Truncated Nucleosides as A3 Adenosine Receptor Ligands: Combined 2-Arylethynyl and Bicyclohexane Substitutions
摘要:
C2-Arylethynyladenosine-5'-N-methyluronamides containing a bicyclo[3.1.0]hexane [(N)-methanocarba] ring are selective A(3) adenosine receptor (AR) agonists. Similar 4'-truncated C2-arylethynyl-(N)-methanocarba nucleosides containing alkyl or alkylaryl groups at the N-6 position were low-efficacy agonists or antagonists of the human A(3)AR with high selectivity. Higher hA(3)AR affinity was associated with N-6-methyl and ethyl (K-i = 3-6 nM) than with N-6-arylallcyl groups. However, combined C2-phenylethynyl and N-6-2-phenylethyl substitutions in selective antagonist 15 provided a K-i of 20 nM. Differences between 4'-truncated and nontruncated analogues of extended C2-p-biphenylethynyl substitution suggested a ligand reorientation in AR binding, dominated by bulky N-6 groups in analogues lacking a stabilizing S'-uronamide moiety. Thus, 4'-truncation of C2-arylethynyl-(N)-methanocarba adenosine derivatives is compatible with general preservation of A(3)AR selectivity, especially with small N-6 groups, but reduced efficacy in A(3)AR-induced inhibition of adenylate cyclase.
Silylative reduction of nitriles was studied under transition metal-free conditions by using B(C6F5)3 as a catalyst with hydrosilanes as a reductant. Alkyl and (hetero)aryl nitriles were efficiently converted to primaryamines or imines under mild conditions. The choice of silanes was found to determine the selectivity: while a full reduction of nitriles was highly facile, the use of sterically bulky
在无过渡金属的条件下,通过使用B(C 6 F 5)3作为催化剂,以氢硅烷作为还原剂,研究了腈的甲硅烷基化还原反应。在温和的条件下,烷基和(杂)芳基腈被有效地转化为伯胺或亚胺。发现硅烷的选择决定了选择性:虽然腈的完全还原非常容易,但是使用空间大体积的硅烷允许部分还原,从而生成N-甲硅烷基亚胺。
Hydrogenation of Nitriles and Ketones Catalyzed by an Air-Stable Bisphosphine Mn(I) Complex
作者:Stefan Weber、Berthold Stöger、Karl Kirchner
DOI:10.1021/acs.orglett.8b03132
日期:2018.11.16
Efficient hydrogenations of nitriles and ketones with molecular hydrogen catalyzed by a well-defined bench-stable bisphosphine Mn(I) complex are described. These reactions are environmentally benign and atomically economic, implementing an inexpensive, earth-abundant nonprecious metal catalyst. A range of aromatic and aliphatic nitriles and ketones were efficiently converted into primary amines and
Old Concepts, New Application – Additive‐Free Hydrogenation of Nitriles Catalyzed by an Air Stable Alkyl Mn(I) Complex
作者:Stefan Weber、Luis F. Veiros、Karl Kirchner
DOI:10.1002/adsc.201901040
日期:2019.12.3
additive-free manganese-catalyzed hydrogenation of nitriles to primary amines with molecular hydrogen is described. The pre-catalyst, a well-defined bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dpre)(CO)3(CH3)] (dpre=1,2-bis(di-n-propylphosphino)ethane), undergoes CO migratory insertion into the manganese-alkyl bond to form acyl complexes which upon hydrogenolysis yields the active coordinatively
Synthesis, Characterization, and Catalytic Reactivity of {CoNO}<sup>8</sup> PCP Pincer Complexes
作者:Jan Pecak、Wolfgang Eder、Berthold Stöger、Sara Realista、Paulo N. Martinho、Maria José Calhorda、Wolfgang Linert、Karl Kirchner
DOI:10.1021/acs.organomet.0c00167
日期:2020.7.27
reaction of coordinatively unsaturated Co(II) PCP pincer complexes with nitric oxide leads to the formation of new, air-stable, diamagnetic mono nitrosylcompounds. The synthesis and characterization of five- and four-coordinate Co(III) and Co(I) nitrosyl pincer complexes based on three different ligand scaffolds is described. Passing NO through a solution of [Co(PCPNMe-iPr)Cl], [Co(PCPO-iPr)Cl] or
配位不饱和的Co(II)PCP钳形配合物与一氧化氮的反应导致形成新的,空气稳定的,抗磁性的单亚硝酰基化合物。描述了基于三种不同配体支架的五坐标和四坐标的Co(III)和Co(I)亚硝酰基钳夹配合物的合成和表征。使NO通过[Co(PCP NMe - i Pr)Cl],[Co(PCP O - i Pr)Cl]或[Co(PCP CH2 - i Pr)Br]溶液导致低自旋形成具有强烈弯曲的NO配体的复合物[Co(PCP- i Pr)(NO)X]。用(X = Cl,Br)AgBF 4处理后一种导致氯化物的提取和形成[Co(PCP- i Pr)(NO)] +类型的带有线性NO基团的阳离子方平面Co(I)配合物。如果将NO计为NO +,则该反应可被视为是金属中心被NO从自由基从Co(III)还原为Co(I)的形式上的两个电子还原。因此,根据Enemark–Feltham约定,这些系统可以描述为CoNO}
Reusable Nickel Nanoparticles‐Catalyzed Reductive Amination for Selective Synthesis of Primary Amines
作者:Kathiravan Murugesan、Matthias Beller、Rajenahally V. Jagadeesh
DOI:10.1002/anie.201812100
日期:2019.4
The preparation of nickel nanoparticles as efficient reductive amination catalysts by pyrolysis of in situ generated Ni‐tartaric acid complex on silica is presented. The resulting stable and reusable Ni‐nanocatalyst enables the synthesis of functionalized and structurally diverse primary benzylic, heterocyclic and aliphatic amines starting from inexpensive and readily available carbonyl compounds and