- TOTAL SYNTHESIS OF N-NORNITIDINE
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The benzophenanthridine alkaloid, N-nornitidine has been synthesized employing a benzyne-vinyl isocyanate cycloaddition as the key transformation.
- Rigby, James H.,Holsworth, Daniel D.
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- Reagent-Free C?H/N?H Cross-Coupling: Regioselective Synthesis of N-Heteroaromatics from Biaryl Aldehydes and NH3
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An unprecedented synthesis of N-heteroaromatics from biaryl aldehydes and NH3 through reagent-free C?H/N?H cross-coupling has been developed. The electrosynthesis uses NH3 as an inexpensive and atom-economic nitrogen donor, requires no oxidizing agents, and allows efficient and regioselective access to a wide range of phenanthridines and structurally related polycyclic N-heteroaromatic products.
- Zhao, Huai-Bo,Liu, Zhan-Jiang,Song, Jinshuai,Xu, Hai-Chao
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- Divergent total syntheses of pseudoberberine and nitidine through C[sbnd]H vinylation and switchable 6π electrocyclizations
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Quaternary protoberberine alkaloids and quaternary benzophenanthridine alkaloids are two biosynthetically related natural product families of biological importance. Although significant advances have been achieved in the synthetic chemistry of these alkal
- Jiang, Xunjin,Zeng, Zhixiong,Shi, Dong,Liu, Chenguang,Zhang, Yandong
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- A concise synthesis of nornitidine via nickel- or palladium-catalyzed annulation
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A concise method to synthesize benzo[c]phenanthridine alkaloid, nornitidine, was developed utilizing nickel- or palladium-catalyzed iminoannulation of an internal alkyne. The advantages of this strategy included readily available starting materials, inexp
- Luo, Yu,Mei, Yuhua,Zhang, Jianbo,Lu, Wei,Tang, Jie
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- A Short Total Synthesis of Benzophenanthridine Alkaloids via a Rhodium(III)-Catalyzed C-H Ring-Opening Reaction
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The biologically important naturally available benzophenanthridines were prepared efficiently in three steps with overall good yields. A new synthetic methodology involving a rhodium(III) catalyzed redox-neutral ring-opening of 7-azabenzonorbornadienes with aromatic aldoximes is developed to synthesize the target molecules. The developed C-H ring-opening reaction is highly diastereoselective and compatible with various sensitive functional group substituted aromatic aldoximes as well as substituted 7-azabenzonorbornadienes. The ring-opening products were transformed into highly sensitive 13,14-dehydrobenzo phenanthridine derivatives by HCl hydrolysis. Subsequently, 13,14-dehydrobenzophenanthridines were converted into biologically important benzophenanthridine alkaloids in the presence of DDQ. A possible reaction mechanism was proposed for the C-H ring-opening reaction and supported by the deuterium labeling studies.
- Aravindan, Narasingan,Jeganmohan, Masilamani
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p. 14826 - 14843
(2021/10/20)
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- The Aryne aza-Diels-Alder Reaction: Flexible Syntheses of Isoquinolines
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(Chemical Equation Presented). Two cascade reactions have been developed for the time-efficient preparation of a variety of functionalized aromatic heterocyclic products exhibiting an isoquinoline core. The approach is based on the normal electron-demand
- Castillo, Juan-Carlos,Quiroga, Jairo,Abonia, Rodrigo,Rodriguez, Jean,Coquerel, Yoann
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supporting information
p. 3374 - 3377
(2015/07/15)
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- Visible-light-promoted iminyl-radical formation from Acyl oximes: A unified approach to pyridines, quinolines, and phenanthridines
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A unified strategy involving visible-light-induced iminyl-radical formation has been established for the construction of pyridines, quinolines, and phenanthridines from acyl oximes. With fac-[Ir(ppy)3] as a photoredox catalyst, the acyl oximes were converted by 1 e- reduction into iminyl radical intermediates, which then underwent intramolecular homolytic aromatic substitution (HAS) to give the N-containing arenes. These reactions proceeded with a broad range of substrates at room temperature in high yield. This strategy of visible-light-induced iminyl-radical formation was successfully applied to a five-step concise synthesis of benzo[c]phenanthridine alkaloids.
