Ethynylbenziodazolones (EBZ) as Electrophilic Alkynylation Reagents for the Highly Enantioselective Copper‐Catalyzed Oxyalkynylation of Diazo Compounds
radicals and nucleophiles, yet they present limited possibilities for further structure and reactivity modification. Herein, the first synthesis is reported for the corresponding ethynylbenziodazolone (EBZ) reagents, in which the oxygen atom in the iodoheterocycle is replaced by a nitrogen atom. The substituent on the nitrogen enables further fine‐tuning of the reagent structure and reactivity. EBZ reagents
A new method for recycling chiral bis(oxazoline)-coppercomplexes is described based on the formation of charge-transfercomplexes, their subsequent precipitation, and reuse after addition of new substrates. The conditions to perform this procedure were optimized in the presence of three bis(oxazoline)-based ligands. When associated with copper salts, these ligands efficiently catalyzed the Diels-Alder
Improved Enantioselectivity of Immobilized Chiral Bisoxazolines by Partial Precapping of the Siliceous Mesocellular Foam Support with Trimethylsilyl Groups
作者:Su Seong Lee、Sukandar Hadinoto、Jackie Y. Ying
DOI:10.1002/adsc.200606027
日期:2006.7
Siliceousmesocellularfoams (MCF) were partially surface-modified with trimethylsilyl (TMS) groups prior to the immobilization of chiral tert-butylbisoxazolines. The resulting MCF-supported bisoxazoline-Cu(I) catalyst showed superior enantioselectivity (up to 95 % ee) in asymmetric cyclopropanation, compared to that supported on MCF without TMS precapping. This heterogenized catalyst also exhibited
The present invention describes a heterogeneous chiral catalyst comprising a heterogeneous chiral catalyst precursor complexed with a metal species. The precursor comprises a chiral bisoxazoline group coupled to an inorganic substrate. The heterogeneous chiral catalyst may be capable of catalysing a chemical reaction, for example cyclopropanation, and the chemical reaction may be capable of generating a chiral product.