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1.
Lian‐Dong Guo Xiong‐Zhi Huang Shi‐Peng Luo Wen‐Sen Cao Yuan‐Ping Ruan Jian‐Liang Ye Pei‐Qiang Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(12):4132-4136
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
2.
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
3.
Bioinspired Total Synthesis of the Dimeric Indole Alkaloid (+)‐Haplophytine by Direct Coupling and Late‐Stage Oxidative Rearrangement
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Dr. Hitoshi Satoh Ken‐ichi Ojima Dr. Hirofumi Ueda Prof. Dr. Hidetoshi Tokuyama 《Angewandte Chemie (International ed. in English)》2016,55(48):15157-15161
A bioinspired convergent total synthesis of (+)‐haplophytine, a dimeric indole alkaloid with diazabicyclo[3.3.1]nonane and hexacyclic aspidosperma segments, is described. This synthesis involves the direct coupling of the two segments in a AgNTf2‐mediated Friedel–Crafts reaction and construction of the diazabicyclo[3.3.1]nonane skeleton through late‐stage chemoselective aerobic oxidation of the 1,2‐diaminoethene moiety and a sequential semipinacol‐type rearrangement. 相似文献
4.
Lenka Nezbedov Konstantin Drandarov Christa Werner Manfred Hesse 《Helvetica chimica acta》2000,83(11):2953-2960
The asymmetric synthesis of the unlabeled and [D8]‐labeled terminal precursors, 4 ((−)‐(S)‐dihydroxyverbacine) and 19 , respectively, in the biogenesis of the spermine alkaloids aphelandrine ( 5 ) and orantine ( 6 ), respectively, is described. A partial synthesis of the alkaloid (−)‐(S)‐[(E)‐4‐methoxycinnamoyl]buchnerine ( 10 ) is also presented. 相似文献
5.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(8):2159-2163
Homologation of readily available α‐boryl pyrrolidines with metal carbenoids is especially challenging even when good leaving groups (Cl−) are employed. By performing a solvent switch from Et2O to CHCl3, efficient 1,2‐metalate rearrangement of the intermediate boronate occurs with both halide and ester leaving groups. The methodology was used in the total synthesis of the Stemona alkaloid (−)‐stemaphylline in just 11 steps (longest linear sequence), with high stereocontrol (>20:1 d.r.) and 11 % overall yield. The synthesis also features a late‐stage lithiation–borylation reaction with a tertiary amine containing carbenoid. 相似文献
6.
FeCl3‐Mediated Three‐Component Cascade Reaction: An Effective Approach to the Construction of Highly Functionalized Pyrrolo[1,2‐c]quinazolinones
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Hu‐Fei Zheng Dr. Zhi‐Hua Yu Wei Yuan Prof. Dr. Zi‐Long Tang John Clough Yu‐Cheng Gu Prof. Dr. De‐Qing Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(6):1711-1719
An unexpected FeCl3‐mediated three‐component cascade reaction has been used to construct structurally diverse pyrrolo[1,2‐c]quinazolinone derivatives with potential biological activities. This method has advantages of mild conditions, simple work‐up, as well as wide substrate scope, which makes it a powerful approach to the synthesis of diverse pyrrolo[1,2‐c]quinazolinones. This cascade reaction involves 1,3‐dipolar cycloaddition between azomethine ylides and allenoates, followed by intramolecular nucleophilic addition in the presence of FeCl3. The obtained products could be easily transformed into derivatives with the pyrrolo[2,3‐c]quinazoline alkaloid skeleton. 相似文献
7.
Bioinspired Oxidative Cyclization of the Geissoschizine Skeleton for the Total Synthesis of (−)‐17‐nor‐Excelsinidine
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Maxime Jarret Dr. Aurélien Tap Prof. Cyrille Kouklovsky Prof. Erwan Poupon Dr. Laurent Evanno Dr. Guillaume Vincent 《Angewandte Chemie (International ed. in English)》2018,57(38):12294-12298
We report the first total synthesis of (?)‐17‐nor‐excelsinidine, a zwitterionic monoterpene indole alkaloid that displays an unusual N4?C16 connection. Inspired by the postulated biosynthesis, we explored an oxidative coupling approach from the geissoschizine framework to forge the key ammonium–acetate connection. Two strategies allowed us to achieve this goal, namely an intramolecular nucleophilic substitution on a 16‐chlorolactam with the N4 nitrogen atom or a direct I2‐mediated N4?C16 oxidative coupling from the enolate of geissoschizine. 相似文献
8.
