90838-83-8Relevant academic research and scientific papers
Substituted Dihydropyridine Synthesis by Dearomatization of Pyridines
Fliege, Julian,Glorius, Frank,Heusler, Arne,Wagener, Tobias
supporting information, p. 13793 - 13797 (2021/05/13)
Dearomatization is an effective method to transform readily available N-heterocycles into partially saturated motifs. Manipulation of dihydro-derivatives holds great potential and provides access to a variety of semi-saturated N-heterocyclic building blocks. However, current strategies are limited in scope and the use of sensitive reagents restricts the applicability in synthetic laboratories. Herein, we report the synthesis of a broad variety of N-substituted 1,4- and 1,2-dihydropyridines by very mild and selective reduction with amine borane for the first time.
Electron transfer from hexameric copper hydrides
Eberhart, Michael S.,Norton, Jack R.,Zuzek, Ashley,Sattler, Wesley,Ruccolo, Serge
, p. 17262 - 17265 (2014/01/06)
The octahedral core of 84-electron LCuH hexamers does not dissociate appreciably in solution, although their hydride ligands undergo rapid intramolecular rearrangement. The single-electron transfer proposed as an initial step in the reaction of these hexamers with certain substrates has been observed by stopped-flow techniques when [(Ph3P)CuH]6 is treated with a pyridinium cation. The same radical cation has been prepared by the oxidation of [(Ph3P)CuH]6 with Cp* 2Fe+ and its reversible formation observed by cyclic voltammetry; its UV-vis spectrum has been confirmed by spectroelectrochemistry. The 48-electron trimer [(dppbz)CuH]3 has been prepared by use of the chelating ligand 1,2-bis(diphenylphosphino)benzene (dppbz).
Synthesis, electrochemistry, and reactivity of new iridium(III) and rhodium(III) hydrides
Hu, Yue,Li, Ling,Shaw, Anthony P.,Norton, Jack R.,Sattler, Wesley,Rong, Yi
scheme or table, p. 5058 - 5064 (2012/09/05)
Two new iridium hydride complexes, Cp*Ir(2-phenylpyridine)H (Cp* = pentamethylcyclopentadienyl) and Cp*Ir(benzo[h]quinoline)H, and their rhodium analogues Cp*Rh(2-phenylpyridine)H and Cp*Rh(benzo[h]quinoline)H have been prepared from the corresponding chl
An efficient synthesis of chiral isoquinuclidines by Diels - Alder reaction using Lewis acid catalyst
Hirama, Masafumi,Kato, Yuji,Seki, Chigusa,Nakano, Hiroto,Takeshita, Mitsuhiro,Oshikiri, Noriko,Iyoda, Masahiko,Matsuyama, Haruo
experimental part, p. 7618 - 7624 (2011/02/22)
The Diels-Alder reaction of 1,2-dihydropyridine derivatives (1-phenoxycarbonyl-1,2-dihydropyridine 1 or 1-methoxycarbonyl-1,2- dihydropyridine 4) with N-acryloyl (1S)-2,10-camphorsultam (1S)-2 {or N-acryloyl (1R)-2,10-camphorsultam (1R)-2} in the presence of Lewis acid, such as titanium tetrachloride, zirconium tetrachloride, and hafnium tetrachloride afforded the endo-cycloaddition product, 2-azabicyclo[2.2.2]octane derivatives in good yields with excellent diastereoselectivity. The absolute stereochemistry assignment of the endo-cycloaddition product (1S)-5a starting from N-acryloyl (1S)-2,10-camphorsultam (1S)-2 has been established to be (1S,4R,7S) and the reaction mechanism was proposed.
Using a two-step hydride transfer to achieve 1,4-reduction in the catalytic hydrogenation of an Acyl pyridinium cation
Shaw, Anthony P.,Ryland, Bradford L.,Franklin, Mary J.,Norton, Jack R.,Chen, Judy Y.-C.,Hall, Michelle Lynn
experimental part, p. 9668 - 9674 (2009/04/10)
(Chemical Equation Presented) The stoichiometric reduction of N-carbophenoxypyridinium tetraphenylborate (6) by CpRu(P-P)H (Cp = η5-cyclopentadienyl; P-P = dppe, 1,2-bis(diphenylphosphino) ethane, or dppf, 1,1′-bis(diphenylphosphino)ferrocene), and Cp*Ru(P-P)H (Cp* = η5-pentamethylcyclopentadienyl; P-P = dppe) gives mixtures of 1,2- and 1,4-dihydropyridines. The stoichiometric reduction of 6 by Cp*Ru(dppf)H (5) gives only the 1,4-dihydropyridine, and 5 catalyzes the exclusive formation of the 1,4-dihydropyridine from 6, H 2, and 2,2,6,6-tetramethylpiperidine. In the stoichiometric reductions, the ratio of 1,4 to 1,2 product increases as the Ru hydrides become better one-electron reductants, suggesting that the 1,4 product arises from a two-step (e-/H?) hydride transfer. Calculations at the UB3LYP/6-311++G(3df,3pd)//UB3LYP/6-31G* level support this hypothesis, indicating that the spin density in the N-carbophenoxypyridinium radical (13) resides primarily at C4, while the positive charge in 6 resides primarily at C2 and C6. The isomeric dihydropyridines thus result from the operation of different mechanisms: the 1,2 product from a single-step H- transfer and the 1,4 product from a two-step (e-/H?) transfer.
Versatile Synthesis of Dihydroquinolines and Quinoline Quinones Using Cyclobutenediones. Construction of the Pyridoacridine Ring System
Zhang, Dawei,Llorente, Isidro,Liebeskind, Lanny S.
, p. 4330 - 4338 (2007/10/03)
1-BOC-2-lithio-1, 4-dihydropyridines were condensed with 3,4-disubstituted cyclobutenediones to produce 1,2-adducts. Neat thermolysis under oxygen-free conditions produced substituted 1,4-dihydroquinoline hydroquinones in which the tert-butoxy residue of the BOC group was displaced by a phenolic residue, generating an oxazolone ring that functioned to protect both rings of the dihydroquinoline hydroquinone from untimely oxidation. Oxidative aromatization with concomitant loss of the oxazolone ring was achieved using 2 equiv of o-chloranil in acetic acid and provided substituted quinoline quinones in good yields. By use of this strategy, a concise synthesis of the pyridoacridine ring system was achieved.
