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本文对[4+ 3 ]环加成反应体系以及最近在合成中的应用进行了综述, 并对进一步研究的方向进行了讨论。 相似文献
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Ruthenium(0)‐Catalyzed [4+2] Cycloaddition of Acetylenic Aldehydes with α‐Ketols: Convergent Construction of Angucycline Ring Systems 下载免费PDF全文
Dr. Aakarsh Saxena Dr. Felix Perez Prof. Michael J. Krische 《Angewandte Chemie (International ed. in English)》2016,55(4):1493-1497
Ruthenium(0) complexes modified by CyJohnPhos or RuPhos catalyze the successive C?C coupling of acetylenic aldehydes with α‐ketols to form [4+2] cycloadducts as single diastereomers. This method enables convergent construction of type II polyketide ring systems of the angucycline class. 相似文献
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Dongshun Ni Brittany P. Witherspoon Hong Zhang Chen Zhou K. N. Houk M. Kevin Brown 《Angewandte Chemie (International ed. in English)》2020,59(28):11432-11439
A method for the stereoselective [4+2]‐cycloaddition of alkenylboranes and dienes is presented. This transformation was accomplished through the introduction of a new strategy that involves the use of chiral N‐protonated alkenyl oxazaborolidines as dieneophiles. The reaction leads to the formation of products that can be readily derivatized to more complex structural motifs through stereospecific transformations of the C?B bond such as oxidation and homologation. Detailed computation evaluation of the reaction has uncovered a surprising role of the counterion on stereoselectivity. 相似文献
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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
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Xuelei Jia Honghui Lei Feipeng Han Tao Zhang Ying Chen Zhengshuang Xu Pratanphorn Nakliang Sun Choi Yian Guo Tao Ye 《Angewandte Chemie (International ed. in English)》2020,59(31):12832-12836
A concise and asymmetric total synthesis of five kopsane alkaloids that share a unique heptacyclic caged ring system was accomplished. The key transformation in the sequence involved a remarkable PtCl2‐catalyzed intramolecular [3+2] cycloaddition, which allowed for the rapid assembly of pentacyclic carbon skeletons bearing 2,3‐quaternary functionalized indoline. Expeditious construction of diverse indoline scaffolds with excellent control of diastereoselectivity demonstrated the broad scope and versatility of this key transformation. 相似文献
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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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Zhuo Xin Dr. Søren Kramer Dr. Jacob Overgaard Prof. Dr. Troels Skrydstrup 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):7926-7930
A new synthetic route to the privileged 1,2‐dihydroisoquinolines is reported. This method, which relies on a gold‐catalyzed formal [4+2] cycloaddition between ynamides and imines, provides a new retrosynthetic disconnection of the 1,2‐dihydroisoquinoline core by installing the 1,8a C?C and 2,3 C?N bonds in one step. Both aldimines and ketimines can be used as substrates. In addition, one example of dihydrofuropyridine synthesis is also demonstrated. 相似文献
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Formal Synthesis of Sarain A: Intramolecular Cycloaddition of an Eight‐Membered Cyclic Nitrone to Construct the 2‐Azabicyclo[3.3.1]nonane Framework 下载免费PDF全文
Dr. Takuya Higo Tomoya Ukegawa Dr. Satoshi Yokoshima Prof. Tohru Fukuyama 《Angewandte Chemie (International ed. in English)》2015,54(25):7367-7370
An enantioselective route to the tetracyclic skeleton of sarain A has been developed. Asymmetric reduction of an ynone introduced a chiral center which was transferred to the contiguous tertiary stereogenic centers through an Ireland–Claisen rearrangement. The 2‐azabicyclo[3.3.1]nonane framework was constructed by an unprecedented intramolecular cycloaddition of an eight‐membered cyclic nitrone. Using the steric bias of the bicyclic system, the quaternary carbon atom was constructed by a stereoselective aldol reaction. Further ring formations were performed by ring‐closing metathesis for the 13‐membered ring and an iodoamidation reaction for the pyrrolidine ring. The present synthesis has successfully provided an alternative route to the late‐stage intermediate of Overman’s synthesis. 相似文献
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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
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Total Synthesis of (+/−)‐Frondosin B and (+/−)‐5‐epi‐Liphagal by Using a Concise (4+3) Cycloaddition Approach 下载免费PDF全文
Duchan R. Laplace Bart Verbraeken Prof. Dr. Kristof Van Hecke Prof. Dr. Johan M. Winne 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):253-262
A recently developed (4+3) cycloaddition between dienes and furfuryl alcohols, as precursors of oxyallyl‐type cations, has been used as a key step in the racemic syntheses of two natural products: frondosin B and liphagal. This work demonstrates the synthetic potential of this cycloaddition reaction, and offers a short synthetic route to an interesting family of natural products. A full account of these synthetic studies is presented, further illustrating the mechanism, scope, and limitations of this straightforward synthetic method for seven‐membered rings. 相似文献
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Enantioselective Synthesis of [9]‐ and [11]Helicene‐like Molecules: Double Intramolecular [2+2+2] Cycloaddition 下载免费PDF全文
Yuki Kimura Naohiro Fukawa Yuta Miyauchi Prof. Dr. Keiichi Noguchi Prof. Dr. Ken Tanaka 《Angewandte Chemie (International ed. in English)》2014,53(32):8480-8483
The enantioselective synthesis of completely ortho‐fused [9]‐ and [11]helicene‐like molecules has been achieved through a rhodium‐mediated, intramolecular, double [2+2+2] cycloaddition of phenol‐ or 2‐naphthol‐linked hexaynes. Crystal structures and photophysical properties of these [9]‐ and [11]helicene‐like molecules have also been disclosed. 相似文献
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Dr. Vera J. Meyer Christoph Ascheberg Prof. Meike Niggemann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6371-6374
A formal intermolecular [2+2+2] cycloaddition reaction of enynes to aldehydes is presented, which can be realized in the presence of a simple and benign calcium catalyst. The reaction proceeds with excellent chemo, regio‐ and diastereoselectivity and leads to a one‐step assembly of highly interesting bicyclic building blocks containing up to three stereocenters from simple precursors via a new type of skeletal rearrangement of enynes. The observed diastereoselectivity is accounted for by two different mechanistic proposals. The first one engages mechanistic prospects arising from a gold catalyzed reaction in the absence of the stabilizing gold substituent. The second proposal involves an unprecedented cyclization–carbonyl allene ene reaction–hydroalkoxylation cascade. 相似文献
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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
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综述了亚甲胺叶立德的制备、它参与的[3+2]环加成反应的反应机理、反应选择性及在天然产物全合成中的应用等方面的最新进展. 相似文献
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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