Search results for "stereochemistry"
showing 10 items of 4831 documents
Reactivity Towards Acidic Protic Ligands of Cyclopalladated Di‐μ‐hydroxo Complexes
2008
The dinuclear hydroxo complexes [{Pd(μ-OH)(C∧N)}2] [C∧N = 2-(2-pyridyl)phenyl (Phpy) (I), 7,8-benzoquinolyl (Bzq) (II) and 2-(2-oxazolinyl)phenyl (Phox) (III)] react in a 1:2 molar ratio with a wide variety of protic electrophiles H(L∧L) bearing different sets of donor atoms (L∧L = O∧O or O∧N) to give the mononuclear neutral palladium(II) derivatives with the general formula [Pd(L∧L)(C∧N)] [O∧O = salicylaldehydate (sal) (1), acetylacetonate (acac) (2) and benzoylacetonate (bzac) (3); O∧N = N-phenylsalicylaldiminate (N-Phsal) (4), N-p-chlorophenylsalicylaldiminate (N-pClPhsal) (5), 2-pyrrolecarbaldeydate (2-pcal) (6), 8-hydroxyquinolinate (oxin) (7)]. Structural characterisation of complexes…
Ferromagnetic coupling in a one-dimensional molecular railroad copper(II) azido compound containing a defective double cubane motif.
2001
The compound [Cu2(bpm)2(N3)4]n (bpm = bis(pyrazol-1−yl)methane) shows three unique coordination modes (μ1,1-, μ1,1,1-, μ1,1,3-N3) and ferromagnetic interaction between the copper(II) ions. The structure of the compound exhibits a one-dimensional railroad polymer made up of repeating defective dicubane-type units linked by μ1,1,3-N3 bridges.
Copper Complexes with Sulfonamides Derivatives of Natural Amino Acids as Chemical Nucleases
2007
Three new coordination compounds have been prepared by reacting copper salts with sulfonamides derived from amino acids. Their molecular structures have been determined with the aid of single crystal X-ray diffraction. The copper cations are four-coordinated in all cases and the local environment is almost planar. Compound [Cu(ts-gly)(NH3)2]·H2O (1) crystallizes in monoclinic space group P21/c (no 14) with Z = 4 and with unit cell parameters a = 6.0490(12) A, b = 24.719(5) A, c = 9.159(2) A, α = γ = 90°, and β = 94.69(3)°. Compound [Cu(ts-isoleu)(NH3)2] (2) crystallizes in monoclinic space group C2/c (no 8) with Z = 15 and with unit cell parameters a = 30.800(6) A, b = 6.5510(13) A, c = 15.…
Efficient Self-Assembly of Di-, Tri-, Tetra-, and Hexavalent Hosts with Predefined Geometries for the Investigation of Multivalency
2015
Coordination-driven self-assembly of differently shaped di- to hexavalent crown-ether host molecules is described. A series of [21]crown-7- and [24]crown-8-substituted bipyridine and terpyridine ligands was synthetized in a "toolbox" approach. Subsequent coordination to 3d transition metal and ruthenium(II) ions provides an easy and fast access to host assemblies with variable valency and pre-defined orientations of the crown-ether moieties. Preliminary isothermal calorimetry (ITC) titrations provided promising results, which indicated the host complexes under study to be suitable for the future investigation of multivalent and cooperative binding. The hosts described herein will also be su…
ChemInform Abstract: Glycoside Synthesis via Electrophile-Induced Activation of N-Allyl Carbamates.
2010
Abstract O-Benzyl-, O-acyl-, N-acyl- and isopropylidene-protected glycosyl N-allylcarbamates, obtained from anomerically unprotected monosaccharides and allyl isocyanate, are activated by an electrophile-induced cyclisation and react with hydroxyl compounds to form the corresponding glycosides.
Synthesis and antiproliferative activity of 2'-O-allyl-1-beta-D-arabynofuranosyl-uracil, -cytosine and -adenine
1997
Abstract With the aim to design potential inhibitors of ribonucleotide reductase (RR), 2′-O-allyl-β-D-arabinofuranosyl-uracil ( 4 ), -cytosine ( 7 ) and -adenosine ( 10 ) were prepared and evaluated for their cytostatic activity against Molt4/C8, CEM and L1210 cell lines. Although our preliminary data do not allow to assess if RR is the intracellular target, the results point to differences in the (anti)metabolic behavior of these compounds. This study also offers a general synthesis of 2′-O-allyl-β-D-arabinofuranosyl nucleosides for potential applications in the preparation of 2′-O-allyl-β-D-oligoarabino nucleotides.
ChemInform Abstract: Total Synthesis of (+)-Greek Tobacco Lactone.
2015
An enantioselective, protecting-group-free, total synthesis of (+)-Greek tobacco lactone has been achieved by using an organocatalytic Mukaiyama–Michael reaction and a stereospecific oxa-Michael reaction as key steps.
Total Synthesis of (+)-Greek Tobacco Lactone
2014
An enantioselective, protecting-group-free, total synthesis of (+)-Greek tobacco lactone has been achieved by using an organocatalytic Mukaiyama–Michael reaction and a stereospecific oxa-Michael reaction as key steps.
Restricted rotation in unbridged sandwich complexes: rotational behavior of closo-[Co(eta 5-NC4H4)(C2B9H11)] derivatives.
2005
Rotation about the centroid/ metal/centroid axis in ferrocene is facile; the activation energy is 1-5 kcal mol - 1 . The structurally similar sandwich complexes derived from closo-[3-Co(η 5 -NC 4 H 4 )-1,2-C 2 B 9 H 1 1 ] (1) have a different rotational habit. In 1, the cis rotamer in which the pyrrolyl nitrogen atom bisects the carboranyl cluster atoms is 3.5 kcal mol - 1 more stable in energy than the rotamer that is second lowest in energy. This cis rotamer is wide, spanning 216°, and may be split into three rotamers of almost equal energy by substituting the N and the carboranyl carbon atoms adequately. To support this statement, closo-[3-Co(η 5 -NC 4 H 4 )-1,2-(CH 3 ) 2 -1,2-C 2 B 9 H …
Synthesis, crystal structures and magnetic properties of M(II)Cu(II) chains (M = Mn and Co) with sterically hindered alkyl-substituted phenyloxamate …
2011
A series of neutral oxamato-bridged heterobimetallic chains of general formula [MCu(L(x)2 (S)2] · p S · q H2O [p = 0-1, q = 0-2.5; L1 = N-2,6-dimethylphenyloxamate, S = DMF with M = Mn (1a) and Co (1b); L2 = N-2,6-diethylphenyloxamate, S = DMF with M = Mn (2a) and Co (2b) or S = DMSO with M = Mn (2c) and Co (2 d); L3 = N-2,6-diisopropylphenyloxamate, S = DMF with M = Mn (3a) and Co (3b) or S = DMSO with M = Mn (3c) and Co (3d)] were prepared by treating the corresponding anionic oxamatocopper(II) complexes [Cu(L(x))(2)]2- (x = 1-3) with M(2+) cations (M = Mn and Co) in DMF or DMSO as the solvent. The single-crystal X-ray structures of 2a and 3a reveal the occurrence of well-isolated, zigzag…