- Collective Synthesis of Phenanthridinone through C-H Activation Involving a Pd-Catalyzed Aryne Multicomponent Reaction
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A palladium-catalyzed multicomponent reaction (MCR) involving aryne, CO, and aniline is established for straightforward assembly of a phenanthridinone scaffold through C-H bond activation. Free combination with multiple kinds of readily available anilines and arynes is facilely achieved for phenanthridinone construction without prefunctionalization. Representative natural products were subsequently synthesized through this MCR strategy highly efficiently. Control experiments and interval NMR tracking revealed the mechanism, particularly the key role of CuF2 in determining the aryne-releasing rate from the precursor in this transformation.
- Feng, Minghao,Tang, Bingqing,Xu, Hong-Xi,Jiang, Xuefeng
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supporting information
p. 4352 - 4355
(2016/11/01)
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- Microwave assisted synthesis of phenanthridinones and dihydrophenanthridines by vasicine/KO: T Bu promoted intramolecular C-H arylation
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A simple, efficient, rapid and transition metal-free methodology has been developed by utilizing vasicine (a natural product), as a catalyst for the synthesis of phenanthridinones and dihydrophenanthridines. The reaction proceeds through intramolecular C-H arylation with aryl halides in the presence of KOtBu as a base under microwave irradiation in sulfolane as a solvent. The reaction proceeds well with various aryl iodides, bromides and more remarkably with less reactive aryl chlorides for 15 minutes, providing the corresponding products in 45-90% yields.
- Sharma, Sushila,Kumar, Manoranjan,Sharma, Shruti,Nayal, Onkar S.,Kumar, Neeraj,Singh, Bikram,Sharma, Upendra
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p. 8536 - 8544
(2016/09/28)
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- Ligand controlled regiodivergent C1 insertion on arynes for construction of phenanthridinone and acridone alkaloids
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A palladium-catalyzed regiodivergent C1 insertion multicomponent reaction involving aryne, CO, and 2-iodoaniline is established to construct the scaffolds of phenanthridinone and acridone alkaloids. Regioselective control is achieved under the guidance of selective ligands. The phenanthridinones are solely obtained under ligand-free condition. In comparison, application of the electron-abundant bidentate ligand dppm afforded the acridones with high efficiency. The release rate of the aryne from the precursor assists the regioselectivity of insertion as well, which was revealed through interval NMR tracking. A plausible mechanism was suggested based on the control experiments. Representative natural products and two types of natural product analogues were synthesized divergently through this tunable method. Divergent alkaloid synthesis: A multicomponent, regioselective approach for palladium-catalyzed C1 insertion is described. This reaction was applied in the divergent synthesis of phenanthridinone and acridone natural product core scaffolds.
- Feng, Minghao,Tang, Bingqing,Wang, Nengzhong,Xu, Hong-Xi,Jiang, Xuefeng
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p. 14960 - 14964
(2016/02/05)
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- Radical cyclization and 1,5-hydrogen transfer in selected aromatic diazonium salts
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2-(Methyl-(3-methyl-1-phenyl-1H-pyrazol-5-yl)carbamoyl)thiophene- 3-diazonium hydrogen sulfate 20, 2-(methyl-(3-methylisoxazol-5-yl)carbamoyl)- benzenediazonium hydrogen sulfate 21 and 2-(methyl(phenyl)carbamoyl)- benzenediazonium hydrogen sulphate 22 were synthesized and reacted with a CuSO4/NaCl/ascorbic acid combination to give complex mixtures. The structures of the reaction products were elucidated, depending upon the pathways followed. Compound 20 almost exclusively afforded an Ar-5 cyclization product and trace amounts of the product derived from a competing Ar-6 Pschorr closure. In the case of compound 21, the Ar-6 cyclization was not observed, while the Ar-5 cyclization and 1,5-hydrogen radical transfer processes equally occurred. Finally, the Ar-6 cyclization was observed as the main process for compound 22, accompanied by the Ar-5 cyclization and, in a much lesser extent, by an 1,5-hydrogen radical transfer process.
