Über die Struktur der Thioamide und ihrer Derivate, XIII<sup>1)</sup> Konfiguration monosubstituierter Thioharnstoffe

Walter, Wolfgang; Ruess, Klaus-Peter

doi:10.1002/jlac.19717430117

Cited by 35 publications

(6 citation statements)

References 13 publications

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“…The preparation of the required carbene 3 commences with the reaction between methyl isothiocyanate and 2, 6‐diisopropylaniline, which afforded thiourea 1 according to a modified literature procedure 9. Treatment of 1 with 3‐hydroxybutanone in 1‐hexanol gave the imidazolin‐2‐thione 2 in satisfactory yield (65 %, Scheme ) 10.…”

Section: Resultsmentioning

confidence: 99%

Transition Metal Complexes Containing C₂‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene

Glöge

Aal

Filimon

et al. 2015

Zeitschrift anorg allge chemie

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The new N-heterocyclic carbene 1-(2,6-diisopropylphenyl)-3,4,5-trimethylimidazolin-2-ylidene (IPrMe) (3) was prepared in three steps from methyl isothiocyanate and 2,6-diisopropylaniline, affording N-methyl-NЈ-2,6-diisopropylthiourea (1). Reaction of 1 with 3-hydroxybutanone gave the imidazolin-2-thione (IPrMe)S (2), which was reduced with elemental potassium to the carbene IPrMe (3). Treatment of 3 with trimethylsilyl azide (Me 3 SiN 3 ) in boiling toluene, followed by desilylation in methanol, gave the imidazolin-2-imine (IPrMe)NH (4). The ethylene-bridged diimine ligand N, diisoprop-* Prof. Dr. M. Tamm 2204 ylphenyl)-3,4,5-trimethylimidazolin-2-ylidene]-1,2-ethanediamine, (IPrMe)NCH 2 CH 2 N(IPrMe) (5) was prepared by reaction of 4 with 1,2-ethyleneditosylate and subsequent deprotonation with KOtBu. The reaction of 5 with metal dichlorides furnished the tetrahedral complexes [(5)MCl 2 ] [M = Fe (6), M = Ni (7), M = Zn (8)] and the squareplanar complex [(5)PdCl 2 ] (9), as revealed by X-ray diffraction analyses. The X-ray crystal structures of 2, 3, and 4 were also established. Complex 8 and related zinc(II) bis(imidazolin-2-imine) complexes were tested in the polymerization of d,l-lactide.the ligands BL R,RЈ (Scheme 1), with the contribution of the dipolar mesomeric form increasing significantly upon coordination to transition metal complex fragments. As a conse-Scheme 1. Mesomeric structures (A, B) for bis(imidazolin-2-imine) ligands BL R,RЈ (BL Me : R = RЈ = Me; BL iPr : R = RЈ = iPr; BL Dipp,Me : R = 2,6-diisopropylphenyl, RЈ = Me); schematic presentation of C 2symmetric bis(imidazolin-2-imine) metal complexes (box). Journal of Inorganic and General Chemistry Zeitschrift für anorganische und allgemeine Chemie www.zaac.wiley-vch.de ARTICLE Dedicated Clusterquence of this charge separation, the imidazole rings in the resulting metal complexes usually adopt a perpendicular orientation relative to the N-M-N plane, precluding any significant π-interaction with the metal-bound nitrogen atoms.Accordingly, bis(imidazolin-2-imine) ligands with a symmetric N,NЈ-substitution pattern (R = RЈ), such as BL Me and BL iPr , usually form C s -or C 2v -symmetric chelate complexes with four magnetically equivalent nitrogen substituents. [1] The introduction of unsymmetric imidazolin-2-ylidene moieties with nitrogen substituents of distinctly different size, however, might afford BL R,R' ligands (R = BIG ϶ RЈ = small) that are able to form chiral C 2 -symmetric complexes by adopting a conformationally stable anti-orientation of the R and RЈ pairs of substituents as illustrated in Scheme 1 (box). In principle, this would allow the synthesis of chiral complexes for applications in asymmetric catalysis such as transfer hydrogenation. [4c,4f,4g] A similar concept was developed for related αdiimine ligands and their respective nickel(II) and palladium(II) complexes, which serve as catalysts for the production of highly branched polyethylene. [6] To test this hypothesis, we report herein the preparation of the bis(imidazolin-2-im...