Asymmetric Desymmetrization via Metal‐Free C−F Bond Activation: Synthesis of 3,5‐Diaryl‐5‐fluoromethyloxazolidin‐2‐ones with Quaternary Carbon Centers
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Junki Tanaka Satoru Suzuki Etsuko Tokunaga Prof. Dr. Günter Haufe Prof. Dr. Norio Shibata 《Angewandte Chemie (International ed. in English)》2016,55(32):9432-9436
We disclose the first asymmetric activation of a non‐activated aliphatic C?F bond in which a conceptually new desymmetrization of 1,3‐difluorides by silicon‐induced selective C?F bond scission is a key step. The combination of a cinchona alkaloid based chiral ammonium bifluoride catalyst and N,O‐bis(trimethylsilyl)acetoamide (BSA) as the silicon reagent enabled the efficient catalytic cycle of asymmetric Csp3?F bond cleavage under mild conditions with high enantioselectivities. The ortho effect of the aryl group at the prostereogenic center is remarkable. This concept was applied for the asymmetric synthesis of promising agrochemical compounds, 3,5‐diaryl‐5‐fluoromethyloxazolidin‐2‐ones bearing a quaternary carbon center. 相似文献
9.
A novel, short, and highly stereoselective synthesis of the macrocyclic spermidine alkaloid (+)‐(S)‐dihydroperiphylline ( 15 ) is described. The key synthetic steps were the stereoselective addition of the chiral amine 1 to the cinnamate 2 and cyclization of the bis[toluene‐4‐sulfonamide] precursor 12 in the presence of Cs2CO3 as a template. Unambiguous assignments of the signals in both the 1H‐ and 13C‐NMR spectra of 15 were achieved by 2D NMR spectra. 相似文献
10.
Direct Asymmetric Mannich‐Type Reaction of α‐Isocyanoacetates with Ketimines using Cinchona Alkaloid/Copper(II) Catalysts
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Masashi Hayashi Masaru Iwanaga Noriyuki Shiomi Dr. Daisuke Nakane Prof. Dr. Hideki Masuda Prof. Dr. Shuichi Nakamura 《Angewandte Chemie (International ed. in English)》2014,53(32):8411-8415
The enantioselective direct Mannich‐type reaction of ketimines with α‐isocyanoacetates has been developed. Excellent yields and enantioselectivity were observed for the reaction of various ketimines and α‐isocyanoacetates using cinchona alkaloid/Cu(OTf)2 and a base. Both enantiomers of the products could be obtained by using pseudoenantiomeric chiral catalysts. This process offers an efficient route for the synthesis of α,β‐diamino acids. 相似文献
11.
Oxidative C−H/C−H Cross‐Coupling Reactions between N‐Acylanilines and Benzamides Enabled by a Cp*‐Free RhCl3/TFA Catalytic System
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Yang Shi Luoqiang Zhang Prof. Dr. Jingbo Lan Min Zhang Fulin Zhou Wenlong Wei Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2018,57(29):9108-9112
By making use of a dual‐chelation‐assisted strategy, a completely regiocontrolled oxidative C?H/C?H cross‐coupling reaction between an N‐acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step‐economic and highly efficient pathway to 2‐amino‐2′‐carboxybiaryl scaffolds from readily available substrates. A Cp*‐free RhCl3/TFA catalytic system was developed to replace the [Cp*RhCl2]2/AgSbF6 system generally used in oxidative C?H/C?H cross‐coupling reactions between two (hetero)arenes (Cp*=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl3/TFA system avoids the use of the expensive Cp* ligand and AgSbF6. As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield. 相似文献
12.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(26):7592-7595
The first total synthesis of the hexacyclic indole alkaloid (±)‐corymine is described. Starting from the readily available N‐protected tryptamine, the title compound was achieved in 21 steps in 3.4 % overall yield. Key steps of the synthesis include: a) the addition of a malonate to a 3‐bromooxindole to afford 3,3‐disubstituted oxindole, b) the formation of a 12‐membered cyclic enol ether by intramolecular O‐propargylation, immediately followed by propargyl Claisen rearrangement to provide the α‐allenyl ketone stereospecifically, c) DMDO oxidation to install a hydroxy group in a highly stereoselective manner, and d) the SmI2‐mediated reductive C−O bond cleavage to remove the α‐keto carboxyl group. 相似文献
13.
An Alternate Synthesis of 6H‐Indolo[2,3‐b]quinoline via One‐Pot Alkylation–Dehydration–Cyclization–Aromatization Approach
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A simple, straightforward and efficient synthesis of 6H‐indolo[2,3‐b]quinoline, a natural product isolated from leaves of Justicia betonica, is achieved through a pivalic acid‐assisted one‐pot alkylation–dehydration–cyclization–aromatization approach. This synthesis constitutes a formal approach toward a biologically important alkaloid neocryptolepine. 相似文献
14.
