Enantioselective epoxidation of non-functionalised alkenes using a urea–hydrogen peroxide oxidant and a dimeric homochiral Mn(III)-Schiff base complex catalyst
2001; Elsevier BV; Volume: 12; Issue: 3 Linguagem: Inglês
10.1016/s0957-4166(01)00057-x
ISSN1362-511X
AutoresRukhsana I. Kureshy, Noor‐ul H. Khan, Sayed H. R. Abdi, Sunil T. Patel, Raksh V. Jasra,
Tópico(s)Oxidative Organic Chemistry Reactions
ResumoThe catalytic enantioselective epoxidation of chromenes, indene and styrene using a urea–hydrogen peroxide adduct as an oxidising agent and the novel dimeric homochiral Mn(III)-Schiff base catalyst 1 has been investigated in the presence of carboxylate salts and nitrogen and oxygen coordinating co-catalysts. Conversions of more than 99% were obtained with all alkenes except styrene. Absolute chiral induction, as determined by 1H NMR using the chiral shift reagent (+)-Eu(hfc)3, was obtained in the case of nitro- and cyanochromene. The catalyst could be re-used for up to five cycles with some loss of activity due to degradation of the catalyst under epoxidation condition with retention of e.e.'s.
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