US EPA

2325016 

Journal Article 

Asymmetric Allylation of Ketones and Subsequent Tandem Reactions Catalyzed by a Novel Polymer-Supported Titanium-BINOLate Complex 

Yadav, J; Stanton, GR; Fan, X; Robinson, JR; Schelter, EJ; Walsh, PJ; Pericas, MA 

2014 

Yes 

Chemistry: A European Journal
ISSN: 0947-6539
EISSN: 1521-3765 

20 

23 

7122-7127 

English 

24737394 

10.1002/chem.201400204 

By using a novel, simple, and convenient synthetic route, enantiopure 6-ethynyl-BINOL (BINOL=1,1-binaphthol) was synthesized and anchored to an azidomethylpolystyrene resin through a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The polystyrene (PS)-supported BINOL ligand was converted into its diisopropoxytitanium derivative in situ and used as a heterogeneous catalyst in the asymmetric allylation of ketones. The catalyst showed good activity and excellent enantioselectivity, typically matching the results obtained in the corresponding homogeneous reaction. The allylation reaction mixture could be submitted to epoxidation by simple treatment with tert-butyl hydroperoxide (TBHP), and the tandem asymmetric allylation epoxidation process led to a highly enantioenriched epoxy alcohol with two adjacent quaternary centers as a single diastereomer. A tandem asymmetric allylation/Pauson-Khand reaction was also performed, involving simple treatment of the allylation reaction mixture with Co2 (CO)8 /N-methyl morpholine N-oxide. This cascade process resulted in the formation of two diastereomeric tricyclic enones in high yields and enantioselectivities.