3367-47-3Relevant academic research and scientific papers
β-Amino alcohols from anilines and ethylene glycol through heterogeneous Borrowing Hydrogen reaction
Llabres-Campaner, Pedro J.,Ballesteros-Garrido, Rafael,Ballesteros, Rafael,Abarca, Belén
supporting information, p. 5552 - 5561 (2017/08/22)
Borrowing Hydrogen (BH), also called Hydrogen Autotransfer (HA), reaction with neat ethylene glycol represents a key step in the preparation of β-amino alcohols. However, due to the stability of ethylene glycol, mono-activation has rarely been achieved. Herein, a combination of Pd/C and ZnO is reported as heterogeneous catalyst for this BH/HA reaction. This system results in an extremely air and moisture stable, and economic catalyst able to mono-functionalize ethylene glycol in water, without further activation of the diol. In this work, different diols and aromatic amines have been explored affording a new approach towards amino alcohols. This study reveals how the combination of two solid species can afford interesting catalytic properties in heterogeneous phase. ZnO activates ethylene glycol while Pd/C is the responsible of the BH/HA cycle. This catalytic system has also been found useful to dehydrogenate indoles affording indolines that undergo in situ BH/HA cycle prior to re-aromatization, representing a tandem heterogeneous process.
Nickel-catalysed selective N-arylation or N,N′-diarylation of secondary diamines
Brenner, Eric,Schneider, Rapha?l,Fort, Yves
, p. 6913 - 6924 (2007/10/03)
The selective synthesis of N-aryl or N,N′-diaryl piperazines and trimethylene(bis)piperidines from the corresponding diamines and aryl chlorides using a catalyst combination of Ni(0) associated to 2,2′-bipyridine is described. The Ni/2,2′-bipyridine catalyst is also effective for the sequential arylation of piperazine. The preparation of novel and unsymmetrical 1,4-diaryl piperazines is reported.
Nickel-mediated amination chemistry. Part 2: Selective N-arylation or N,N'-diarylation of piperazine
Brenner, Eric,Schneider, Rapha?l,Fort, Yves
, p. 2881 - 2884 (2007/10/03)
The 2,2'-bipyridine liganded Ni catalyst has revealed a good selectivity in the mono arylation of piperazine starting from aryl chlorides allowing a selective and efficient synthesis of N-arylpiperazines using stoichiometric amounts of reagents. The preparation of N,N'-diaryl substituted piperazines is also described. (C) 2000 Elsevier Science Ltd.
Synthesis of N-arylpiperazines from aryl halides and piperazine under a palladium tri-tert-butylphosphine catalyst
Nishiyama, Masakazu,Yamamoto, Toshihide,Koie, Yasuyuki
, p. 617 - 620 (2007/10/03)
A Pd/P(t-Bu), catalyst system has revealed very high activity and selectivity for the amination of N-(hetero)aryl halides with unprotected piperazine. A wide variety of N-(hetero)arylpiperazines could be prepared using this catalyst. Turnover numbers up to 6400mol/mol have been obtained.
Synthesis and structural characterization of N,N'-diarylpiperazine N,N'-dioxide tetrahydrates (aryl=o-tolyl, p-tolyl, p-chlorophenyl)
Kwok, Chun-Kiu,Mak, Thomas C. W.
, p. 1836 - 1847 (2007/10/02)
The synthesis and X-ray structure determination of N,N'-di(o-tolyl)piperazine N,N'-dioxide tetrahydrate, I, N,N'-di(p-tolyl)piperazine N,N'-dioxide tetrahydrate, II, and N,N'-di(p-chlorophenyl)piperazine N,N'-doxide tetrahydrate, III, are described.Compound I crystallizes in space group P1 with a=7.778(1), b=7.915(2), c=8.919(2) A, α=106.25(2), β=99.56(1), γ=108.80(2) deg, and Z=1.Compound II crystallizes in space group P1 with a=6.558(1), b=7.134(2), c=11.610(3) A; α=73.23(2), β=78.08(2), γ=72.67(2) deg., and Z=1.Compound III crystallizes in space group P21/c with a=9.159(3), b=12.390(4), c=8.339(4) A, β=97.38(3) deg., and Z=2.The structures of I-III were solved by the direct method and refined to R=0.049 (1749 observed MoKα reflections), 0.055 (2651 observed reflections), and 0.035 (1827 observed reflections), respectively.In each case, the N,N'-dioxide molecule occupies a site of symmetry 1.The piperazine ring takes the chair form, with two N-O bonds oriented axially in a trans configuration.The structures are characterized by strong hydrogen bonding between the water molecules, as well as between the N-oxide groups and water molecules, giving rise to puckered layers composed of various combinations of edge-sharing four-membered, six-membered, ten-membered, and twelve-membered rings.The aryl rings, which protrude on both sides of each puckered layer, constitute hydrophobic regions separating the hydrophylic layers in the crystal packing.
