Evaluation of bifunctional chiral phosphine oxide catalysts for the asymmetric hydrosilylation of ketimines

• Published in: Tetrahedron 2019-12, Vol.75 (50), p.130733, Article 130733
• Main Authors: Warner, Christopher J.A., Berry, Sian S., Jones, Simon
• Format: Article
• Language: English
• Subjects: Asymmetric catalysis; Hydrosilylation; Organocatalysis; Phosphine oxide
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2019.130733

A series of bifunctional phosphine oxides have been prepared and evaluated as catalysts for the trichlorosilane mediated asymmetric hydrosilylation of ketimines. bis-Phosphine oxides, hydroxy-phosphine oxides, and biaryl phosphine oxides all demonstrated good catalytic activity, but poor to moderate enantioselectivity. A bis-P-chiral phosphine oxide displayed the highest enantioselectivity of 60%. [Display omitted] •A series of achiral and chiral, non-racemic bifunctional phosphine oxides have been prepared.•The target compounds were evaluated as catalysts in the hydrosilylation of a benchmark ketimine.•Almost all acted as very effective catalysts, although enantioselectivities were generally poor.•A bifunctional P-chiral catalyst gave the best enantioselectivity, helping to reinforce a dual activation model.