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1.
Total Synthesis of (±)‐Englerin A Using An Intermolecular [3+2] Cycloaddition Reaction of Platinum‐Containing Carbonyl Ylide 下载免费PDF全文
Prof. Dr. Hiroyuki Kusama Aoi Tazawa Dr. Kento Ishida Prof. Dr. Nobuharu Iwasawa 《化学:亚洲杂志》2016,11(1):64-67
Total synthesis of (±)‐Englerin A has been achieved starting from γ,δ‐ynone 5 in 14 steps. The key feature of this synthesis is the highly efficient and stereoselective preparation of 8‐oxabicyclo[3.2.1]octane derivative 6 , a core skeleton of Englerin A, based on an inverse electron‐demand [3+2] cycloaddition reaction of the platinum‐containing carbonyl ylide, which was developed in our laboratory. 相似文献
2.
Linping Liao Dr. Jingjing Zhou Dr. Zhengshuang Xu Prof. Dr. Tao Ye 《Angewandte Chemie (International ed. in English)》2016,55(42):13263-13266
Nannocystin A, a structurally unique 21‐membered macrocyclic depsipeptide with low nanomolar inhibitory activity against elongation factor 1A, was synthesized according to a strategy involving the vinylogous Mukaiyama aldol reaction, Sharpless epoxidation, olefin metathesis, the Mitsunobu reaction, and a palladium‐catalyzed intramolecular Suzuki coupling of a highly complex cyclization substrate. The overall synthesis is efficient and paves the way for preparation of analogues for drug development efforts. 相似文献
3.
Michael Breunig Po Yuan Tanja Gaich 《Angewandte Chemie (International ed. in English)》2020,59(14):5521-5525
We report a concise and versatile total synthesis of the diterpenoid (+)‐norcembrene 5 from simple building blocks. Ring‐closing metathesis and an auxiliary‐directed 1,4‐addition are the key steps of our synthetic route. During the synthesis, an unprecedented, highly oxidized pentacyclic structural motif was established from a furanocembranoid through transannular [4+2] cycloaddition. 相似文献
4.
Concise,Enantioselective, and Versatile Synthesis of (−)‐Englerin A Based on a Platinum‐Catalyzed [4C+3C] Cycloaddition of Allenedienes 下载免费PDF全文
Ronald Nelson Dr. Moisés Gulías Prof. José L. Mascareñas Dr. Fernando López 《Angewandte Chemie (International ed. in English)》2016,55(46):14359-14363
A practical synthesis of (?)‐englerin A was accomplished in 17 steps and 11 % global yield from commercially available achiral precursors. The key step consists of a platinum‐catalyzed [4C+3C] allenediene cycloaddition that directly delivers the trans‐fused guaiane skeleton with complete diastereoselectivity. The high enantioselectivity (99 % ee) stems from an asymmetric ruthenium‐catalyzed transfer hydrogenation of a readily assembled diene–ynone. The synthesis also features a highly stereoselective oxygenation, and a late‐stage cuprate alkylation that enables the preparation of previously inaccessible structural analogues. 相似文献
5.
Benjamin W. Gung Prof. Dr. Derek T. Craft Lauren N. Bailey Kristin Kirschbaum Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):639-644
Macrocyclic propargyl acetates containing a furan ring were prepared by using a CrCl2‐promoted reaction. In the presence of either a AuI or AuIII catalyst, a tandem 3,3‐rearrangement/transannular [4+3] cycloaddition reaction occurred to give propargyl acetates that are regio‐ and diastereospecific. The regiochemistry of the product is controlled by the position of the acetoxy group in the starting material and the stereochemistry of the reaction depends on the ring size. 相似文献
6.
Total Synthesis of Gracilioether F: Development and Application of Lewis Acid Promoted Ketene–Alkene [2+2] Cycloadditions and Late‐Stage CH Oxidation 下载免费PDF全文
Christopher M. Rasik Prof. M. Kevin Brown 《Angewandte Chemie (International ed. in English)》2014,53(52):14522-14526
The first synthesis of gracilioether F, a polyketide natural product with an unusual tricyclic core and five contiguous stereocenters, is described. Key steps of the synthesis include a Lewis acid promoted ketene–alkene [2+2] cycloaddition and a late‐stage carboxylic acid directed C(sp3)? H oxidation. The synthesis requires only eight steps from norbornadiene. 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
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Guangri Yu Prof. Dr. Byunghyuck Jung Prof. Dr. Hee‐Seung Lee Prof. Dr. Sung Ho Kang 《Angewandte Chemie (International ed. in English)》2016,55(7):2573-2576
The first total synthesis of inostamycin A is described. With efficient and stereoselective synthetic routes to aldehyde 3 and ketone 4 developed through asymmetric aldol reactions, addition reactions and reduction, and with chiral building blocks, the two large fragments were coupled with remarkable anti stereoselectivity and efficiency by aldol condensation. The coupling reaction provided the complete carbon skeleton with all the requisite functional groups and stereogenic centers for inostamycin A. The two quaternary carbons at C20 and C16 of ketone 4 were elaborated in a highly stereocontrolled manner by addition reactions of the transmetallated 5 to ethyl ketone 6 and the transmetallated 7 to methyl ketone 8 , respectively, in which the use of LaCl3 for transmetallation was critical for high coupling efficiency. 相似文献
10.
