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1.
Kengo Masuda Masaki Koshimizu Dr. Masanori Nagatomo Prof. Dr. Masayuki Inoue 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):230-236
(+)‐Ryanodine ( 1 ) is the ester derivative of 1H‐pyrrole‐2‐carboxylic acid and the complex terpenoid (+)‐ryanodol ( 2 ), which possesses eleven contiguous stereogenic centers on the ABCDE‐ring system. Compound 1 is known to be a potent modulator of intracellular calcium release channels, whereas the activity of 2 is significantly weaker. To chemically construct 1 , the multiple oxygen functional groups must be installed on the fused pentacycle in stereoselective fashions and the extremely hindered C3‐hydroxy group must be acylated in a site‐selective manner. First, the total synthesis of 2 was accomplished by introducing the five stereocenters from the previously prepared enantiopure ABDE‐ring 7 . Stereoselective construction of the C3‐secondary, C2‐ and C6‐tertiary alcohols was achieved by three nucleophilic reactions. The C9‐ and C10‐trisubstituted carbon centers were regio‐ and stereoselectively introduced by hydroboration/oxidation of the six‐membered C‐ring, which was formed by the ring‐closing metathesis reaction. Direct esterification of the C3‐alcohol with pyrrole‐2‐carboxylic acid proved unsuccessful; therefore, we developed a new, two‐step protocol for attachment of the pyrrole moiety. The C3‐hydroxy group was first converted into the less sterically cumbersome glycine ester, which was then transformed into the pyrrole ring through condensation with 1,3‐bis(dimethylamino)allylium tetrafluoroborate. This procedure resulted in the first total synthesis of 1 . 相似文献
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Decarbonylative Radical Coupling of α‐Aminoacyl Tellurides: Single‐Step Preparation of γ‐Amino and α,β‐Diamino Acids and Rapid Synthesis of Gabapentin and Manzacidin A 下载免费PDF全文
Dr. Masanori Nagatomo Hayato Nishiyama Haruka Fujino Prof. Dr. Masayuki Inoue 《Angewandte Chemie (International ed. in English)》2015,54(5):1537-1541
A new radical‐based coupling method has been developed for the single‐step generation of various γ‐amino acids and α,β‐diamino acids from α‐aminoacyl tellurides. Upon activation by Et3B and O2 at ambient temperature, α‐aminoacyl tellurides were readily converted into α‐amino carbon radicals through facile decarbonylation, which then reacted intermolecularly with acrylates or glyoxylic oxime ethers. This mild and powerful method was effectively incorporated into expeditious synthetic routes to the pharmaceutical agent gabapentin and the natural product (?)‐manzacidin A. 相似文献
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Gold(I) as an Artificial Cyclase: Short Stereodivergent Syntheses of (−)‐Epiglobulol and (−)‐4β,7α‐ and (−)‐4α,7α‐Aromadendranediols 下载免费PDF全文
Dr. Javier Carreras Madeleine Livendahl Dr. Paul R. McGonigal Prof. Antonio M. Echavarren 《Angewandte Chemie (International ed. in English)》2014,53(19):4896-4899
Three natural aromadendrane sesquiterpenes, (?)‐epiglobulol, (?)‐4β,7α‐aromadendranediol, and (?)‐4α,7α‐aromadendranediol, have been synthesized in only seven steps in 12, 15, and 17 % overall yields, respectively, from (E,E)‐farnesol by a stereodivergent gold(I)‐catalyzed cascade reaction which forms the tricyclic aromadendrane core in a single step. These are the shortest total syntheses of these natural compounds. 相似文献
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Nobuhiro Shionozaki Naoki Iwamura Ryo Tanaka Prof. Kimiko Makino Prof. Hiromi Uchiro 《化学:亚洲杂志》2013,8(6):1243-1252
The first total synthesis of diaporthichalasin has been successfully achieved and complete structure elucidation, including the absolute configuration, was also accomplished. The intramolecular Diels–Alder (IMDA) reaction between the diene side chain on the decalin skeleton and α,β‐unsaturated γ‐hydroxy‐γ‐lactam in aqueous media was effectively employed as the key step. From this synthetic study, we found that α,β‐unsaturated γ‐hydroxy‐γ‐lactam is an essential precursor for the construction of the diaporthichalasin‐type pentacyclic skeleton. This important finding strongly suggests that this route is involved in the biosynthetic pathway for diaporthichalasin. 相似文献
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Danny Q. Thach Zachary G. Brill Huck K. Grover Kenneth V. Esguerra Jordan K. Thompson Thomas J. Maimone 《Angewandte Chemie (International ed. in English)》2020,59(4):1532-1536