- Jiang, Heng,An, Xiaode,Tong, Kun,Zheng, Tianyi,Zhang, Yan,Yu, Shouyun
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p. 4055 - 4059
(2015/03/30)
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- Rapid and convergent assembly of natural benzo[c]phenanthridines by palladium/norbornene catalysis
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A straightforward total synthesis of a small panel of natural benzo[c]phenanthridines is described. The selective coupling of an aryl triflate with a bromobenzylamine by means of palladium/norbornene joint catalysis and a sequential transfer hydrogenation
- Deyris, Pierre-Alexandre,Caneque-Cobo, Tatiana,Gomes, Filipe,Narbonne, Vanessa,Maestri, Giovanni,Malacria, Max
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p. 807 - 815
(2016/09/09)
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- Expeditious approach to pyrrolophenanthridones, phenanthridines, and benzo[ c ]phenanthridines via organocatalytic direct biaryl-coupling promoted by potassium tert -butoxide
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A methodology involving a "transition metal-free" intramolecular biaryl-coupling of o-halo-N-arylbenzylamines has been developed in the presence of potassium tert-butoxide and an organic molecule as catalyst. The reaction appears to proceed through KOtBu-promoted intramolecular homolytic aromatic substitution (HAS). Interestingly, this biaryl coupling also works in the presence of potassium tert-butoxide as sole promoter. On extending our approach further, we found that N-acyl 2-bromo-N-arylbenzylamines undergo a one-pot N-deprotection/biaryl coupling followed by oxidation, thus offering an expeditious route to the phenanthridine and benzo[c]phenanthridine skeletons. The strategy has been applied to a concise synthesis of Amaryllidaceae alkaloids viz. oxoassoanine (1b), anhydrolycorinone (1d), 5,6-dihydrobicolorine (2d), trispheridine (2b), and benzo[c]phenanthridines alkaloids dihydronitidine (3b), dihydrochelerythidine (3d), dihydroavicine (3f), nornitidine (3h), and norchelerythrine (3j).
- De, Subhadip,Mishra, Sourabh,Kakde, Badrinath N.,Dey, Dhananjay,Bisai, Alakesh
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p. 7823 - 7844
(2013/09/12)
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- Formal synthesis of nitidine and NK109 via palladium-catalyzed domino direct arylation/N-arylation of aryl triflates
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The use of aryl triflates as reaction partners in a palladium-catalyzed domino direct arylation/N-arylation provides a great advantage due to the availability of starting materials. Furthermore, it allows expedient access to biologically interesting benzo
- Blanchot, Mathieu,Candito, David A.,Larnaud, Florent,Lautens, Mark
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p. 1486 - 1489
(2011/06/09)
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- Total synthesis of benzo[c]phenanthridine alkaloids based on a microwave-assisted electrocyclic reaction of the aza 6π-electron system and structural revision of broussonpapyrine
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Total syntheses of the des-N-methyl (nor) type of benzo[c]phenanthridine alkaloids 1a-f and 19 and benzo[c]phenanthridine alkaloids, chelerythrine (2d), and broussonpapyrine (2f) were achieved. The key step was the construction of tetracyclic 10,11-dihydrobenzo[c]phenanthridines using a microwave-assisted electrocyclic reaction of the 2-cycloalkenylbenzaldoxime methyl ether 4 as an aza 6π-electron system, which was derived in two steps from a Suzuki-Miyaura cross-coupling reaction of 2-bromobenzaldehyde 6 with 2-(3,4-dihydro-6,7- methylenedioxynaphthyl)boronic acid pinacol ester 7. In addition, the exact structure of broussonpapyrine (2f) (2,3,9,10-tetraoxygenated type) was determined to be chelerythrine (2d).
