Asymmetric Allylation of Ketones and Subsequent Tandem Reactions Catalyzed by a Novel Polymer‐Supported Titanium–BINOLate Complex1. Issue 23 (15th April 2014)

• Record Type: Journal Article
• Authors: Yadav, Jagjit; Stanton, Gretchen R.; Fan, Xinyuan; Robinson, Jerome R.; Schelter, Eric J.; Walsh, Patrick J.; Pericas, Miquel A.
• Is Part Of: Chemistry. Volume 20:Issue 23(2014)
• Page Start: 7122
• Page End: 7127
• Publication Date: 2014-04-15
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201400204
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>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 <italic>tert</italic>‐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/<italic>N</italic>‐methyl morpholine <italic>N</italic>‐oxide. This cascade process resulted in the formation of two diastereomeric tricyclic enones in high yields and enantioselectivities.</p> </abstract>