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1.
Hugo Quintela‐Varela Cooper S. Jamieson Qianzhen Shao K. N. Houk Dirk Trauner 《Angewandte Chemie (International ed. in English)》2020,59(13):5263-5267
The combination of electrocyclizations and cycloadditions accounts for the formation of a range of fascinating natural products. Cascades consisting of 8π electrocyclizations followed by a 6π electrocyclization and a cycloaddition are relatively common. We now report the synthesis of the tetramic acid PF‐1018 through an 8π electrocyclization, the product of which is immediately intercepted by a Diels–Alder cycloaddition. The success of this pericyclic cascade was critically dependent on the substitution pattern of the starting polyene and could be rationalized through DFT calculations. The completion of the synthesis required the instalment of a trisubstituted double bond by radical deoxygenation. An unexpected side product formed through 4‐exo‐trig radical cyclization could be recycled through an unprecedented triflation/fragmentation. 相似文献
2.
Cedric L. Hugelshofer Thomas Magauer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(42):11533-11537
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
3.
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
4.
Suckchang Hong Myunggi Jung Yohan Park Min Woo Ha Cheonhyoung Park Dr. Myungmo Lee Prof. Dr. Hyeung‐geun Park 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(29):9599-9605
A new efficient and concise enantioselective synthetic method for (?)‐horsfiline is reported. (?)‐Horsfiline could be obtained from diphenylmethyl tert‐butyl malonate in 9 steps (32 %,>99 % ee) by using the enantioselective phase‐transfer catalytic allylation (91 % ee) as the key step. This approach can be applied as a practical route for the large‐scale synthesis of spirooxindole natural products, which enables a systematic investigation of their biological activity to be performed. 相似文献
5.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14855-14858
One of a number of intriguing new alkaloids isolated from the Leucetta sp. sponge in 2004, spiroleucettadine displayed unique structural features on a restricted scaffold: a trans ‐fused 5,5‐bicyclic ring system together with an amino hemiketal moiety. Attempts to synthesize the initially proposed structure failed, raising questions as to its veracity, and structure revision ensued in 2008; no successful synthetic approach has been reported to date. Herein, we describe the enantiospecific total synthesis of (−)‐spiroleucettadine by a highly efficient biomimetic approach starting from l ‐tyrosine. One of two key hypervalent‐iodine‐mediated oxidation reactions forged the spirocyclic center, and the other enabled the installation of the methylamine side chain in the penultimate step. Our approach provides synthetic access to a new class of spiroannulated natural products and will enable future studies of the structure–biological‐activity relationships of these antibacterial compounds. 相似文献
6.
Christian Kesenheimer Dr. Aris Kalogerakis Dr. Anja Meißner Dr. Ulrich Groth Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(29):8805-8821
A cobalt(I)‐mediated convergent and asymmetric total synthesis of angucyclinones with an aromatic B ring has been developed. In the course of our research, we synthesized three naturally occurring anguclinone derivatives, namely, (+)‐rubiginone B2 ( 1 ), (?)‐8‐O‐methyltetrangomycin ( 2 ), and (?)‐tetrangomycin ( 3 ). By combining 3‐hydroxybenzoic acid, 3‐methoxybenzoic acid, citronellal, and geraniol as starting materials in a convergent way, we were able to synthesize chiral triyne chains, which were cyclized with [CpCo(C2H4)2] (Cp=cyclopentadienyl) by means of an intramolecular [2+2+2] cycloaddition to their corresponding tetrahydrobenzo[a]anthracenes. Successive oxidation and deprotection steps led to the above‐mentioned natural products 1 – 3 . 相似文献
7.
