- Synthesis of amidoalkyl imidazol-2-ylidene ligands and their application to enantioselective copper-catalysed conjugate addition
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A small library of precursors to chiral amidoalkyl imidazol-2-ylidene ligand was synthesised via a two-step procedure starting from commercially available amino alcohols. Preliminary screening of these bidentate ligands for the enantioselective copper-catalysed conjugate addition of diethyl zinc to cyclohexenone revealed some moderate ee values. Related chiral iminoalkyl imidazole-2-ylidene ligands demonstrated much poorer enantioselectivity. The results indicate that chelation involving a covalent copper-nitrogen bond gives better selectivity than that arising from a dative copper-nitrogen co-ordination. Georg Thieme Verlag Stuttgart.
- Moore, Theo,Merzouk, Mahboub,Williams, Neil
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- Synthesis of chiral iminoalkyl functionalised N-heterocyclic carbenes and their use in asymmetric catalysis
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A library of new chiral iminoalkyl imidazolium salts has been synthesised from amino acids using a modular design approach. Deprotonation with silver oxide yields silver carbene transfer reagents, which can be used as ligand sources in asymmetric catalysis. Preliminary testing has shown that the ligands induce enantioselectivity in the palladium-catalysed allylic alkylation of 1,3-diphenylprop-3-enyl acetate with dimethyl malonate.
- Merzouk, Mahboub,Moore, Theo,Williams, Neil A.
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p. 8914 - 8917
(2008/03/14)
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- Synthesis and properties of novel chiral-amine-functionalized ionic liquids
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A novel class of chiral-amine-functionalized ionic liquids (CAFILs) has been synthesized efficiently from natural amino acids, and their structures have been determined by spectroscopic analysis and low temperature X-ray diffraction analysis. The CAFILs have been characterized by physical properties such as melting point, glass transition temperature, thermal degradation and specific rotation. NMR measurements indicate that the CAFILs may be promising alternatives in the field of chiral discrimination.
- Luo, Shu-Ping,Xu, Dan-Qian,Yue, Hua-Dong,Wang, Li-Ping,Yang, Wen-Long,Xu, Zhen-Yuan
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p. 2028 - 2033
(2007/10/03)
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- Properties and Reactions of Substituted 1,2-Thiazetidine 1,1-Dioxides: Chiral Mono- and Bicyclic 1,2-Thiazetidine 1,1-Dioxides from α-Amino Acids
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New chiral mono- and bicyclic β-sultams, valuable building blocks for drug synthesis, have been prepared from L-Ala, L-Val, L-Leu, L-Ile, L-Phe, L-Cys, L-Ser, L-Thr, and D-penicillamine by transformation of the COOH group into a methylsulfonyl chloride function, followed by cyclization under basic conditions. Selected properties, derivatives, and reactions of the β-sultams are described.
- Meinzer, Alexandra,Breckel, Andrea,Thaher, Bassam Abu,Manicone, Nico,Otto, Hans-Hartwig
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- Stereochemistry and Reactions of Aziridinylphosphinothionates Derived from Amino Acids
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Aziridinylphosphinothionates were prepared from optically active ethyl hydrogen phenylphosphonothionates and 1-bromo-2-alkanamines derived from leucine or valine.The aziridine ring was opened by the action of some nucleophiles.Refluxing the aziridinylphosphinethionates in acetone with sodium iodide caused hydrolysis accompanied by the rearrangement of the sulfur atom to give β-mercaptoethylphosphonamidates.The reaction mechanism was discussed eith stereochemical considerations.The insecticidal activity of the products was also examined.
- Hirashima, Akinori,Eto, Morifusa
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p. 829 - 838
(2007/10/02)
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