The ophiobolin sesterterpenes are notable plant pathogens which have recently elicited significant chemical and biological attention because of their intriguing carbogenic frameworks, reactive functionalities, and emerging anticancer profiles. Reported herein is a total synthesis of (+)‐6‐epi‐ophiobolin A in 14 steps, a task which addresses construction of the synthetically challenging spirocyclic tetrahydrofuran motif as well as several other key stereochemical problems. This work demonstrates a streamlined synthetic platform to complex ophiobolins leveraging disparate termination modes of a radical polycyclization cascade for divergent elaboration and functionalization. 相似文献
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Cedric L. Hugelshofer Dr. Thomas Magauer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):15125-15136
We present a full account of the development of a strategy that culminated in the first total syntheses of the unique oxetane‐containing natural product (+)‐dictyoxetane and the macrocyclic diterpene (+)‐dolabellane V. Our retrosynthetic planning was guided by both classical and nonconventional strategies to construct the oxetane, which is embedded in an unprecedented 2,7‐dioxatricyclo[4.2.1.03,8]nonane ring system. Highlights of the successful approach include highly diastereoselective carbonyl addition reactions to assemble the full carbon skeleton, a Grob fragmentation to construct the 11‐membered macrocycle of (+)‐dolabellane V, and a bioinspired 4‐exo‐tet, 5‐exo‐trig cyclization sequence to form the complex dioxatricyclic framework of (+)‐dictyoxetane. Furthermore, an unprecedented strain‐releasing type I dyotropic rearrangement of an epoxide‐oxetane substrate was developed. 相似文献
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Dr. Zhiqiang Ma Dr. Ruining Li Zhen Zhang Cheng Tao Dr. Bin Cheng Dr. Yun Li Dr. Huifei Wang Prof. Dr. Hongbin Zhai 《Angewandte Chemie (International ed. in English)》2016,55(38):11638-11641
Described herein is the first asymmetric total synthesis of (+)‐harringtonolide, a natural diterpenoid with an unusual tropone imbedded in a cagelike framework. The key transformations include an intramolecular Diels–Alder reaction and a rhodium‐complex‐catalyzed intramolecular [3+2] cycloaddition to install the tetracyclic core as well as a highly efficient tropone formation. 相似文献
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Chuan He Jun Xuan Peirong Rao Pei‐Pei Xie Xin Hong Xufeng Lin Hanfeng Ding 《Angewandte Chemie (International ed. in English)》2019,58(15):5100-5104
A concise and divergent approach for the total syntheses of four cembrane diterpenoids, namely (+)‐sarcophytin, (+)‐chatancin, (?)‐3‐oxochatancin, and (?)‐pavidolide B, has been developed, and it also led to the structural revision of (?)‐isosarcophytin. The key steps of the strategy feature a double Mukaiyama Michael addition/elimination, a Helquist annulation, two substrate‐controlled facial‐selective hydrations, and a pinacol rearrangement. The described syntheses not only achieved these natural products in an efficient manner, but also provided insight into the biosynthetic relationship between the two different skeletons. 相似文献
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Protecting‐Group‐Free Enantioselective Synthesis of (−)‐Pallavicinin and (+)‐Neopallavicinin 下载免费PDF全文
Bin Huang Lei Guo Prof. Yanxing Jia 《Angewandte Chemie (International ed. in English)》2015,54(46):13599-13603
The first enantioselective synthesis of (?)‐pallavicinin and (+)‐neopallavicinin has been achieved in 15 steps. The described synthesis avoids protecting‐group manipulations by synthesis designs predicated on highly chemo‐ and stereoselective transformations. Highlights of the synthesis include a palladium‐catalyzed enantioselective decarboxylative allylation to form the chiral all‐carbon quaternary stereocenter, a palladium‐catalyzed oxidative cyclization to assemble the [3.2.1]‐bicyclic moiety, and an unprecedented LiBHEt3‐induced fragmentation/protonation of an α‐hydroxy epoxide to form the α‐furan ketone with the desired configuration. 相似文献
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Arun K. Ghosh Prof. Dr. Kai Xi 《Angewandte Chemie (International ed. in English)》2009,48(29):5372-5375
Quick access : A concise and efficient formal synthesis of platencin has been accomplished in nine steps from a commercially available starting material. The synthesis utilized only one protecting group. The base‐catalyzed Michael cyclization of precursor 1 afforded the key diketone 2 , which was converted into the desired core structure 4 via the radical intermediate 3 .
