1,720,975 research outputs found
Bis-2-thienyldiethylaminophosphane as a Ligand in Late Transition Metal Complexes and its Transformation to Bis-2-thienylphosphane
No full textBis-2-thienyldiethylaminophosphane (C4H3S)(2)PNEt2 (1) is introduced as a ligand for late transition metal complexes ([(H3C4S)(2)PNEt2](n)MXmLp), with M = Ni(II), An(I), Cu(I), Pd(II), Ir(I), X = Cl, Br and L = NCMe, COD, (2-7). Reactions of 1 with the late transition metal salts NiC12.dme, (Me2S)AuCl, CuCI, PdCl2(PhCN)(2), and [Ir(COD)Cl](2) yield the complexes [{(H3C4S)(2)PNEt2}(2). NiCl2] (2), [(H3C4S)(2)PNEt2.AuCl] (3) [(H3C4S)(2)PNEt2.IrCl(CH3 CN)(2) (4), [{(H3C4S)(2)PNEt2}(2) PdCl2] (5), [(H3C4S)(2)PNEt2}(2).PdCl2}(2) (6), and [(H3C4S)(2)PNEt2.IrCl(COD)] (7). In addition, the transformation of 1 to the valuable chlorine-substituted starting material (H3C4S)(2)PCl (8) and the related conversion of 8 to the secondary phosphane (H3C4S)(2)PH (9) is reported. The complexes 2-7 are stable under inert gas conditions and were characterized by single-crystal X-ray studies, NMR spectroscopy, and elemental analysis.DNRF [DNRF93]; Land Niedersachse
Concise Synthesis and X-Ray Crystal Structure of N-Benzyl-2-(pyrimidin-4-ylamino)-thiazole-4-carboxamide (Thiazovivin), a Small-Molecule Tool for Stem Cell Research
No full textStem cell research is one of the most promising fields of modern biomedical research and regenerative medicine. Limited availability and ethical concerns suggest the renouncement of embryonic stem cells (ESCs), thus raising the need for more efficient procedures for the generation of stem cells, ideally through reprogramming of mammalian cells. The small molecule N-benzyl-2-(pyrimidin-4-ylamino)-thiazole-4-carboxamide (thiazovivin) is known to improve the generation of human induced pluripotent stem cells (iPSCs) from human fibroblasts. We herein describe a highly efficient procedure for the synthesis of thiazovivin over just five steps, which should be suitable for a large-scale application, and the first x-ray crystal structure of the target compound. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) for the following free supplemental resource: Full experimental and spectral details.
Polymorphism of Dibromo-tetrakis(tetrahydrofuran-kappa O)magnesium(II)
No full textThe title compound, [MgBr(2)(C(4)H(8)O)(4)] (1a), forms twinned four-component monoclinic crystals as a new polymorph, space group P2(l)/n with Z' = 2, in addition to the already known tetragonal polymorph (1b). Although the molecular parameters in the two polymorphs match very well, the packing patterns are significantly different. Furthermore, the correct constitution of the mixed halide bromo-chloro-tetrakis(tetrahydrofuran-kappa O)magnesium(II) (2) could be determined
Polymorphism of Dibromo-tetrakis(tetrahydrofuran-kappa O)magnesium(II)
No full textThe title compound, [MgBr(2)(C(4)H(8)O)(4)] (1a), forms twinned four-component monoclinic crystals as a new polymorph, space group P2(l)/n with Z' = 2, in addition to the already known tetragonal polymorph (1b). Although the molecular parameters in the two polymorphs match very well, the packing patterns are significantly different. Furthermore, the correct constitution of the mixed halide bromo-chloro-tetrakis(tetrahydrofuran-kappa O)magnesium(II) (2) could be determined
A biomimetic domino reaction for the concise synthesis of capreomycidine and epicapreomycidine
No full textThe non-proteinogenic amino acids capreomycidine and epicapreomycidine are constituents of antibiotically active natural products, but the synthesis of these unusual cyclic guanidine derivatives is challenging. The biosynthesis of capreomycidine has therefore been employed as a guideline to develop a concise biomimetic synthesis of both epimeric amino acids. The resulting domino-guanidinylation-aza-Michael-addition reaction provides the most convenient access to these amino acids in racemic form. Attempts to dissect the domino reaction into two separate transformations for a stereocontrolled version of this synthetic approach have also been made. The synthesized didehydro-arginine derivatives with urethane-protected guanidine moieties did not undergo the aza-Michael-addition anymore. These results may have wider implications for the 1,4-addition of guanidines to alpha,beta-unsaturated carbonyl compounds, particularly to didehydro amino acids
Reducing the conformational flexibility of carbohydrates: locking the 6-hydroxyl group by cyclopropanes
No full textThe 6-hydroxyl group of hexopyranosides was stereochemically locked by the spiroannelation of a cyclopropane unit at C-5. The corresponding glucose and mannose derivatives were prepared and their behaviour in glycosidation reactions was studied.Deutsche Forschungsgemeinschaft; Fonds der Chemischen Industrie; DNR
N-Heterocyclic Carbene Stabilized Dichlorosilaimine IPr·Cl<sub>2</sub>Si═NR
No full textN-Heterocyclic carbene stabilized dichlorosilaimine IPr center dot Cl2Si=N(Diip) (2) has been synthesized by the reaction of dichlorosilylene IPr center dot SiCl2 (1) with bis(2,6-diisopropylphenyl)carbodiimide (IPr = :C[N(2,6-i-Pr-2-C6H3)CH](2), Diip = 2,6-i-Pr-2-C6H3). Reaction of 1 with terphenyl azides also affords dichlorosilaimines IPr center dot Cl2Si=N(2,6-Diip(2)-C6H3) (3) and IPr center dot Cl2Si=N(2,6-Triip(2)-C6H3) (4) (Triip = 2,4,6-i-Pr-3-C6H2). Compounds 2-4 are stable under an inert atmosphere and were characterized by elemental analysis and NMR spectroscopic studies. The molecular structures of 2-4 were determined by single-crystal X-ray analysis.Deutsche Forschungsgemeinschaf
Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine
No full text(2S,3S)-3-Hydroxyleucine can be found in an increasing number of bioactive natural products. Within the context of our work regarding the total synthesis of muraymycin nucleoside antibiotics, we have developed a synthetic approach towards (2S,3S)-3-hydroxyleucine building blocks. Application of different protecting group patterns led to building blocks suitable for C- or N-terminal derivatization as well as for solid-phase peptide synthesis. With respect to according motifs occurring in natural products, we have converted these building blocks into 3-O-acylated structures. Utilizing an esterification and cross-metathesis protocol, (2S,3S)-3-hydroxyleucine derivatives were synthesized, thus opening up an excellent approach for the synthesis of bioactive natural products and derivatives thereof for structure activity relationship (SAR) studies
ChemInform Abstract: Reducing the Conformational Flexibility of Carbohydrates: Locking the 6‐Hydroxyl Group by Cyclopropanes.
No full textA Facile Route to Functionalized N-Heterocyclic Carbenes (NHCs) with NHC Base-Stabilized Dichlorosilylene
No full textReaction of IPr.SiCl2 (1) [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] with 1-azidoadamantane leads to functionalized N-heterocyclic carbene (NHC) 2. Silyl-substituted NHC 2 reacts easily with 1-azidoadamantane to form triazene 3, in which the exocyclic C=N bond is slightly shorter than those of regular NHC-derived triazines. 2 could serve as a promising ligand for transition metals.Deutsche Forschungsgemeinschaft (DFG
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