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Synthesis of heterocyclic carbene ligands via 1,2,3-diheterocyclization of allenylidene complexes with dinucleophiles

Synthesis of heterocyclic carbene ligands via 1,2,3-diheterocyclization of allenylidene complexes with dinucleophiles

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SZESNI, Normen, Christiane HOHBERGER, Gehad Genidy MOHAMED, Nicolai BURZLAFF, Bernhard WEIBERT, Helmut FISCHER, 2006. Synthesis of heterocyclic carbene ligands via 1,2,3-diheterocyclization of allenylidene complexes with dinucleophiles. In: Journal of Organometallic Chemistry. 691(26), pp. 5753-5766. ISSN 0022-328X

@article{Szesni2006Synth-22892, title={Synthesis of heterocyclic carbene ligands via 1,2,3-diheterocyclization of allenylidene complexes with dinucleophiles}, year={2006}, doi={10.1016/j.jorganchem.2006.07.049}, number={26}, volume={691}, issn={0022-328X}, journal={Journal of Organometallic Chemistry}, pages={5753--5766}, author={Szesni, Normen and Hohberger, Christiane and Mohamed, Gehad Genidy and Burzlaff, Nicolai and Weibert, Bernhard and Fischer, Helmut} }

Mohamed, Gehad Genidy Hohberger, Christiane Hohberger, Christiane deposit-license 2013-05-31T17:01:01Z Szesni, Normen Fischer, Helmut Synthesis of heterocyclic carbene ligands via 1,2,3-diheterocyclization of allenylidene complexes with dinucleophiles Burzlaff, Nicolai Fischer, Helmut eng Journal of Organometallic Chemistry, 691 (2006), 26. - S. 5753-5766 Burzlaff, Nicolai 2006 Szesni, Normen 2013-05-31T17:01:01Z Weibert, Bernhard Heterocyclic carbene complexes are accessible from p-donor-substituted allenylidene complexes, [(CO)<sub>5</sub>Cr=C=C=C(NMe<sub>2</sub>)Ph] (1) and [(CO)<sub>5</sub>Cr=C=C=C(O-endo-Bornyl)OEt] (4), and various dinucleophiles by 1,2,3-diheterocyclization. The reaction of 1 with 1,2-dimethylhydrazine gives the 1,2-dimethylpyrazolylidene complex [(CO)<sub>5</sub>Cr=C-C(H)=C(Ph)-NMe-NMe] (2) in high yield in addition to small amounts of the a,b-unsaturated carbene complex [(CO)<sub>5</sub>Cr=C(NMe<sub>2</sub>)–C(H)=C(NMe<sub>2</sub>)Ph] (3). The analogous reaction of 4 with 1,2-dimethylhydrazine affords the 1,2-dimethylpyrazolylidene complex [(CO)<sub>5</sub>Cr=C-C(H)=C(O-endo-Bornyl)-NMe-NMe] (5) and, via displacement of the Cc-bound ethoxy substituent, the hydrazinoallenylidene complex [(CO)5Cr=C=C=C(O-endo-Bornyl){NMe-N(H)Me}] (6). Treatment of 6 with catalytic amounts of acids induces cyclization to 5. On addition of 1,1-dimethylhydrazine to 1 the zwitterionic pyrazolium-5-ylidene complex [(CO)<sub>5</sub>Cr-C=C(H)-C(Ph)=N-NMe<sub>2</sub>] (7) is formed. The reaction of 1 with 1,2-diaminocyclohexane affords a octahydro-benzo[1,4]diazepinylidene complex (10) and, via intermolecular substitution, a binuclear bisallenylidene complex (11). Thiazepinylidene complexes (12–14), containing 7-membered N/S-heterocyclic carbene ligands, are formed highly selectively in the reaction of 1 with 2-aminoethanethiol or related cysteine derivatives by a substitution/cyclization sequence. The analogous reaction of 1 with homocysteine methylester yields a thiazocanylidene complex (15). All new heterocyclic carbene ligands are strong donors exhibiting r-donor/ p-acceptor ratios similar to those of the known imidazolylidene complexes. On photolysis of 2 and 12 in the presence of triphenylphosphine, the corresponding cis-carbene tetracarbonyl triphenylphosphine complexes (16 and 17) are formed. The solid state structure of complexes 2, 7, 14, 15, and 16 is established by X-ray structural analysis Mohamed, Gehad Genidy Weibert, Bernhard

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