‐4‐ones yielded the fascinating angular tetracyclic products via cyclization involving both 2‐thienyl ring and naphthylmethoxy group via 1,4‐biradical generated in the Norrish type‐II process. The stereochemical dispositions of the products were determined by MM2 energy minimized programme and spectroscopic analysis. 相似文献