Stanley Chang Soo Hur Prof. Robert Britton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16646-16653
The total synthesis of the marine fungus‐derived natural product ascospiroketal is described. This concise synthesis relies on a unique AgI‐promoted tandem cascade cyclization that provides direct access to the correctly configured tricyclic core of the natural product from a linear precursor. The synthesis of candidate stereostructures of ascospiroketal A allowed for the confident assignment of both the relative and absolute stereochemistry of this unusual octaketide. 相似文献
11.
Short Chemoenzymatic Total Synthesis of ent‐Hydromorphone: An Oxidative Dearomatization/Intramolecular [4+2] Cycloaddition/Amination Sequence 下载免费PDF全文
Vimal Varghese Prof. Tomas Hudlicky 《Angewandte Chemie (International ed. in English)》2014,53(17):4355-4358
A short synthesis of ent‐hydromorphone has been achieved in twelve steps from β‐bromoethylbenzene. The key transformations involved the enzymatic dihydroxylation of the arene to the corresponding cis‐dihydrodiol, Mitsunobu coupling with the ring A fragment, oxidative dearomatization of the C3 phenol, and the subsequent [4+2] cycloaddition to form ring B of the morphinan. The synthesis was completed by intramolecular amination at C9. 相似文献
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Dr. Amit B. Pawar Prof. Dr. Kavirayani R. Prasad 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(47):15202-15206
A formal total synthesis of the 20‐membered marine macrolide, palmerolide A from chiral pool tartaric acid is described. Elaboration of a γ‐hydroxy amide, which is derived from the desymmetrization of tartaric acid amide, and Boord olefination are the pivotal reactions employed for the synthesis of the chiral building blocks, and Stille coupling and ring‐closing metathesis (RCM) are used to assemble the macrolactone. 相似文献
14.
Asymmetric Total Synthesis of Propindilactone G,Part 3: The Final Phase and Completion of the Synthesis 下载免费PDF全文
Xin‐Ting Liang Dr. Lin You Yuan‐He Li Hai‐Xin Yu Prof. Dr. Jia‐Hua Chen Prof. Dr. Zhen Yang 《化学:亚洲杂志》2016,11(9):1425-1435
Two independent synthetic approaches were evaluated for the final phase of the asymmetric total synthesis of propindilactone G ( 1 ). The key steps that led to the completion of the asymmetric total synthesis included: 1) an intermolecular oxidative heterocoupling reaction of enolsilanes to link the core structure to the side chain; 2) an intermolecular Wittig reaction for the formation of the α,β,γ,δ‐unsaturated ester; and 3) a regio‐ and stereoselective OsO4‐catalyzed dihydroxylation of an α,β,γ,δ‐unsaturated enone, followed by an intramolecular lactonization reaction to afford the final product. These reactions enabled the synthesis of (+)‐propindilactone G in only 20 steps. As a consequence of our synthetic studies, the structure of (+)‐propindilactone G has been revised. Furthermore, the direct oxidative coupling strategy for ligation of the core of propindilactone G with its side chain may find application in the syntheses of other natural products and complex molecules. 相似文献
15.