A detailed account of the enantioselective total synthesis of (?)‐lasonolide A is described. Our initial synthetic route to the top tetrahydropyran ring involved Evans asymmetric alkylation as the key step. Initially, we relied on the diastereoselective alkylation of an α‐alkoxyacetimide derivative containing an α′ stereogenic center and investigated such an asymmetric alkylation reaction. Although alkylation proceeded in good yield, the lack of diastereoselectivity prompted us to explore alternative routes. Our subsequent successful synthetic strategies involved highly diastereoselective cycloaddition routes to both tetrahydropyran rings of lasonolide A. The top tetrahydropyran ring was constructed stereoselectively by an intramolecular 1,3‐dipolar cycloaddition reaction. The overall process constructed a bicyclic isoxazoline, which was later unravelled to a functionalized tetrahydropyran ring as well as a quaternary stereocenter present in the molecule. The lower tetrahydropyran ring was assembled by a Jacobsen catalytic asymmetric hetero‐Diels–Alder reaction as the key step. The synthesis also features a Lewis acid catalyzed epoxide opening to form a substituted ether stereoselectively. 相似文献
8.
Mujahid Mohammad Venkaiah Chintalapudi Jeffrey M. Carney Steven J. Mansfield Pollyanna Sanderson Kirsten E. Christensen Edward A. Anderson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18345-18349
A highly convergent strategy for the synthesis of the natural product (?)‐rubriflordilactone B, and the proposed structure of (?)‐pseudo‐rubriflordilactone B, is described. Late stage coupling of diynes containing the respective natural product FG rings with a common AB ring aldehyde precedes rhodium‐catalyzed [2+2+2] alkyne cyclotrimerization to form the natural product skeleton, with the syntheses completed in just one further operation. This work resolves the uncertainty surrounding the identity of pseudo‐rubriflordilactone B and provides a robust platform for further synthetic and biological investigations. 相似文献
9.
Naifeng Hu Changming Dong Cuifang Zhang Guangxin Liang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6731-6734
The concise total syntheses of (?)‐indoxamycins A and B is reported. The chemistry features a seven‐step preparation of a highly congested [5.5.6] tricyclic advanced common intermediate from a readily available R‐carvone derivative. Key steps involve a Pauson–Khand reaction for the rapid construction of a basic scaffold bearing a quaternary carbon, a copper‐catalyzed Michael addition for the introduction of another adjacent all‐carbon quaternary stereocenter, and a tandem retro‐oxa‐Michael addition/1,2‐addition/oxa‐Michael addition for the installation of a trisubstituted olefin side chain. This synthetic strategy allows for easy access to both enantiomers of this family of natural products and their analogues from cost‐effective starting material through straightforward chemical transformations. 相似文献
10.
Yuye Chen Jingping Hu Lian‐Dong Guo Weihe Zhong Chengqing Ning Jing Xu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(22):7468-7472
The daphniphyllum alkaloids are a structurally fascinating and remarkably diverse family of natural products. General strategies for the chemical synthesis of their challenging architectures are highly desirable for efficiently accessing these intriguing alkaloids and addressing their pharmaceutical potential. Herein, a concise strategy designed to provide general and diversifiable access to various daphniphyllum alkaloids is described and utilized in the asymmetric synthesis of (?)‐himalensine A, which was accomplished in 14 steps. Key features of this strategy include a Cu‐catalyzed nitrile hydration, a Heck reaction to construct the challenging 2‐azabicyclo[3.3.1]nonane motif, a Meinwald rearrangement reaction, six, pot‐economic reactions, and the minimal use of protecting groups, which significantly improved the overall synthetic efficiency. 相似文献
11.
Divergent Total Syntheses of Enmein‐Type Natural Products: (−)‐Enmein, (−)‐Isodocarpin,and (−)‐Sculponin R 下载免费PDF全文
Saiyong Pan Sicong Chen Guangbin Dong 《Angewandte Chemie (International ed. in English)》2018,57(21):6333-6336
Divergent total syntheses of the enmein‐type natural products (?)‐enmein, (?)‐isodocarpin, and (?)‐sculponin R have been achieved in a concise fashion. Key features of the strategy include 1) an efficient early‐stage cage formation to control succeeding diastereoselectivity, 2) a one‐pot acylation/akylation/lactonization to construct the C‐ring and C8 quarternary center, 3) a reductive alkenylation approach to construct the enmain D/E rings and 4) a flexible route to allow divergent syntheses of three natural products. 相似文献
12.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(21):6441-6444
Divergent total syntheses of the enmein‐type natural products (−)‐enmein, (−)‐isodocarpin, and (−)‐sculponin R have been achieved in a concise fashion. Key features of the strategy include 1) an efficient early‐stage cage formation to control succeeding diastereoselectivity, 2) a one‐pot acylation/akylation/lactonization to construct the C‐ring and C8 quarternary center, 3) a reductive alkenylation approach to construct the enmain D/E rings and 4) a flexible route to allow divergent syntheses of three natural products. 相似文献
13.
