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1.
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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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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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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Robert T. Yu Ernest E. Lee Dr. Guillaume Malik Tomislav Rovis Prof. 《Angewandte Chemie (International ed. in English)》2009,48(13):2379-2382
CO! You had me at hello : The use of chiral biphenyl‐based phosphoramidite ligands on rhodium provides an efficient [2+2+2] cycloaddition between terminal alkyl alkynes and alkenyl isocyanates (see scheme). The cycloaddition proceeds through a CO migration pathway, and facilitates a rapid four‐step asymmetric synthesis of indolizidine (?)‐209D.
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Haoxuan Wang Prof. Sarah E. Reisman 《Angewandte Chemie (International ed. in English)》2014,53(24):6206-6210
The concise total syntheses of the bis(pyrroloindolines) (?)‐lansai B and (+)‐ nocardioazines A and B are reported. The key pyrroloindoline building blocks are rapidly prepared by enantioselective formal [3+2] cycloaddition reactions. The macrocycle of (+)‐nocardioazine A is constructed by an unusual intramolecular diketopiperazine formation. 相似文献
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Prof. Dr. J. Stephen Clark Dr. Chao Xu 《Angewandte Chemie (International ed. in English)》2016,55(13):4332-4335
A highly efficient 12‐step synthesis of the marine alkaloid (?)‐nakadomarin A has been accomplished. The key advanced intermediate, a tetracyclic ketone derivative, was constructed in just seven steps using a sequence that includes an asymmetric Pauson–Khand reaction, an Overman rearrangement reaction, a ring‐closing metathesis reaction, and an amination reaction. Late introduction of the furan ring during the synthesis of (?)‐nakadomarin A means that the key tetracyclic ketone derivative has the potential to serve as an advanced intermediate for the synthesis of related marine alkaloids. 相似文献
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Lian‐Dong Guo Xiong‐Zhi Huang Shi‐Peng Luo Wen‐Sen Cao Prof. Yuan‐Ping Ruan Dr. Jian‐Liang Ye Prof. Dr. Pei‐Qiang Huang 《Angewandte Chemie (International ed. in English)》2016,55(12):4064-4068
The first total synthesis of the alkaloid (?)‐haliclonin A is reported. The asymmetric synthesis relied on a novel organocatalytic asymmetric conjugate addition of nitromethane with 3‐alkenyl cyclohex‐2‐enone to set the stereochemistry of the all‐carbon quaternary stereogenic center. The synthesis also features a Pd‐promoted cyclization to form the 3‐azabicyclo[3,3,1]nonane core, a SmI2‐mediated intermolecular reductive coupling of enone with aldehyde to form the requisite secondary chiral alcohol, ring‐closing alkene and alkyne metathesis reactions to build the two aza‐macrocyclic ring systems, and an unprecedented direct transformation of enol into enone. 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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Prof. Dr. Pauline Chiu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(41):14287-14291
An efficient formal total synthesis of (+) cortistatins A and J has been accomplished, by exploiting a highly diastereoselective intramolecular [4+3] cycloaddition of epoxy enolsilanes as the key reaction to construct rings B and C of the cortistatins in one step. 相似文献
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Cover Picture: Short Chemoenzymatic Total Synthesis of ent‐Hydromorphone: An Oxidative Dearomatization/Intramolecular [4+2] Cycloaddition/Amination Sequence (Angew. Chem. Int. Ed. 17/2014) 下载免费PDF全文
Vimal Varghese Prof. Tomas Hudlicky 《Angewandte Chemie (International ed. in English)》2014,53(17):4251-4251
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Visible‐Light‐Induced Formal [3+2] Cycloaddition for Pyrrole Synthesis under Metal‐Free Conditions 下载免费PDF全文
Jun Xuan Xu‐Dong Xia Ting‐Ting Zeng Zhu‐Jia Feng Prof. Dr. Jia‐Rong Chen Dr. Liang‐Qiu Lu Prof. Dr. Wen‐Jing Xiao 《Angewandte Chemie (International ed. in English)》2014,53(22):5653-5656
A photocatalytic formal [3+2] cycloaddition of 2H‐azirines with alkynes has been achieved under irradiation by visible light in the presence of organic dye photocatalysts. This transformation provides efficient access to highly functionalized pyrroles in good yields and has been applied to the synthesis of drug analogues. A primary trial of photocascade catalysis merging energy transfer and redox neutral reactions was shown to be successful. 相似文献
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M. Sc. Lennart Brewitz Dr. Josep Llaveria Dr. Akira Yada Prof. Alois Fürstner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(14):4532-4537
A concise and largely catalysis‐based approach to the potent algal toxin polycavernoside A ( 1 ) is described that intercepts a late‐stage intermediate of a previous total synthesis; from there on, this challenging target can be reached in a small number of steps. Key to success was a sequence of a molybdenum‐catalyzed ring‐closing alkyne metathesis (RCAM) reaction to forge the macrocyclic frame, followed by a gold‐catalyzed and strictly regioselective transannular hydroalkoxylation of the resulting cycloalkyne that allows the intricate oxygenation pattern of the macrolactone ring of 1 to be properly set. The required cyclization precursor 5 was assembled by the arguably most advanced fragment coupling process based on an Evans–Tishchenko redox esterification known to date, which was optimized to the extent that the precious coupling partners could be used in an almost equimolar ratio ( 6 / 7 1:1.3). The preparation of these building blocks features, inter alia, the power of the Sc(OTf)3‐catalyzed Leighton crotylation as well as the superb selectivities of alkene cross metathesis, asymmetric keto‐ester hydrogenation, and the Jacobsen epoxidation/epoxide resolution technologies. 相似文献
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Formal Total Synthesis of (−)‐Taxol through Pd‐Catalyzed Eight‐Membered Carbocyclic Ring Formation 下载免费PDF全文
Sho Hirai Masayuki Utsugi Mitsuhiro Iwamoto Prof. Dr. Masahisa Nakada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):355-359
A formal total synthesis of (?)‐taxol by a convergent approach utilizing Pd‐catalyzed intramolecular alkenylation is described. Formation of the eight‐membered carbocyclic ring has been a problem in the convergent total synthesis of taxol but it was solved by the Pd‐catalyzed intramolecular alkenylation of a methyl ketone affording the cyclized product in excellent yield (97 %), indicating the high efficiency of the Pd‐catalyzed intramolecular alkenylation. Rearrangement of the epoxy benzyl ether through a 1,5‐hydride shift, generating the C3 stereogenic center and subsequently forming the C1–C2 benzylidene, was discovered and utilized in the preparation of a substrate for the Pd‐catalyzed reaction. 相似文献