Amino Acid Derived Chiral Bifunctional(Thio)urea Tertiary-Amines Catalyzed Asymmetric Henry Reaction Of ?-trifluoromethyl Ketones

This dissertation focuses on the study of designing and synthesizing of bifunctional(thio)urea-tertiary amine catalysts based on natural ?-amino acids,and application on the asymmetric Henry reaction of nitroalkanes and ?-trifluoromethyl ketones.It is difficult to predict the stereoinduction exerted from the chiral catalytic component of the ion pair due to its intrinsic nondirectional nature.Therefore,It is best suited to solve this problem with bifunctional catalyst that combine a site with Br(?)nsted base character with another site with hydrogen-bond donor ability,for the basic site can activate the nucleophile while hydrogen-bond site can stimulate the electrophile.In addition,the higher degree of stereochemical order in the transition state usually results in better and more predictable asymmetric induction.Given that ?-amino acids,known as the non-racemic precursors from the chiral pool,are relatively cheap starting materials,it is reasonable and practical to modify them into chiral bifunctional tertiary-amine(thio)urea catalysts through several synthetic transformations.?-nitroalcohol,generated from Henry reaction,could be easily transformed into some pharmaceutical intermediates through corresponding organic reactions,such as reduction to ?-aminoalcohol and dehydration to conjugated nitroalkene.In light of chiral non-racemic tertiary alcohol which contains an?-trifluoromethyl group representing interesting and promising compounds for medicinal chemistry and agrochemistry,it is essential to construct some relavent compounds such as ?-trifluoromethyl-?-nitroalcohols.