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Asymmetric epoxidat...
Asymmetric epoxidation of styrene and chromenes catalysed by dimeric chiral (pyrrolidine salen)Mn(III) complexes
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Wang, Dongping (författare)
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Wang, Mei (författare)
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Zhang, Rong (författare)
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Wang, Xiuna (författare)
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Gao, Aiping (författare)
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Ma, Jia (författare)
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- Sun, Licheng (författare)
- KTH,Organisk kemi
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(creator_code:org_t)
- Elsevier BV, 2006
- 2006
- Engelska.
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Ingår i: Applied Catalysis A. - : Elsevier BV. - 0926-860X .- 1873-3875. ; 315, s. 120-127
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Two dimeric chiral (pyrrolidine salen)Mn(III) complexes 3 and 4 were prepared, in which the two (pyrrolidine salen)Mn(III) units are linked either by a p-xylylene or by ap-phthalyl bridge. High yields were attained for asymmetric epoxidation of styrene and substituted chromenes at 0.5-4.0 mol% catalyst loading of 3 and 4 using NaClO/PPNO and m-CPBA/NMO as oxidant systems, with 37-39% ee for styrene and 86-95% ee for substituted chromenes. Dimeric complexes 3 and 4 displayed higher activities than their parent monomeric complexes 1 and 2 of double equiv for epoxidation of substituted chromenes. Complex 3 bearing two tertiary amine units displayed considerably higher activity than analogous dimeric complex 4 containing two carboxamide units in the aforementioned reaction. The effect of excess CH3I on the epoxidation of 6-nitro-2,2-dimethylchromene catalysed by 3 in the aqueous/organic biphasic medium was explored. The recovery and recycling possibilities of the dimeric complexes 3 and 4 were studied.
Nyckelord
- asymmetric epoxidation
- chromene
- dimeric manganese complex
- salen ligand
- styrene
- highly enantioselective epoxidation
- phase-transfer capability
- nonfunctionalized alkenes
- unfunctionalised olefins
- salen complexes
- epoxides
- oxidant
- silica
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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