A convergent total synthesis of 13‐hydroxyisocyclocelabenzine was developed. (3S)‐Methyl 3‐amino‐3‐phenylpropanoate ( 4 ) was used as the chiral building block. The 3,4‐dihydro‐4‐hydroxyisoquinolin‐1(2H)‐one derivative ( 5 ), the key fragment for the total synthesis, was prepared by a novel base‐catalyzed lactone‐lactam ring enlargement (Scheme 3). The resulting target C(13) epimers 3a / 3b from macrocyclization (Scheme 4) were separated by repeated flash chromatography. The absolute configuration of the synthetic alkaloid was determined by an X‐ray crystal‐structure analysis, which enabled us to determine the absolute configuration (9S,13R) for natural 3a with positive [α]D. 相似文献
15.
Efficient Synthesis of (−)‐Corynoline by Enantioselective Palladium‐Catalyzed α‐Arylation with Sterically Hindered Substrates
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Dr. Xiaofeng Rao Dr. Naikai Li Heng Bai Chaodi Dai Dr. Zheng Wang Prof. Dr. Wenjun Tang 《Angewandte Chemie (International ed. in English)》2018,57(38):12328-12332
Sterically hindered substrates can be employed in an enantioselective palladium‐catalyzed α‐arylation with the chiral monophosphorus ligand BI‐DIME. This process enabled an efficient synthesis of the antidepressant (S)‐nafenodone, a four‐step enantioselective synthesis of the Sceletium alkaloid (+)‐sceletium A‐4, a concise five‐step enantioselective synthesis of (?)‐corynoline, as well as a three‐step preparation of (?)‐DeN‐corynoline. 相似文献
16.
The Diels? Alder reaction of 1,4‐benzoquinone with 1,3‐dienes catalyzed by Mikami's [Ti{(S)‐binol(2?)}Cl2] complex (binol=[1,1′‐binaphthalene]‐2,2′‐diol) gives cycloadducts in good yield and in high enantiomer excess. A model is proposed to explain the observed absolute configuration of cycloadducts, and the reaction is used as the key step in an asymmetric synthesis leading to the alkaloid (?)‐ibogamine. 相似文献
17.
The RhII‐catalyzed cycloaddition cascade of an indolyl‐substituted α‐diazo imide was used for the total synthesis of the complex pentacyclic alkaloid (±)‐aspidophytine. Treatment of the resulting dipolar cycloadduct with BF3?OEt2 induces a domino fragmentation cascade. The reaction proceeds by an initial cleavage of the oxabicyclic ring and formation of a transient N‐acyl iminium ion which reacts further with the adjacent tert‐butyl ester and sets the required lactone ring present in aspidophytine. A three‐step sequence was then used to remove both the ester and OH groups. Subsequent functional group manipulations allowed for the high‐yielding conversion to (±)‐aspidophytine. 相似文献
18.
Dr. Pavel A. Donets Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2015,54(2):633-637
The 1,6‐annulated 2‐pyridone motif is found in many biologically active compounds and its close relation to the indolizidine and quinolizidine alkaloid core makes it an attractive building block. A nickel‐catalyzed C? H functionalization of 2‐pyridones and subsequent cyclization affords 1,6‐annulated 2‐pyridones by selective intramolecular olefin hydroarylation. The switch between the exo‐ and endo‐cyclization modes is controlled by two complementary sets of ligands. Irrespective of the ring size, the regioselectivity during the cyclization is under full catalyst control. Simple cyclooctadiene promotes an exo‐selective cyclization, whereas a bulky N‐heterocyclic carbene ligand results in an endo‐selective mode. The method was further applied in the synthesis of the lupin alkaloid cytisine. 相似文献
19.
《Journal of heterocyclic chemistry》2018,55(4):1048-1052
An efficient synthesis of 6‐oxo‐1,2,3,4,5,7,12,12 b ‐octahydroindolo[2,3‐ α ]quinolizine from 2‐acetylpyridine and phenylhydrazine is described. This derivative of the natural alkaloid desbromoarborescidine A is an important entry point to the sarpagine‐vobasine family of plant alkaloids. 相似文献
20.
An aerobic radical approach for the synthesis of unsymmetrical heteroaryl ketones is described herein. The reaction involves cross‐dehydrogenative coupling between aldehydes and heteroaromatic bases with molecular oxygen (O2). The key aspect of the method is the generation of reactive acyl radical via homolytic activation of aldehyde C?H bond using O2 as the sole oxidant. The reaction has a good substrate scope with respect to aldehydes and functionalized nitrogen heterocycles. Based on our mechanistic studies, a radical chain pathway is suggested for the reaction. A synthetic application of the method is demonstrated in the formal synthesis of natural alkaloid (±) angustureine. 相似文献