- Ishihara, Yuhsuke,Azuma, Shuhei,Choshi, Tominari,Kohno, Kakujirou,Ono, Kanako,Tsutsumi, Hiroyuki,Ishizu, Takashi,Hibino, Satoshi
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p. 1320 - 1333
(2011/04/16)
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- A new synthesis of the benzo[c]phenanthridines nornitidine, noravicine, and isodecarine, based on a microwave-assisted electrocyclic reaction of the aza 6π-electron system
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A new and versatile synthetic route to a benzophenanthridine alkaloid was developed by a bond formation between C4b and N5 on the benzo[c]phenanthridine nucleus, using a microwave-assisted electrocyclic reaction of the aza 6π-electron system. This strateg
- Kohno, Kakujiro,Azuma, Shuhei,Choshi, Tominari,Nobuhiro, Junko,Hibino, Satoshi
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scheme or table
p. 590 - 592
(2009/05/27)
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- Synthesis and cytotoxic activities of a new benzo[c]phenanthridine alkaloid, 7-hydroxynitidine, and some 9-oxygenated benzo[c]phenanthridine derivatives.
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[formula: see text] A new benzo[c]phenanthridine alkaloid, 7-hydroxynitidine, was synthesized by a novel synthetic procedure. The cytotoxic activity of this compound against HeLa S3 cells was strong, but not greater than those of its mother compounds, nitidine and NK109. We also synthesized other 9-oxygenated benzo[c]phenanthridine alkaloids, 7-methoxynitidine, 9-demethylnitidine, nitidine, and fagaronine, and tested their cytotoxic activities. These results suggest that the 7-hydroxy group enhances antitumor activity and an 8- or 9-hydroxy group weakens this activity.
- Nakanishi,Suzuki
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p. 985 - 988
(2008/02/09)
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- A versatile synthesis of fully aromatic benzo[c]phenanthridine alkaloids
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A versatile new approach for the synthesis of benzo[c]phenanthridine alkaloids is described and is illustrated by the preparation of eight different alkaloids. The key steps are Smiles rearrangements, which allow easy access to 2-bromo-1-naphthylamines from 2-bromo-1-naphthols, and the attachment of the D-ring unit by Suzuki coupling.
- Geen, Graham R.,Mann, Inderjit S.,Mullane, M. Valerie,McKillop, Alexander
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p. 9875 - 9894
(2007/10/03)
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- A versatile synthesis of benzo[c]phenanthridine alkaloids
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Suzuki coupling between 2-bromo-1-formamidonaphthalenes and arylboronic acids is the key step in a versatile synthesis of benzo[c]phenanthridine alkaloids, illustrated by the synthesis of norallonitidine, nornitidine, noravicine, allonitidine, nitidine and avicine.
- Geen, Graham R.,Mann, Inderjit S.,Mullane, M. Valerie,McKillop, Alexander
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p. 1647 - 1648
(2007/10/03)
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- Benzyne Cyclization Route to Benzophenanthridine Alkaloids. Synthesis of Chelerythrine, Decarine, and Nitidine
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The alkaloids chelerythrine (8b) and decarine (7c) have been synthesized through a benzyne-mediated cyclization of N-(2-halobenzyl)-1-naphthylamines 4 with KNH2 in ammonia/ether.The 7-hydroxybenzophenanthridine structure 16a proposed for the alkaloid fagaridine is questioned on the basis of comparison with a model compound (16b) synthesized by benzyne cyclization.For the 8,9-oxygenated alkaloids like nitidine (8i), this cyclization proceeded poorly, but a dramatic improvement occurred when LDA/THF at -78 deg C was used instead of KNH2/NH3.
- Kessar, Satinder V.,Gupta, Yash P.,Balakrishnan, Prasanna,Sawal, Kewal K.,Mohammad, Taj,Dutt, Mahesh
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p. 1708 - 1713
(2007/10/02)
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- Direct Synthesis of Benzophenanthridines and Benzophenanthridones via SRN1 Reactions
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A straightforward and high-yield route to the 11,12-dihydrobenzophenanthridine (3) and 11,12-dihydrobenzophenanthridone (14) ring systems is based upon an SRN1 reaction between 2-halobenzylamines 1 or 2-halobenzoic acids 11 and enolates derived from tetralones 2.The efficient dehydrogenation of 3 or 14 gives the benzophenthridines 4 or benzophenanthridones 15.Use of properly substituted reactants leads to nitidine, avicine, and fagaronine and to analogues of those natural products.
- Beugelmans, Rene,Chastanet, Jacqueline,Ginsburg, Helene,Quintero-Cortes, Leticia,Roussi, Georges
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p. 4933 - 4938
(2007/10/02)
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