- Palladium-catalyzed selective formation of substituted pyrroles from alkene-tethered cyclic oxime esters
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Isoxazol-5(4H)-ones were used as nitrene precursors for the selective formation of trisubstituted pyrroles by applying a palladium-catalyzed decarboxylative ring-reconstruction method. The use of bulky biaryl-type monophosphine ligands was effective for improving the selectivity. Deuterium-labeling experiments suggested a mechanism involving β-hydride elimination followed by reductive elimination from an aza-π-allyl intermediate.
- Okamoto, Kazuhiro,Oda, Tomohiro,Matsushita, Gaku,Shimbayashi, Takuya,Sasakura, Kohei,Ohe, Kouichi
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p. 218 - 231
(2019/04/27)
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- Preparation method of derivatives of pyrrole, imidazole, and oxazole
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The invention relates to a preparation method of derivatives of pyrrole, imidazole, and oxazole. Specifically, in the presence of triphenyl phosphine, various alkenyl azides carry out cyclization reactions to generate derivatives of pyrrole, imidazole, an
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Paragraph 0014; 0015; 0018
(2017/07/19)
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- Method of manufacturing pyrrolecarboxylic
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PROBLEM TO BE SOLVED: To provide a method obtainable of a pyrrole in a good yield. SOLUTION: As shown by chemical reaction formula (1) and chemical reaction formula (2), a β-amino alcohol is reacted with a carbonyl compound or an alcohol in the pres
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Paragraph 0048-0054; 0055-0057
(2016/11/09)
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- Insertion of Nitriles into Zirconocene 1-aza-1,3-diene Complexes: Chemoselective Synthesis of N-H and N-Substituted Pyrroles
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The direct insertion of nitriles into zirconocene-1-aza-1,3-diene complexes provides an efficient, chemoselective, and controllable synthesis of N-H and N-substituted pyrroles upon acidic aqueous work-up. The outcome of the reaction (that is, the formatio
- Yu, Shasha,Xiong, Meijun,Xie, Xin,Liu, Yuanhong
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supporting information
p. 11596 - 11599
(2016/02/19)
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- The dual role of ruthenium and alkali base catalysts in enabling a conceptually new shortcut to N-unsubstituted pyrroles through unmasked α-amino aldehydes
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A virtually salt-free and straightforward bimolecular assembly giving N-unsubstituted pyrroles through fully unmasked α-amino aldehydes, which was enabled by the dual effects of a catalytic ruthenium complex and an alkali metal base, is reported. Either solvent-free or acceptorless dehydrogenation facilitates high atom, step, and pot economy, which are otherwise difficult to achieve in multistep operations involving protection/deprotection.
- Iida, Kazuki,Miura, Takashi,Ando, Junki,Saito, Susumu
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supporting information
p. 1436 - 1439
(2013/06/26)
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- Regioselective synthesis of 2,3,4- or 2,3,5-trisubstituted pyrroles via [3,3] or [1,3] rearrangements of O-vinyl oximes
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The regioselective synthesis of 2,3,4- or 2,3,5-trisubstituted pyrroles has been achieved via [3,3] and [1,3] sigmatropic rearrangements of O-vinyl oximes, respectively. Iridium-catalyzed isomerization of easily prepared O-allyl oximes enables rapid access to O-vinyl oximes. The regioselectivity of pyrrole formation can be controlled by either the identity of the α-substituent or through the addition of an amine base. When enolization is favored, a [3,3] rearrangement followed by a Paal-Knorr cyclization provides a 2,3,4-trisubstituted pyrrole; when enolization is disfavored, a [1,3] rearrangement occurs prior to enolization to produce a 2,3,5-trisubstituted pyrrole after cyclization. Optimization and scope of the O-allyl oxime isomerization and subsequent pyrrole formation are discussed and mechanistic pathways are proposed. Conditions are provided for selecting either the [3,3] rearrangement or the [1,3] rearrangement product with β-ester O-allyl oxime substrates.
- Wang, Heng-Yen,Mueller, Daniel S.,Sachwani, Rachna M.,Kapadia, Rachel,Londino, Hannah N.,Anderson, Laura L.
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supporting information; experimental part
p. 3203 - 3221
(2011/06/24)
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- Photochemistry of N-heterocycles. 7: Light induced reductive ring contractions of sixmembered cyclic iminium ions
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Photochemically induced reductive ring contractions, previously observed for 2,5-dihydro-1,2,4-triazines, have also been verified for 1,4-dihydropyrimidines 2a,b, the dihydro-1,2,4,5-tetrazine 9, and dihydro-1,3,5-triazines 11a,b giving rise to fivemembered fully unsaturated heterocycles (pyrroles 4a,b, imidazoles 13a,b, and triazole 10, respectively). The 1,4-dihydropyrazines 15a-j tend to decompose in acidified 2-propanol in the dark, but on irradiation they also undergo reductive ring contraction furnishing solely the 1,2,5-triarylpyrroles 16a-d rather than the (a priori also possible) isomeric 1,3,4-triarylpyrroles 17a-d. In contrast, the 3,6-diphenylpyrid-azine 18 gives the 4-isopropyl-analogue 19 in low yield upon irradiation in hydrogen chloride saturated 2-propanol. Wiley-VCH Verlag GmbH, 2000.
- Nagy, Jozsef,Madarasz, Zoltan,Rapp, Rudolf,Szoelloesy, Aron,Nyitrai, Jozsef,Doepp, Dietrich
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p. 281 - 290
(2007/10/03)
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- Intermolecular Reductive Cross Coupling of Carbonyl Compounds with Nitriles Induced by Low-valent Titanium
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Intermolecular cross coupling of carbonyl compounds with nitriles promoted by TiCl4-Zn leads to ketones.
- Gao, Ju,Hu, Ming-yang,Chen, Jian-xie,Yuan, Su,Chen, Wei-xing
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p. 1617 - 1620
(2007/10/02)
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