Synthesis of (−)‐Hebelophyllene E: An Entry to Geminal Dimethyl‐Cyclobutanes by [2+2] Cycloaddition of Alkenes and Allenoates 下载免费PDF全文
Dr. Johannes M. Wiest Dr. Michael L. Conner Prof. M. Kevin Brown 《Angewandte Chemie (International ed. in English)》2018,57(17):4647-4651
The first synthesis of hebelophyllene E is presented, along with assignment of its previously unknown relative configuration through synthesis of epi‐ent‐hebelophyllene E. Development of a catalytic enantioselective [2+2] cycloaddition of alkenes and allenoates provides access to the required chiral geminal dimethylcyclobutanes. Key to its success is the identification of a novel oxazaborolidine catalyst which promotes the cycloaddition in high enantioselectivities with good functional‐group tolerance (9 examples, up to 97:3 e.r.). Thus, a late‐stage cycloaddition using a fully functionalized alkene, followed by a diastereoselective reduction allows a concise entry to this class of natural products. 相似文献
14.
Hong‐Xiu Huang Shuai‐Jiang Jin Jin Gong Dr. Dan Zhang Dr. Hao Song Prof. Yong Qin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(38):13284-13290
The bioactive Kopsia alkaloids lundurines A–D are the only natural products known to contain indolylcyclopropane. Achieving their syntheses can provide important insights into their biogenesis, as well as novel synthetic routes for complex natural products. Asymmetric total synthesis of (?)‐lundurine A has previously been achieved through a Simmons–Smith cyclopropanation strategy. Here, the total synthesis of (?)‐lundurine A was carried out using a metal‐catalyzed diazo cyclopropanation strategy. In order to avoid a carbene C?H insertion side reaction during cyclopropanation of α‐diazo‐ carboxylates or cyanides, a one‐pot, copper‐catalyzed Bamford–Stevens diazotization/diazo decomposition/cyclopropanation cascade was developed, involving hydrazone. This approach simultaneously generates the C/D/E ring system and the two chiral quaternary centers at C2 and C7. 相似文献
15.
《化学:亚洲杂志》2017,12(12):1309-1313
An asymmetric route to (−)‐α‐lycorane and (−)‐zephyranthine, and a formal total synthesis of (+)‐clivonine were achieved. A pivotal intermediate, which serves as a potent precursor for the divergent syntheses of these natural products, was accessed by a diastereoselective Pd‐catalyzed cinnamylation of an N ‐tert ‐butanesulfinyl imine. 相似文献
16.
Prof. Dr. Takayuki Doi Dr. Yoshitaka Numajiri Prof. Dr. Takashi Takahashi Dr. Motoki Takagi Dr. Kazuo Shin‐ya 《化学:亚洲杂志》2011,6(1):180-188
Two approaches for the solid‐phase total synthesis of apratoxin A and its derivatives were accomplished. In synthetic route A, the peptide was prepared by the sequential coupling of the corresponding amino acids on trityl chloride SynPhase Lanterns. After cleavage from the polymer‐support, macrolactamization of 10 , followed by thiazoline formation, provided apratoxin A. This approach, however, resulted in low yield because the chemoselectivity was not sufficient for the formation of the thiazoline ring though its analogue 33 was obtained. However, in synthetic route B, a cyclization precursor was prepared by solid‐phase peptide synthesis by using amino acids 13 – 15 and 18 . The final macrolactamization was performed in solution to provide apratoxin A in high overall yield. This method was then successfully applied to the synthesis of apratoxin analogues. The cytotoxic activity of the synthetic derivatives was then evaluated. The epimer 34 was as potent as apratoxin A, and O‐methyl tyrosine can be replaced by 7‐azidoheptyl tyrosine without loss of activity. The 1,3‐dipolar cycloaddition of 38 with phenylacetylene was performed in the presence of a copper catalyst without affecting the thiazoline ring. 相似文献
17.