Ming Gao Ye‐Cheng Wang Kai‐Rui Yang Dr. Wei He Prof. Dr. Xiao‐Liang Yang Prof. Dr. Zhu‐Jun Yao 《Angewandte Chemie (International ed. in English)》2018,57(40):13313-13318
The first and enantioselective total synthesis of (+)‐plumisclerin A, a novel unique complex cytotoxic marine diterpenoid, has been accomplished. Around the central cyclopentane anchorage, a sequential ring‐formation protocol was adopted to generate the characteristic tricycle[4.3.1.01,5]decane and trans‐fused dihyrdopyran moiety. Scalable enantioselective LaIII‐catalyzed Michael reaction, palladium(0)‐catalyzed carbonylation and SmI2‐mediated radical conjugate addition were successfully applied in the synthesis, affording multiple grams of the complex and rigid B/C/D‐ring system having six continuous stereogenic centers and two all‐carbon quaternary centers. The trans‐fused dihyrdopyran moiety with an exo side‐chain was furnished in final stage through sequential redox transformations from a lactone precursor, which overcome the largish steric strain of the dense multiring system. The reported total synthesis also confirms the absolute chemistries of natural (+)‐plumisclerin A. 相似文献
16.
Anh Le Saswata Gupta Man Xu Prof. Yuanzhi Xia Prof. Daesung Lee 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(56):e202202015
A new [4+2] cycloaddition of allenyne-alkyne is developed. The reaction is believed to proceed with forming an α,3-dehydrotoluene intermediate. This species behaves as a σπ-diradical to react with a hydrogen atom donor, whereas it displays a zwitterionic reactivity toward weak nucleophiles. The efficiency of trapping α,3-dehydrotoluene depends not only on its substituents but also the trapping agents. Notable features of the reaction are the activating role of the extra alkyne of the 1,3-diyne that reacts with the allenyne moiety and the opposite mode of trapping with oxygen and nitrogen nucleophiles. Oxygen nucleophiles result in the oxygen-end incorporation at the benzylic position of the α,3-dehydrotoluene, whereas with amine nucleophiles the nitrogen-end is incorporated into the aromatic core. Relying on the allenyne-alkyne cycloaddition as an enabling strategy, a concise total synthesis of phosphodiesterase-4 inhibitory selaginpulvilin A is realized. 相似文献
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K. C. Nicolaou Prof. Dr. Yefeng Tang Dr. Jianhua Wang 《Angewandte Chemie (International ed. in English)》2009,48(19):3449-3453
An ocean of discovery : The first total synthesis of the highly oxygenated, marine‐derived, natural product sporolide B has been achieved through a convergent strategy. The key steps involve a ruthenium‐catalyzed [2+2+2] cycloaddition to assemble the indene structural motif and a thermally induced Diels–Alder‐type reaction to forge the macrocycle (see scheme).
19.
Organocatalytic Atroposelective Intramolecular [4+2] Cycloaddition: Synthesis of Axially Chiral Heterobiaryls 下载免费PDF全文
Yidong Liu Xiaoyan Wu Shan Li Lu Xue Chunhui Shan Zhengxing Zhao Prof. Dr. Hailong Yan 《Angewandte Chemie (International ed. in English)》2018,57(22):6491-6495
The enantioselective construction of axially chiral aryl‐naphthopyran skeletons was realized by organocatalytic atroposelective intramolecular [4+2] cycloaddition of in situ generated vinylidene ortho‐quinone methides, from 2‐ethynylphenol derivatives, with alkynes. Through this method, the heteroatropisomers were obtained with excellent yields and enantioselectivities. Moreover, a speculative model of the stereochemical outcome is proposed based on preliminary mechanistic studies. The products having various functional groups can be easily transformed into valuable intermediates as either potential ligands or organocatalysts. 相似文献
20.
Dr. Yukihito Sugano Dr. Fumiaki Kikuchi Akinori Toita Prof. Dr. Seiichi Nakamura Prof. Dr. Shunichi Hashimoto 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(31):9682-9690
The total syntheses of (+)‐polygalolide A and (+)‐polygalolide B have been completed by using a carbonyl ylide cycloaddition strategy. Three of the four stereocenters, including two consecutive tetrasubstituted carbon atoms at C2 and C8, were incorporated through internal asymmetric induction from the stereocenter at C7 by a [Rh2(OAc)4]‐catalyzed carbonyl ylide formation/intramolecular 1,3‐dipolar cycloaddition sequence. The arylmethylidene moiety of these natural products was successfully installed by a Mukaiyama aldol‐type reaction of a silyl enol ether with a dimethyl acetal, followed by elimination under basic conditions. We have also developed an alternative approach to the carbonyl ylide precursor based on a hetero‐Michael reaction. This approach requires 18 steps, and the natural products were obtained in 9.8 and 9.3 % overall yields. Comparison of specific rotations of the synthetic materials and natural products suggests that polygalolides are biosynthesized in nearly racemic forms through a [5+2] cycloaddition between a fructose‐derived oxypyrylium zwitterion with an isoprene derivative. 相似文献