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1.
Luke S. Hutchings‐Goetz Chao Yang James W. B. Fyfe Thomas N. Snaddon 《Angewandte Chemie (International ed. in English)》2020,59(40):17556-17564
We describe enantioselective syntheses of strychnos and chelidonium alkaloids. In the first case, indole acetic acid esters were established as excellent partner nucleophiles for enantioselective cooperative isothiourea/Pd catalyzed α‐alkylation. This provides products containing indole‐bearing stereocenters in high yield and with excellent levels of enantioinduction in a manner that is notably independent of the N‐substituent. This led to concise syntheses of (?)‐akuammicine and (?)‐strychnine. In the second case, the poor performance of ortho‐substituted cinnamyl electrophiles in the enantioselective cooperative isothiourea/Ir catalyzed α‐alkylation was overcome by appropriate substituent choice, leading to enantioselective syntheses of (+)‐chelidonine, (+)‐norchelidonine, and (+)‐chelamine. 相似文献
2.
Enantioselective Pd‐Catalyzed Allylic Alkylation Reactions of Dihydropyrido[1,2‐a]indolone Substrates: Efficient Syntheses of (−)‐Goniomitine, (+)‐Aspidospermidine,and (−)‐Quebrachamine
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Beau P. Pritchett Jun Kikuchi Dr. Yoshitaka Numajiri Prof. Dr. Brian M. Stoltz 《Angewandte Chemie (International ed. in English)》2016,55(43):13529-13532
The successful application of dihydropyrido[1,2‐a]indolone (DHPI) substrates in Pd‐catalyzed asymmetric allylic alkylation chemistry facilitates rapid access to multiple alkaloid frameworks in an enantioselective fashion. Strategic bromination at the indole C3 position greatly improved the allylic alkylation chemistry and enabled a highly efficient Negishi cross‐coupling downstream. The first catalytic enantioselective total synthesis of (?)‐goniomitine, along with divergent formal syntheses of (+)‐aspidospermidine and (?)‐quebrachamine, are reported herein. 相似文献
3.
Highly Enantioselective Tandem Michael Addition of Tryptamine‐Derived Oxindoles to Alkynones: Concise Synthesis of Strychnos Alkaloids
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Weigang He Jiadong Hu Pengyan Wang Le Chen Kai Ji Siyu Yang Yin Li Zhilong Xie Prof. Dr. Weiqing Xie 《Angewandte Chemie (International ed. in English)》2018,57(14):3806-3809
A highly enantioselective tandem Michael addition of tryptamine‐derived oxindoles to alkynones was developed by taking advantage of a chiral N,N′‐dioxide Sc(OTf)3 catalyst. The reaction enables the facile preparation of enantioenriched spiro[pyrrolidine‐3,3′‐oxindole] compounds, which provides a novel strategy for the synthesis of monoterpenoid indole alkaloids. As a demonstration, the asymmetric synthesis of strychnos alkaloids [(?)‐tubifoline, (?)‐tubifolidine, (?)‐dehydrotubifoline] was achieved in 10–11 steps. 相似文献
4.
Dr. Hisaaki Zaimoku Dr. Tsuyoshi Taniguchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9613-9619
A new approach for synthesis of fawcettimine‐type Lycopodium alkaloids is described. A divergent strategy was achieved by applying stereoselective Diels–Alder reaction followed by redox‐controlled elaboration. Eventually, (?)‐8‐deoxyserratinine, (+)‐fawcettimine, (?)‐lycopoclavamine‐A, (?)‐serratine, (?)‐lycopoclavamine‐B and (?)‐serratanidine were successfully accessed. 相似文献
5.
Concise Syntheses of bis‐Strychnos Alkaloids (−)‐Sungucine, (−)‐Isosungucine,and (−)‐Strychnogucine B from (−)‐Strychnine
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Dr. Senzhi Zhao Christiana N. Teijaro Heng Chen Dr. Gopal Sirasani Dr. Shivaiah Vaddypally Prof. Dr. Michael J. Zdilla Prof. Dr. Graham E. Dobereiner Prof. Dr. Rodrigo B. Andrade 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11593-11596
The first chemical syntheses of complex, bis‐Strychnos alkaloids (?)‐sungucine ( 1 ), (?)‐isosungucine ( 2 ), and (?)‐strychnogucine B ( 3 ) from (?)‐strychnine ( 4 ) is reported. Key steps included (1) the Polonovski–Potier activation of strychnine N‐oxide; (2) a biomimetic Mannich coupling to forge the signature C23?C5′ bond that joins two monoterpene indole monomers; and (3) a sequential HBr/NaBH3CN‐mediated reduction to fashion the ethylidene moieties in 1 – 3 . DFT calculations were employed to rationalize the regiochemical course of reactions involving strychnine congeners. 相似文献
6.