Xinkan Yang Houqiang Lv Xiaoru Shao Cheng Tao Dr. Huifei Wang Dr. Bin Cheng Dr. Yun Li Jingjing Guo Jing Zhang Prof. Dr. Hongbin Zhai 《Angewandte Chemie (International ed. in English)》2018,57(4):947-951
(?)‐Daphnilongeranin B and (?)‐daphenylline are two hexacyclic Daphniphyllum alkaloids, each containing a complex cagelike backbone. Described herein are the first asymmetric total synthesis of (?)‐daphnilongeranin B and a bioinspired synthesis of (?)‐daphenylline with an unusual E ring embedded in a cagelike framework. The key features include an intermolecular [3+2] cycloaddition, a late‐stage aldol cyclization to install the F ring of daphnilongeranin B, and a bioinspired cationic rearrangement leading to the tetrasubstituted benzene ring of daphenylline. 相似文献
18.
Biomimetic Total Syntheses of (−)‐Leucoridines A and C through the Dimerization of (−)‐Dihydrovalparicine 下载免费PDF全文
Praveen Kokkonda Keaon R. Brown Trevor J. Seguin Dr. Steven E. Wheeler Dr. Shivaiah Vaddypally Dr. Michael J. Zdilla Dr. Rodrigo B. Andrade 《Angewandte Chemie (International ed. in English)》2015,54(43):12632-12635
Concise biomimetic syntheses of the Strychnos‐Strychnos‐type bis‐indole alkaloids (?)‐leucoridine A ( 1 ) and C ( 2 ) were accomplished through the biomimetic dimerization of (?)‐dihydrovalparicine ( 3 ). En route to 3 , the known alkaloids (+)‐geissoschizoline ( 8 ) and (?)‐dehydrogeissoschizoline ( 10 ) were also prepared. DFT calculations were employed to elucidate the mechanism, which favors a stepwise aza‐Michael/spirocyclization sequence over the alternate hetero‐Diels–Alder cycloaddition reaction. 相似文献
19.
Enantioselective Total Syntheses of (−)‐Rhazinilam, (−)‐Leucomidine B,and (+)‐Leuconodine F 下载免费PDF全文
Dylan Dagoneau Dr. Zhengren Xu Dr. Qian Wang Prof. Dr. Jieping Zhu 《Angewandte Chemie (International ed. in English)》2016,55(2):760-763
A divergent total synthesis of three structurally distinct natural products from imine 9 was accomplished through an approach featuring: 1) a Pd‐catalyzed decarboxylative cross‐coupling, and 2) heteroannulation of 9 with bromoacetaldehyde and oxalyl chloride to give tetrahydroindolizine 6 and dioxopyrrole 7 , respectively. The former was converted into (?)‐rhazinilam, while the latter was converted into (?)‐leucomidine B and (+)‐leuconodine F. A substrate‐directed highly diastereoselective reduction of a sterically unbiased double bond by using a homogeneous palladium catalyst was developed. A self‐induced diastereomeric anisochronism (SIDA) phenomenon was observed for leucomidine B. 相似文献
20.
Dylan Dagoneau Zhengren Xu Qian Wang Jieping Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(2):770-773
A divergent total synthesis of three structurally distinct natural products from imine 9 was accomplished through an approach featuring: 1) a Pd‐catalyzed decarboxylative cross‐coupling, and 2) heteroannulation of 9 with bromoacetaldehyde and oxalyl chloride to give tetrahydroindolizine 6 and dioxopyrrole 7 , respectively. The former was converted into (−)‐rhazinilam, while the latter was converted into (−)‐leucomidine B and (+)‐leuconodine F. A substrate‐directed highly diastereoselective reduction of a sterically unbiased double bond by using a homogeneous palladium catalyst was developed. A self‐induced diastereomeric anisochronism (SIDA) phenomenon was observed for leucomidine B. 相似文献