Design of Organocatalysts for Asymmetric Direct Syn-Aldol Reactions
摘要:
Two new organocatalysts 3a and 3b, derived from L-leucine and (S)-beta-amino alcohols that were prepared from L-valine, were designed and afforded the direct syn-aldol reactions of a wide scope of aldehydes with various ketones with an excellent diastereomeric ratio of up to >20/1 and enantioselectivities of up to 99% ee.
Chiral primary amino amide organocatalysts were designed and synthesized as new organocatalysts for the enantioselective Michael addition of 4-hydroxycoumarin with alpha,beta-unsaturated ketones to produce chiral warfarin (up to 56% ee with up to 92% yield).