Irina V. Il'ina Konstantin P. Volcho Dina V. Korchagina Vladimir A. Barkhash Nariman F. Salakhutdinov 《Helvetica chimica acta》2007,90(2):353-368
The reactivity of allyl alcohols of the pinane series and of their epoxides in the presence of montmorillonite clay in intra‐ and intermolecular reactions was studied. Mutual transformations of (+)‐trans‐pinocarveol ((+)‐ 2 ) and (?)‐myrtenol ((?)‐ 3a ) were major reactions of these compounds on askanite–bentonite clay (Schemes 1 and 2). However, the two reactions gave different isomerization products, indicating that the reactivity of the starting alcohol (+)‐ 2 or (?)‐ 3a was different from that of the same compound (+)‐ 2 or (?)‐ 3 formed in the course of the reactions. (?)‐cis‐ and (+)‐trans‐Verbenol ((?)‐ 16 and (+)‐ 12 , resp.), as well as (?)‐cis‐verbenol epoxide ((?)‐ 20 ) reacted with both aliphatic and aromatic aldehydes on askanite–bentonite clay giving various heterocyclic compounds (Schemes 4, 5 and 7); the reaction path depended on the structure of both the terpenoid and the aldehyde. 相似文献
7.
Si‐Hua Hou Adriana Y. Prichina Mengxi Zhang Guangbin Dong 《Angewandte Chemie (International ed. in English)》2020,59(20):7848-7856
To show the synthetic utility of the catalytic C?C activation of less strained substrates, described here are the collective and concise syntheses of the natural products (?)‐microthecaline A, (?)‐leubehanol, (+)‐pseudopteroxazole, (+)‐seco‐pseudopteroxazole, pseudopterosin A–F and G—J aglycones, and (+)‐heritonin. The key step in these syntheses involve a Rh‐catalyzed C?C/C?H activation cascade of 3‐arylcyclopentanones, which provides a rapid and enantioselective route to access the polysubstituted tetrahydronaphthalene cores presented in these natural products. Other important features include 1) the direct C?H amination of the tetralone substrate in the synthesis of (?)‐microthecaline A, 2) the use of phosphoric acid to enhance efficiency and regioselectivity for problematic cyclopentanone substrates in the C?C activation reactions, and 3) the direct conversion of serrulatane into amphilectane diterpenes by an allylic cyclodehydrogenation coupling. 相似文献
8.
We report a full account of our work towards the development of Mo‐catalyzed asymmetric allylic alkylation reactions with 3‐alkyloxindoles as nucleophiles. The reaction is complementary to the Pd‐catalyzed reaction with regard to the scope of oxindole nucleophiles. A number of 3‐alkyloxindoles were alkylated successfully under mild conditions to give products with excellent yields and good‐to‐excellent enantioselectivities. Applications of this method to the preparation of indoline alkaloids such as (?)‐physostigmine, ent‐(?)‐debromoflustramine B, and the indolinoquinoline rings of communesin B are reported. 相似文献
9.
Carlos Pérez‐Balado Dr. Paula Rodríguez‐Graña Ángel R. de Lera Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(38):9928-9937
Homo‐ and heterodimeric bispyrrolidinoindoline diketopiperazine alkaloids have been synthesized following a concise, versatile, and stereoselective route. Highlights of the sequence are a diastereoselective construction of the C3a‐bromo‐hexahydropyrrolo[2,3‐b]indole nucleus, its CoI‐induced C3a? C3a′ dimerization, and the twofold or sequential amide‐bond formation before cyclization to the diketopiperazine of the homo‐ or heterodimeric alkaloids, respectively. Stereochemical diversity is achieved through the choice of the appropriate amino acids combined with the base‐induced epimerization of the C2‐acyl‐hexahydropyrrolo[2,3‐b]indole at C2. According to this strategy, the natural products (+)‐WIN 64821 1 , (+)‐WIN 64745 2 and (+)‐asperdimin 6 as well as analogues ( 5 , 22 , 32 , 44 ) with different relative and absolute configuration have been efficiently synthesized. The flexibility of this synthetic methodology has facilitated the structural revision of the natural product (+)‐asperdimin, whose structure has been corrected to diastereomer 6 . 相似文献
10.
