A new method for the preparation of unsymmetrical 1,4-substituted piperazine derivatives
作者:Aurelio Ortiz、Norberto Farfán、Herbert Höpfl、Rosa Santillan、Marı́a E. Ochoa、Atilano Gutiérrez
DOI:10.1016/s0957-4166(99)00049-x
日期:1999.2
Symmetrical and unsymmetrical N,N′-piperazine derivatives of (−)-norephedrine and o-aminophenol were synthesized stereoselectively in yields >70% by reduction of the corresponding N,N′-ethylenebisoxazolidine heterocycles. The stereochemistry at the ring fusion carbons was established by NMR spectroscopy and X-ray crystallography.
Iron(II) Complexes with Tetradentate Bis(aminophenolate) Ligands: Synthesis and Characterization, Solution Behavior, and Reactivity with O<sub>2</sub>
作者:Christopher J. Whiteoak、Rafael Torres Martin de Rosales、Andrew J. P. White、George J. P. Britovsek
DOI:10.1021/ic1016998
日期:2010.12.6
Tetradentate bis(aminophenolate) ligands H2salanX and H2bapenX (where X refers to the para-phenolate substituent = H, Me, F, Cl) react with [FeN(SiMe3)2}2] to form iron(II) complexes, which in the presence of suitable donor ligands L (L = pyridine or THF) can be isolated as the complexes [Fe(salanX)(L)2] and [Fe(bapenX)(L)2]. In the absence of donor ligands, either mononuclear complexes, for example
Synergetic activation of CO<sub>2</sub> by the DBU-organocatalyst and amine substrates towards stable carbamate salts for synthesis of oxazolidinones
作者:Xiao-Chao Chen、Kai-Chun Zhao、Yin-Qing Yao、Yong Lu、Ye Liu
DOI:10.1039/d1cy01298c
日期:——
under mild conditions (80–100 °C, 12 h, 1.0 MPa CO2). Control experiments demonstrated that the formation of an ion-pair carbamate salt intermediate IS-B derived from the reaction of CO2, DBU (catalyst) and an amine (substrate) was the key step for this three-component reaction. The available DBU–amine–CO2 adduct intermediate (like IS-B-2) with fair stability will evolve into the thermodynamically stable
将CO 2转化为有价值的化学品的有效方法的开发引起了关于CO 2利用的挑战性问题的越来越多的关注。在此,DBU 有机超强碱催化CO 2、伯(脂肪族/芳香族)胺和 1,2-二氯乙烷(或其衍生物)制备恶唑烷酮的有效方法在温和条件下获得了 47-97% 的产率(80–100 °C, 12 h, 1.0 MPa CO 2 )。对照实验表明,由 CO 2反应生成的离子对氨基甲酸盐中间体IS-B、DBU(催化剂)和胺(底物)是这种三组分反应的关键步骤。可用的 DBU-胺-CO 2加合物中间体(如IS-B-2)在 1,2-二氯乙烷(或其衍生物)的攻击下,随着 DBU 的再生,将演变成热力学稳定的产物恶唑烷酮催化剂。或者,稳定性相对较差的 DBU-芳胺-CO 2加合物(如IS-B-1)的分解也可能导致 1,2-二氯乙烷(或其衍生物)与芳胺的竞争性取代反应。这项工作提供了对 DBU 催化剂和亲核胺底物协同 CO
SYNTHESES, NMR STUDY AND STEREOCHEMISTRY OF NEW P-H TRICYCLOPHOSPHORANES
作者:Margarita Tlahuextl、Martínez-martínez、María De Jesús Rosales-Hoz、Rosalinda Contreras
DOI:10.1080/10426509708044194
日期:1997.4.1
Abstract Four new tricyclophosphoranes 1b-4b were synthesized derived from N,N′-bis[2-hydroxy phenyl]ethylenediamine (1a), N,N′-bis[2-hydroxyphenyl]oxamide (a), N,N′-bis[(-)-norephedrinelethylene (3a), N,N′-bis[(-)-norpseudoephedrine]oxalyl (4a), The syntheses of compounds 3b and 4b were completely stereoselective giving only one epimer in each case (epimer helix Δ, 3b; helix Λ, 4b). For both the phosphorus
describes the preparation of a series of new 1,4‐diarylsubstituted‐2‐piperazinones by condensation of substituted N,N′‐bis‐(2‐hydroxyphenyl)‐ethylenediamines with glyoxal and the complete 13CNMR spectral assignment accomplished using APT, HMQC and HMBC techniques. Substituent chemical‐shift effects (SCS) were calculated, which showed different values for the lactam‐ and amine‐substituted aromatic rings