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Zhuliang Zhong Gaoyuan Zhao Dengyu Xu Baobiao Dong Dengpeng Song Dr. Xingang Xie Prof. Dr. Xuegong She 《化学:亚洲杂志》2016,11(10):1542-1547
The first bioinspired total syntheses of (?) kravanhins A and C were accomplished from a labdane diterpenoid derivative. The key reactions involve a photooxidation and a one‐pot sequential aldol cyclization and lactonization, which provide a new plausible biosynthetic pathway for the kravanhins and other symbiotic members. 相似文献
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Convergent Assembly of the Tetracyclic Meroterpenoid (−)‐Cyclosmenospongine by a Non‐Biomimetic Polyene Cyclization 下载免费PDF全文
M. Sc. Klaus Speck M. Sc. Raphael Wildermuth Dr. Thomas Magauer 《Angewandte Chemie (International ed. in English)》2016,55(45):14131-14135
The cationic cyclization of polyenes constitutes a powerful and elegant transformation, which has been utilized by nature's biosynthetic machinery for the construction of complex polycyclic terpenoids. Previous studies by chemists to mimic this cyclization in the laboratory were limited to different modes of activation using biosynthetic‐like precursors, which accommodate only simple methyl‐derived substituents. Here we describe the development of an unprecedented and highly efficient polyene cyclization of an aryl enol ether containing substrate. The cyclization was shown to proceed in a stepwise manner to generate three rings and three consecutive stereocenters, two of which are tetrasubstituted, in a single flask. The developed transformation is of great synthetic value and has enabled the convergent assembly of the tetracyclic meroterpenoid (?)‐cyclosmenospongine. 相似文献
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Saiyong Pan Beiling Gao Jialei Hu Jun Xuan Hujun Xie Prof. Dr. Hanfeng Ding 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(3):959-970
The first enantioselective total synthesis of (+)‐steenkrotin A has been achieved in 18 steps and 4.2 % overall yield. The key features of the strategy entail a Rh‐catalyzed O?H bond insertion followed by an intramolecular carbonyl‐ene reaction, two sequential SmI2‐mediated Ueno–Stork and ketyl–olefin cyclizations, and a cascade intramolecular aldol condensation/vinylogous retro‐aldol/aldol process with inversion of the relative configuration at the C7 position. The absolute configuration of (+)‐steenkrotin A was determined based on the stepwise construction of the stereocenters during the total synthesis. 相似文献
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Catalytic Asymmetric Assembly of Octahydroindolones: Divergent Synthesis of Lycorine‐type Amaryllidaceae Alkaloids (+)‐α‐Lycorane and (+)‐Lycorine 下载免费PDF全文
Zhongwen Sun Mingtao Zhou Xiang Li Xueling Meng Fangzhi Peng Prof. Hongbin Zhang Prof. Zhihui Shao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(20):6112-6119
We report the first catalytic asymmetric approach to octahydroindolones and a divergent enantioselective synthesis of perhydroindole alkaloids, as exemplified by lycorine‐type Amaryllidaceae alkaloids (+)‐α‐lycorane and (+)‐lycorine, from a common intermediate by using a highly concise route. The assembly of octahydroindolones employs a catalytic enantioselective 1,4‐conjugate addition of nitro dienynes, followed by a TsOH‐catalyzed cascade synthesis of highly functionalized enones, and a diastereoselective intramolecular Michael addition. 相似文献
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A General Entry to Antifeedant Sesterterpenoids: Total Synthesis of (+)‐Norleucosceptroid A, (−)‐Norleucosceptroid B,and (−)‐Leucosceptroid K 下载免费PDF全文
M. Sc. Cedric L. Hugelshofer Dr. Thomas Magauer 《Angewandte Chemie (International ed. in English)》2014,53(42):11351-11355
The first asymmetric total synthesis of the antifeedant terpenoids (+)‐norleucosceptroid A, (?)‐norleucosceptroid B, and (?)‐leucosceptroid K has been accomplished. This highly concise synthetic route was guided by our efforts to develop a platform for the collective synthesis of a whole family of antifeedant natural products. The synthesis features a Hauser–Kraus‐type annulation followed by an unprecedented, highly efficient intramolecular dilactol aldol‐type condensation reaction to produce the 5,6,5 skeleton. The developed synthetic route proceeds for norleucosceptroid A and B in 16 steps (longest linear sequence) from known compounds. 相似文献