- Maggio, Benedetta,Fontana, Gianfranco,Raffa, Demetrio,Ferrante, Francesco,Daidone, Giuseppe
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- KOtBu mediated synthesis of phenanthridinones and dibenzoazepinones
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Synthesis of substituted phenanthridinones and dibenzoazepinones has been realized from 2-halo-benzamides in the presence of potassium tert-butoxide and a catalytic amount of 1,10-phenanthroline or AIBN. This new carbon-carbon bond forming reaction gives direct access to various biaryl lactams containing six- and seven-membered rings chemoselectively. Carbon-carbon coupling seems to proceed by the generation of a radical in the amide ring which leads to C-H arylation of aniline.
- Bhakuni, Bhagat Singh,Kumar, Amit,Balkrishna, Shah Jaimin,Sheikh, Javeed Ahmed,Konar, Sanjit,Kumar, Sangit
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supporting information; experimental part
p. 2838 - 2841
(2012/07/28)
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- Pentafluorophenyl transfer: A new group-transfer reaction in organoborate salts
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Irradiation of isoquinolinium hydroxytris(pentafluorophenyl)borate, 1, and phenanthridium hydroxytris(pentafluorophenyl)borate, 2, in either CH 2Cl2 or CH3CN resulted in C6F 5 transfer to the isoquinolinium and phenanthridium cations, generating 2-methyl-1-(2,3,4,5,6- pentafluorophenyl)-1,2-dihydroisoquinoline, 3, and 2-methyl-1-(2,3,4,5,6-pentafluorophenyl)-1,2-dihydrophenanthridine, 4, respectively. In addition, photogeneration of H2O·B(C 6F5)3 resulted from 1. Photogeneration of C6F5-C6F4H from HO-B(C 6F5)3- and of C6H 5-C6F4H from C6H5- B(C6F5)3- was discovered.
- Hewavitharanage, Priyadarshine,Danilov, Evgeny O.,Neckers, Douglas C.
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p. 10653 - 10659
(2007/10/03)
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- Design, synthesis, application and recovery of a minimally fluorous diaryl diselenide for the catalysis of stannane-mediated radical chain reactions
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The synthesis of a minimally fluorous (52% F) diaryl diselenide is described. On reduction in situ with tributylstannane this diselenide provides a fluorous selenol which is effective in inhibiting a range of stannane-mediated radical rearrangements, including a cyclopropylcarbinyl ring opening. A method for the recovery of the fluorous diselenide involving continuous extraction in a modified, cooled continuous extractor is described.
- Crich, David,Xiaolin, Hao,Lucas, Mathew
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p. 14261 - 14268
(2007/10/03)
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- Inhibition of stannane-mediated radical rearrangements by a recoverable, minimally fluorous selenol
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(equation presented) The preparation of a minimally fluorous diaryl diselenide is described. It is demonstrated that this diselenide, reduced in situ to the corresponding selenol, may be used in conjunction with stannanes to prevent a number of radical rearrangements. A 1 M solution of this selenol used in admixture with Breslow's water-soluble stannane can be used to significantly inhibit a cyclopropylcarbinyl ring opening. The combination of the fluorous selenol and the polar stannane permits recovery of the selenol by continuous fluorous extraction and isolation of a stannane-free hydrocarbon product.
- Crich, David,Hao, Xiaolin,Lucas, Mathew A.
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p. 269 - 271
(2008/02/13)
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- Flash vacuum pyrolysis of some N-benzylbenzotriazoles and N-benzylbenzisoxazolones
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The flash vacuum pyrolysis products of 2-(benzotriazol-l-ylmethyl) benzonitrile, methyl 2-(benzotriazol-lylmethyl)benzoate and the corresponding benzisoxazolones have been characterized. The benzotriazoles lose nitrogen to give diradicals which undergo intramolecular hydrogen-atom transfer or cyclization, while the benzisoxazolones rearrange initially to the corresponding benzaldehyde N-(2-carboxyphenyl)imines which undergo subsequent intramolecular addition reactions.
- Khalafy, Jabbar,Prager, Rolf H.
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p. 925 - 929
(2007/10/03)
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- PHOTOCHEMISTRY OF N-AROYLANTHRANILIC ACIDS
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Irradiation of the N-aroylanthranilic acids (1b), (7), (11), and (15) in the presence of either sodium borohydride or potassium hydroxide afforded a mixture of the dihydrophenanthridones (3a and b), (6), (8), (12), (14), and (16), the phenanthridones (2), (9) and (13), and the biphenyls (4), (10), and (17).
- Naito, Takeaki,Ninomiya, Ichiya
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p. 1705 - 1708
(2007/10/02)
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