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Summary. The indolizidinium alkaloid ipalbidinium and the quinolizidinium alkaloid clathryimine B were prepared starting from brominated
2-aminopyridines using two Pd-catalyzed cross-coupling reactions and a Sandmeyer-type diazotation/iodination protocol as the key steps.
Corresponding author. E-mail: Franz.Bracher@cup.uni-muenchen.de
Received August 2, 2002; accepted August 9, 2002 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(13):3757-3761
The asymmetric total syntheses of a group of structurally complex Kopsia alkaloids, (−)‐kopsine, (−)‐isokopsine, (+)‐methyl chanofruticosinate, (−)‐fruticosine, and (−)‐kopsanone, has been achieved. The key strategies for the construction of the molecular complexity in the targets included an asymmetric Tsuji–Trost rearrangement to set the first quaternary carbon center at C20, an intramolecular cyclopropanation by diazo decomposition to install the second and third quaternary carbon centers at C2 and C7, respectively, and a SmI2‐promoted acyloin condensation to assemble the isokopsine core. A radical decarboxylation of an isokopsine‐type intermediate results in a thermodynamic partial rearrangement to give N‐decarbomethoxyisokopsine and N‐decarbomethoxykopsine, two key intermediates for the syntheses of Kopsia alkaloids with different subtype core structures. 相似文献
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Prof. Dr. Barry M. Trost Dr. Maksim Osipov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16318-16343
The communesin alkaloids are a diverse family of Penicillium‐derived alkaloids. Their caged‐polycyclic structure and intriguing biological profiles have made these natural products attractive targets for total synthesis. Similarly, the ascidian‐derived alkaloid, perophoramidine, is structurally related to the communesins and has also become a popular target for total synthesis. This review serves to summarize the many elegant approaches that have been developed to access the communesin alkaloids and perophoramidine. Likewise, strategies to access the communesin ring system are reviewed. 相似文献
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氧化偶联反应作为一种高效、经济的C—C键构建策略,在天然产物的全合成中得到了重要的应用.近年来,马大为课题组通过发展高效的LiHMDS/I2偶联条件,成功实现了四种复杂吲哚生物碱的全合成,在该领域取得了重要的进展.本文就马大为课题组近年在该领域的工作作一亮点评述. 相似文献
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Fumihiko Yoshimura Dr. Minoru Sasaki Dr. Izumi Hattori Kei Komatsu Dr. Mio Sakai Keiji Tanino Prof. Dr. Masaaki Miyashita Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(27):6626-6644
Highly effective : We report herein the first and highly efficient total syntheses of norzoanthamine and zoanthamine in full detail, which involves stereoselective synthesis of the requisite triene for an intramolecular Diels–Alder reaction via three‐component coupling reactions, the intramolecular Diels–Alder reaction, and subsequent crucial bis‐aminoacetalization as the key steps.
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(52):16901-16903
Total syntheses of the monoterpenoid indole alkaloids (±)‐alstoscholarisine B and C were accomplished starting from a readily available indole‐2‐acetic ester and an α,β‐unsaturated N ‐sulfonyllactam. 相似文献
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Total Syntheses and Biological Evaluation of Both Enantiomers of Several Hydroxylated Dimeric Nuphar Alkaloids 下载免费PDF全文
Dr. Alexander Korotkov Hui Li Charles W. Chapman Dr. Haoran Xue Prof. John B. MacMillan Prof. Alan Eastman Prof. Jimmy Wu 《Angewandte Chemie (International ed. in English)》2015,54(36):10604-10607
Herein, we describe the first total syntheses of five members of the dimeric nuphar alkaloids: (+)‐6,6′‐dihydroxythiobinupharidine (+)‐ 1 a , (+)‐6‐hydroxythiobinupharidine (+)‐ 1 b , (?)‐6,6′‐dihydroxythionuphlutine (?)‐ 2 a , (?)‐6,6′‐dihydroxyneothiobinupharidine (?)‐ 3 a , and (+)‐6,6′‐dihydroxyneothionuphlutine (+)‐ 4 a . The latter two have not been found in nature. We have also made each of their enantiomers (?)‐ 1 a – b , (+)‐ 2 a , (+)‐ 3 a , and (?)‐ 4 a . The key step in these syntheses was the dimerization of an α‐aminonitrile (a hydrolytically stable surrogate for its corresponding hemiaminal) with chiral Lewis acid complexes. We have also reassigned the literature structures of (+)‐ 1 a – 1 b —for those instances in which the NMR spectra were obtained in CD3OD—to their corresponding CD3O‐adducts. Our efforts provide for the first time apoptosis data for (?)‐ 3 a , (+)‐ 4 a , and all five non‐natural enantiomers prepared. The data indicate high apoptotic activity regardless of the enantiomer or relative stereochemical configuration at C7 and C7′. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(24):7084-7087
Aurachins A and B are alkaloids having 3‐hydroxyquinoline N‐oxide cores. An efficient method for the synthesis of 3‐hydroxyquinoline N‐oxides was established and is amenable to the total syntheses of aurachins A and B. Alkylation of 1‐(2‐nitrophenyl)butan‐2‐one with farnesyl bromide took place selectively at the benzylic position, and subsequent treatment of the alkylated product with sodium tert‐butoxide in dimethyl sulfoxide gave aurachin B. Alkylation of 1‐(2‐nitrophenyl)butan‐2‐one with an epoxy iodide derived from farnesol was used to access aurachin A. 相似文献
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John A. Enquist Jr. Dr. Scott C. Virgil Prof. Brian M. Stoltz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(36):9957-9969
A concise and versatile approach toward the preparation of the cyanthiwigin family of cyathane natural products is described. By leveraging a unique double asymmetric catalytic alkylation procedure it is possible to quickly establish two of the most critical stereocenters of the cyanthiwigin framework with high levels of selectivity and expediency. The synthetic route additionally employs both a tandem ring‐closing cross‐metathesis reaction, and an aldehyde‐olefin radical cyclization process, in order to rapidly arrive at the tricyclic cyathane core of the cyanthiwigin molecules. From this unifying intermediate, the preparations of cyanthiwigins B, F, and G are attained swiftly and without the need for protecting groups. 相似文献
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Shogo Kamo Kai Yoshioka Kouji Kuramochi Kazunori Tsubaki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(35):10473-10476
Total syntheses of juglorescein and juglocombins A and B are reported. The highly oxygenated 6/6/5/6/6‐fused pentacyclic ring system of these natural products was constructed through a bioinspired dimerization of 1,4‐naphthoquinone. Notably, five new stereogenic centers were constructed in a single step by the dimerization reaction. The epoxide intermediate obtained from the dimerization was successfully converted into juglocombins A and B through photoinduced reduction of the epoxide, dehydration, and conversion of the resultant quinone into a hydroquinone derivative. The same epoxide intermediate was also converted into a dicarboxylic acid, which was transformed into juglorescein through intramolecular lactonization, hydrolysis of the resulting lactone, and removal of the protecting groups. Furthermore, the relative and absolute configurations of juglorescein and juglocombins A and B were determined. 相似文献
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Oxidation products of ajmaline (I), two of its diastereomers isoajmaline (II) sandwicine (III) and their corresponding diacetyl derivatives namely diacetyl ajmaline (IV), diacetyl isoajmaline (V) and diacetyl sandwicine (VI) has been synthesized by their direct reaction with H2 O 2 and characterised by spectroscopic studies. 相似文献