Novel Chiral Bisformamide-Promoted Asymmetric Allylation of Benzaldehyde with Allyltrichlorosilane

Abstract

Novel chiral bisformamides have been prepared from (R,R)-1,2-cyclohexanediamine and utilized as Lewis bases in the asymmetric allylation of benzaldehyde with allyltrichlorosilane. The reaction in the presence of Lewis base 1i gave an 83:17 enantiomeric ratio (R/S) of the products in 90% isolated yield.

Keywords:

• Aldehyde
• allylation
• bisformamide
• Lewis base

Notes

^a Reaction performed with 0.5 mmol of Lewis base, 0.5 mmol of benzaldehyde, and 1.5 mmol of allylsilane in dichloromethane (2 mL) at −78 °C for 3 days.

^b Determined by Daicel Chiralcel OD (n-hexane/i-PrOH = 19/1).

^c Isolated yields after column chromatography.

^a Reaction performed with Lewis base (0.5 mmol or 2.5 mmol), 0.5 mmol of benzaldehyde, and 1.5 mmol of allyltrichlorosilane in dichloromethane (2 mL) at −78 °C for 3 days.

^b Determined by Daicel Chiralcel OD (n-hexane/i-PrOH = 19/1).

^c Isolated yields after column chromatography (n-hexane/dichloromethane = 2/1).