Chiral palladacycle promoted asymmetric synthesis of functionalized bis-phosphine monoxide ligand

An organopalladium complex containing orthometalated (R)-(1-(dimethylamino)ethyl)naphthalene as the chiral auxiliary has been used to promote the asymmetric hydroalkoxylation reactions between weak nucleophile methanol and 1,1-bis(diphenylphosphino)ethylene or 1,1-bis(diphenylphosphino)ethylene monoxide in good regio- and stereo-selectivities in the presence of an external base. The major addition product obtained from methanol and 1,1-bis(diphenylphosphino)ethylene monoxide was subsequently isolated in a quantitative yield in its configurationally pure form and characterized by means of two-dimensional rotating-frame nuclear Overhauser enhancement (ROESY) NMR spectroscopy as well as single crystal X-ray diffraction analysis. The enantiomerically pure bis-phosphine monoxide ligand was subsequently liberated in high yield.

Graphical abstractAsymmetric hydroalkoxylation of the coordinated 1,1-bis(diphenylphosphino)ethylene monoxide gave the addition products in high yields. The major isomer was subsequently isolated in a quantitative yield in its configurationally pure form and characterized by means of single crystal X-ray crystallography. The enantiomerically pure bis-phosphine monoxide ligand was subsequently liberated in high yield.Figure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights► Enantiomerically pure bis-phosphine monoxide ligand synthesis. ► Asymmetric hydroalkoxylation reactions of bis-phosphine and bis-phosphine monoxide ligands. ► Two synthetic pathways towards a chiral bis-phosphine monoxide via hydroalkoxylation reactions and selective oxidation reactions. ► Access to a range of pure functionalized bis-phosphine monoxide ligands.