The Asymmetric Aldol Reaction Of Phenylglyoxal With Hydroxyacetone

A series of chiral amine and primary amine-thiourea catalysts were prepared and used in the catalytic asymmetric Aldol reaction of phenylglyoxal and hydroxyacetone. After the optimization of the reaction conditions, we found that both of anti- and syn-condensation products could be obtained via the change of catalysts. When quinine-derived primary amine 5e was used to promote this reaction in chloroform at0 oC with 20 mol% DNBA as additive, the anti-Aldol products was produced, with satisfactory yields( up to 92%), excellent enantioselectivities( up to 100%) and diastereoselectivities( up to 93 : 7 dr). Alternatively when other types of primary-amine was used as catalysts, the product with syn-configuration was obtained, in satisfactory yields( up to 100% yield), good diastereoselectivities( 6 : 94 dr), albeit the ee is moderate( 44 %). The reaction conditions for the syn-selective aldol reaction need to be further optimized.