Enantiomerically Enriched Bicyclic Hydroxamic Acids in One Step from α-Aminohydroxamic Acids and Keto Acids via Cyclocondensation
摘要:
New enantiomerically enriched bicyclic hydroxamic acids, 1-hydroxy-dihydro-1H-pyrrolo[1,2-a]imidazole-2,5(3H,6H)-diones, have been synthesized by the cyclocondensation of L--aminohydroxamic acids with keto acids in a highly chemo- and stereoselective manner. The cis configuration between the amino acid side chain and the methyl group at C7a in 1H-pyrrolo[1,2-a]imidazole-2,5-dione was unambiguously established by X-ray crystallographic analysis. This method could also be applied to the cyclocondensation with o-formylbenzoic acid, giving a tricyclic hydroxamic acid in a good yield. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) to view the free supplemental file.
Ln III [15-MC CuII(N)pheHA -5] 3+络合物的二十个晶体结构,其中pheHA =苯丙氨酸异羟肟酸,Ln III = Y III和La III –Tm III,除Pm III外,具有硝酸盐氢氧根离子和/或氢氧根阴离子用于评估中心金属离子对金属内凹结构的影响。每个Ln III [15-MC CuII(N)pheHA -5] 3+络合物都是两亲性的,疏水侧由pheHA配体的苯基组成,而一侧没有芳族残基。Ln III [15-MCCuII(N)pheHA -5] 3+复合体。在1型结构中,中心金属离子在金属漆的疏水面上不结合硝酸根阴离子,并且两个相邻的金属漆通过其苯基基团二聚而形成疏水区室。在2型结构中,中心金属离子在疏水面上以双齿形式结合硝酸盐。有两种不同类型的2型金属凹槽,分别命名为A和B。2A型金属凹槽的水分子与亲水面上的中心金属离子键合,而2B型金属凹槽的亲水面
Amino acid derived amides and hydroxamic acids as ligands for asymmetric transfer hydrogenation in aqueous media
作者:Katrin Ahlford、Hans Adolfsson
DOI:10.1016/j.catcom.2011.03.032
日期:2011.7
Amides and hydroxamic acids derived from α-amino acids were evaluated as ligands in combination with rhodium and iridium half-sandwich complexes in asymmetric transferhydrogenation (ATH) of ketones. The reactions were performed in aqueous media using lithium formate as hydride source. The catalyst systems turned out to be highlyefficient and ee's up to 90% were obtained.
Production of hydroxamic acids by immobilized Pseudomonas aeruginosa cells: Kinetic analysis in reverse micelles
作者:Marisa Bernardo、Rita Pacheco、Maria Luísa M. Serralheiro、Amin Karmali
DOI:10.1016/j.molcatb.2013.03.016
日期:2013.9
kinetic constants for the transamidation reaction in hydroxamicacidssynthesis, were determined using substrates such as aliphatic, amino acid and aromatic amides and esters, in both media. In reverse micelles, Km values decreased 2–7 fold relatively to the free biocatalyst using as substrates acetamide, acrylamide, propionamide and glycinamide ethyl ester. We have concluded that overall the affinity of
Thermodynamics of Core Metal Replacement and Self-Assembly of Ca<sup>2+</sup> 15-Metallacrown-5
作者:Matteo Tegoni、Michele Furlotti、Manuel Tropiano、Choong Sun Lim、Vincent L. Pecoraro
DOI:10.1021/ic100315u
日期:2010.6.7
The equilibria for core Ca2+ replacement by Ln3+ in copper(II) 15-MC-5 complexes have been investigated using a series of visible spectrophotometric titrations of calcium(II) metallacrowns (CaII[15-MCCuII(N)(L)-5]}2+) with Ln3+ ions (H2L = pheha, (S)-α-phenylalaninehydroxamic acid, or trpha, (S)-α-tryptophanhydroxamic acid). These studies allowed the determination of the equilibrium constants for
为平衡核心的Ca 2+通过LN置换3+在铜(II)15-MC-5复合物已使用一系列的钙可见分光光度滴定(II)metallacrowns(的Ca研究II [15-MC的Cu II( N)(L) -5]} 2+)与Ln 3+离子(H 2 L = pheha,(S)-α-苯丙氨酸异羟肟酸或trpha,(S)-α-色氨酸异羟肟酸)。这些研究使得可以确定反应的平衡常数Ca II [15-MC Cu II(N)(L) -5]} 2+ + Ln3+ →Ln III [15-MC Cu II(N)(L) -5]} 3+ + Ca 2+在甲醇/水中9:1(Ln 3+ = La 3+,Gd 3+,Dy 3 +,Er 3+)或99:1(Ln 3+ = La 3+,Nd 3+,Gd 3+,Dy 3+,Er 3+,Yb 3+)。日志K这些反应随镧系元素(III)原子数的增加而降低,在甲醇/水9:1中范围从6
Enhanced Guest Affinity and Enantioselectivity through Variation of the Gd<sup>3+</sup>[15-Metallacrown-5] Side Chain
作者:Joseph T. Grant、Joseph Jankolovits、Vincent L. Pecoraro
DOI:10.1021/ic300110g
日期:2012.8.6
generated by their ligand sidechains. A thermodynamic study on Gd3+[15-metallacrown-5] hosts with ligands bearing phenyl sidechains containing 0, 1, and 2 methylene spacers (1-pgHA, 1-pheHA, 1-hpheHA, respectively) is presented to quantitatively assess how guest affinity and chiral selectivity can be enhanced through changes to the ligand sidechain. Guest binding affinity was measured with cyclic
研究了可逆结合客体的超分子宿主潜在的催化和分离应用。手性Ln 3+ [15-金属内酰胺-5]金属配体在其配体侧链产生的疏水腔中结合羧酸盐客体。钆的热力学研究3+ [15-metallacrown-5]与主机配体带有含0,1和2个亚甲基隔片(苯基侧链1- pgHA,1 -pheHA,1 -hpheHA,分别地)呈现给定量评估如何通过改变配体侧链来增强客体亲和力和手性选择性。使用二茂铁羧酸盐作为氧化还原探针,通过循环伏安法测量客体结合亲和力。ķ一羧酸二茂铁与1 -pgHA和1 -pheHA之间的值分别为4800±400 M –1和4400±700 M –1。用1 -hpheHA测得的结合亲和力显着增强,为12100±700 M –1,这是由于较长的侧链更完全地包裹了客体。用苯甲酸酯观察到类似的趋势。侧链还影响对映选择性,因为测得的K S / K R值高达2.2±0.6。依赖于侧链的客体结合支持高选择性Ln
Influencing the Size and Anion Selectivity of Dimeric Ln<sup>3+</sup>[15-Metallacrown-5] Compartments through Systematic Variation of the Host Side Chains and Central Metal
作者:Joseph Jankolovits、Choong-Sun Lim、Gellert Mezei、Jeff W. Kampf、Vincent L. Pecoraro
DOI:10.1021/ic202347j
日期:2012.4.16
Ln3+[15-metallacrown-5] compartmentsselectively recognize carboxylates through guest binding to host metal ions and intermolecular interactions with the phenyl side chains. A systematic study is presented on how the size, selectivity, and number of encapsulated guests in the dimeric containers is influenced by the Ln3+[15-metallacrownCu(II)-5] ligand side chain and central metal. Compartments of varying heights