Concise and Enantioselective Total Synthesis of (−)‐Mehranine, (−)‐Methylenebismehranine,and Related Aspidosperma Alkaloids
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Dr. Marius Mewald Dr. Jonathan William Medley Prof. Dr. Mohammad Movassaghi 《Angewandte Chemie (International ed. in English)》2014,53(43):11634-11639
We report an efficient and highly stereoselective strategy for the synthesis of Aspidosperma alkaloids based on the transannular cyclization of a chiral lactam precursor. Three new stereocenters are formed in this key step with excellent diastereoselectivity due to the conformational bias of the cyclization precursor, leading to a versatile pentacyclic intermediate. A subsequent stereoselective epoxidation followed by a mild formamide reduction enabled the first total synthesis of the Aspidosperma alkaloids (?)‐mehranine and (+)‐(6S,7S)‐dihydroxy‐N‐methylaspidospermidine. A late‐stage dimerization of (?)‐mehranine mediated by scandium trifluoromethanesulfonate completed the first total synthesis of (?)‐methylenebismehranine. 相似文献
11.
Biomimetic Total Syntheses of (−)‐Leucoridines A and C through the Dimerization of (−)‐Dihydrovalparicine
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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
12.
An efficient, stereocontrolled total synthesis of the complex indole‐diterpene alkaloid (?)‐21‐isopentenylpaxilline ( 1 ) has been achieved. Key elements of the synthesis include the stereocontrolled construction of the advanced eastern hemisphere (?)‐ 68 , involving a highly efficient union of the eastern and western fragments (?)‐ 68 and 5 exploiting our 2‐substituted indole synthesis, application of the Negishi π cycloalkylation tactic as a new, potentially general protocol for the construction of ring C, and the fragmentation of a β,γ‐epoxy ketone to introduce the tertiary OH group at C(13) in the indole diterpene skeleton. 相似文献
13.
Enantioselective Synthesis of Lepadins A–D from a Phenylglycinol‐Derived Hydroquinolone Lactam
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Prof. Dr. Mercedes Amat Alexandre Pinto Dr. Rosa Griera Prof. Dr. Joan Bosch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12804-12808
The marine alkaloids (?)‐lepadins A–C and (+)‐lepadin D, belonging to two diastereoisomeric series, were synthesized from an (R)‐phenylglycinol‐derived tricyclic lactam via a common cis‐decahydroquinoline intermediate. Crucial aspects of the synthesis are the stereochemical control in the assembly of the cis‐decahydroquinoline platform, in the introduction of the C2 methyl and C3 hydroxy substituents, and in the generation of the C5 stereocenter. 相似文献
14.
Beau P. Pritchett Jun Kikuchi Yoshitaka Numajiri Brian M. Stoltz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(43):13727-13730
The successful application of dihydropyrido[1,2‐a]indolone (DHPI) substrates in Pd‐catalyzed asymmetric allylic alkylation chemistry facilitates rapid access to multiple alkaloid frameworks in an enantioselective fashion. Strategic bromination at the indole C3 position greatly improved the allylic alkylation chemistry and enabled a highly efficient Negishi cross‐coupling downstream. The first catalytic enantioselective total synthesis of (−)‐goniomitine, along with divergent formal syntheses of (+)‐aspidospermidine and (−)‐quebrachamine, are reported herein. 相似文献
15.