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Section: Resultsmentioning

confidence: 99%

Transition Metal Complexes Containing C₂‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene

Glöge

Aal

Filimon

et al. 2015

Zeitschrift anorg allge chemie

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“…Based on a structural analogy to amsacrine we suppose that our compounds could also participate in the electron transfer reactions with DNA. Though acridinium dithioureas can theoretically adopt a thione or thiol tautomeric structure [35], the latter can be reliably excluded according to an energy calculation [36]. Therefore, a possible factor for electron transfer reactions of our compounds might be sought in the interaction of DNA with the thiourea systems conjugated with the charged acridine -orbital (Scheme 2).…”

Section: Cytotoxic Effect On Human Leukemia Cellsmentioning

confidence: 99%

Cytotoxic activity of acridin-3,6-diyl dithiourea hydrochlorides in human leukemia line HL-60 and resistant subline HL-60/ADR

Vantová

Paulíková

Sabolová³

et al. 2009

International Journal of Biological Macromolecules

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“…The chemical shifts in 21, for example, point to a significant magnetic anisotropy of the thiocarbonyl group. [50,51] X-ray crystallography of the trans-4-tert-butylcyclohexyloxy-substituted pyridinethione 34 ( Figure 6) shows a CϪS distance of 1.668(4) Å , which is in the typical range for the thioamide functionality. [50] The NϪO bond length in 34 is 1.384(4) Å .…”

Section: Preparation and Properties Of Thiohydroxamatederived O-radicmentioning

confidence: 99%

Stereoselective Construction of the Tetrahydrofuran Nucleus by Alkoxyl Radical Cyclizations

Hartung¹

2001

Eur. J. Org. Chem.

139

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Whereas carbon radical cyclizations have been applied for many years in the stereoselective synthesis of carbocyclic compounds, intramolecular C−O bond formations using alkoxyl radical reactions are less well understood. Since the discovery of N‐alkoxypyridine‐2(1H)‐thiones 8 as efficient sources of oxygen‐centered radicals, and the marked progress in the synthesis of these and related compounds which has been made in the last five years, however, a systematic study of O‐radical cyclizations under neutral conditions has become available. Kinetic experiments using the radical clock technique found that the parent 4‐penten‐1‐oxyl radical 1 undergoes an extremely fast 5‐exo‐trig ring‐closure [(4 ± 2) × 108 s−1 (30 °C)] which, after hydrogen trapping, selectively affords 2‐methyltetrahydrofuran (50). Tetrahydropyran (56), which originates from the slower 6‐endo‐trig cyclization, was observed in minor amounts. This observation pointed to a more diverse regioselectivity of O‐radicals in intramolecular addition reactions to olefinic double bonds than had been predicted from earlier experiments. A mechanistic study of ring‐closure reactions of the substituted 4‐penten‐1‐oxyl radicals 51 led to two major conclusions. Firstly, 1‐, 2‐, 3‐, and 5‐substituted radicals cyclize stereoselectively and 5‐exo‐trig‐regioselectively. The degree of stereoselectivity is governed by steric effects. To date, the only exceptions to this rule remain cyclizations of the para‐substituted 1‐aryl‐4‐penten‐1‐oxyl radicals 51e−m. These intermediates cyclize regioselectively, but not stereoselectively. Secondly, substituents at position 4 of the 4‐penten‐1‐oxyl radical are the key for controlling regioselectivities in O‐radical ring‐closure reactions. Thus, the 4‐phenyl‐4‐penten‐1‐oxyl radical 51u cyclizes 6‐endo‐trig‐selectively to afford, after hydrogen trapping, 2‐phenyltetrahydropyran (59u) as the major product (5‐exo:6‐endo = 5:95). Results from mechanistic and theoretical studies have been combined in order to derive a general model for predicting alkoxyl radical selectivities in ring closure reactions. The utility of this predictive device has recently been confirmed in the course of a new stereoselective synthesis of the central ring in muscarine alkaloid 72.

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Über die Struktur der Thioamide und ihrer Derivate, XIII¹⁾ Konfiguration monosubstituierter Thioharnstoffe

Cited by 35 publications

References 13 publications

Transition Metal Complexes Containing C₂‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene

Transition Metal Complexes Containing C₂‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene

Cytotoxic activity of acridin-3,6-diyl dithiourea hydrochlorides in human leukemia line HL-60 and resistant subline HL-60/ADR

Stereoselective Construction of the Tetrahydrofuran Nucleus by Alkoxyl Radical Cyclizations

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Über die Struktur der Thioamide und ihrer Derivate, XIII1) Konfiguration monosubstituierter Thioharnstoffe

Cited by 35 publications

References 13 publications

Transition Metal Complexes Containing C2‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene

Transition Metal Complexes Containing C2‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene

Cytotoxic activity of acridin-3,6-diyl dithiourea hydrochlorides in human leukemia line HL-60 and resistant subline HL-60/ADR

Stereoselective Construction of the Tetrahydrofuran Nucleus by Alkoxyl Radical Cyclizations

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Über die Struktur der Thioamide und ihrer Derivate, XIII¹⁾ Konfiguration monosubstituierter Thioharnstoffe

Transition Metal Complexes Containing C₂‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene

Transition Metal Complexes Containing C₂‐Symmetric Bis(imidazolin‐2‐imine) Ligands Derived from a 1‐Alkyl‐3‐arylimidazolin‐2‐ylidene