The oxidative transformation of (+)-aristoteline ((+)- 5 ) into its metabolites, the recently synthesized indole alkaloids (?)-serratoline ((?)- 6 ), (+)-aristotelone ((+)- 2 ), and (?)-alloaristoteline ((?)- 22 ), was investigated in more detail. It was demonstrated that the diastereoface selectivity of the reaction of (+)- 5 with 3-chloroperbenzoic acid can be altered by variation of the solvent as well as by addition of CF3COOH. The chemoselectivity of the 1,2-rearrangement of the intermediate 3H-indol-3-ol derivatives could be controlled as follows: treatment of 3H-indol-3-ols with aqueous polyphosphoric acid led to the pseudoindoxyl ( = 1,2-dihydro-3H-indol-3-one) derivatives, whereas an analogous treatment of the corresponding O-benzoates furnished exclusively the corresponding, constitutionally isomeric 2-oxindole ( = 1,3-dihydro-2H-indol-2-one) products. Exploitation of these and related findings led to efficient total syntheses of the Aristotelia alkaloid (?)-tasmanine ((?)- 1 ) and of the corresponding unnatural epimer (+)- 12 , as well as of the two pseudoindoxyls (+)-aristotelone ((+)- 2 ) and (?)-2-epiaristotelone ((?)- 11 ). All these transformations were carried out with synthetic (+)-aristoteline ((+)- 5 ) as the single indole alkaloid precursor. 相似文献
16.
Indoles are ubiquitous structures that are found in natural products and biologically active molecules. The synthesis of indoles and indole‐involved synthetic methodologies in organic chemistry have been receiving considerable attention. Indole‐N‐carboxylic acids and derived indole‐N‐carboxamides are intriguing compounds, which have been widely used in organic synthesis, especially in multicomponent reactions and C?H functionalization of indoles. This Minireview summarizes the advances of reactions involving indole‐N‐carboxylic acids and indole‐N‐carboxamides in organic chemistry, and discusses the synthetic potential and perspective of this field. 相似文献
17.
Gärtner M Weihofen R Helmchen G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(27):7605-7622
A broadly applicable route to trans‐2,5‐disubstituted pyrrolidines has been developed. Key steps are an asymmetric iridium‐catalyzed allylic amination, a Suzuki–Miyaura coupling, and an intramolecular aza‐Michael addition. Enantiomeric excesses in the range of 93–99 % ee have been achieved. Total syntheses of the alkaloids (?)‐ 225 C , (+)‐ and (?)‐ 223 H (xenovenine), (+)‐ 223 AB , (+)‐ 195 B , and (+)‐ 223 R have been carried out as applications. 相似文献
18.
An expedient concise total synthesis of (+)‐7‐epigoniodiol, (?)‐8‐epigoniodiol, and (+)‐9‐deoxygoniopypyrone is accomplished. The key transformations include a catalytic hydroxylation and base‐mediated N‐(acetyl)oxazolidinone addition reactions, which could set the consecutive OH motif that is either syn,syn or syn,anti with high diastereoselectivity. Moreover, this approach envisioned to facilitate the synthesis of other representatives of the family with structural and stereochemical variation. 相似文献
19.
Two unusual nitro-substituted hasubanan-type alkaloids, stephalonines J (1) and K (2), together with ten known alkaloids, protostephanine, dehydrostephanine, (-)-stephanine, (-)-isolaureline, R-roemeroline, (+)-pronuciferine, ( +)-stephafine, ( + )-N-acetylstephafine, ( + )-lirioferine, and ( + )-norlirioferine, were isolated from the whole plant of Stephania longa. Their structures were characterized mainly by spectroscopic methods including IR, MS, and NMR experiments, and the structures of 1 and 2 were further confirmed through chemical correlations with the known alkaloids stephalonines A (1a) and B (2a), respectively. 相似文献
20.
Guang Li Cyril Piemontesi Qian Wang Jieping Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2896-2900
Controlling the cis C20/C21 relative stereochemistry remains an unsolved issue in the synthesis of eburnane‐type indole alkaloids. Provided herein is a simple solution to this problem by developing a unified and diastereoselective synthesis of four representative members of this class of natural products, namely, eburnamonine, larutensine, terengganensine B, and melokhanine E. The synthesis features the following key steps: a) an α‐iminol rearrangement transforming the 3‐hydroxyindolenine into spiroindolin‐3‐one, b) a highly diastereoselective conformation‐directed cyclization leading to the melokhanine skeleton with the desired C20/C21 cis stereochemistry, and c) either an aza‐pinacol or an unprecedented α‐aminoketone rearrangement converting spiroindolinone back into the indole skeleton. 相似文献