Asymmetric Addition Reaction Of Chiral Tert Butanesulfinyl Imines

The chiral amines are extremely important structural units due primarily to their widespread use as crucial internediates for the synthesis of pharmaceutical compounds as well as their presence in numbers of biologically active compounds as the key skeleton. They are important intermediates and building blocks in organic synthesis. The asymmetric addition reactions of chiral imines have been the most effective synthetic routs to organic amines.Because of the special peoperties of fluorine atom, fluorinated compounds are different from non-fluorinated compounds, which play a significant role in pharmaceutical, agrochemical and materials sciences. To the best of our knowledge, fluorinated imines are introduced into molecules as the resource of fluorine-containing group.Due to the steric hindrance and electronic effects, reactivity of ketimines is inferior to that of aldimines. However, chiral ketimines can be improved greatly because of electron withdrawing effect of chiral tert-butanesulfinyl group. The chiral tert-butanesulfinylketimines have been used to synthesize chiral amines containing one stereogenic center. Therefore, the study of chiral ketimines has certain research value.In this thesis, chiral tert-butanesulfinylfluorinated aldimines and chiral tert-butanesulfinylketimines taken as the research subjects, were studied to react with different nucleophiles. Finally, a series of amines with high enantiomeric purity were successfully obtained. The dissertation is divided into the following two parts:In the first part, a highly diastereoselective synthesis of of β-fluorinated β-amino acids via addition of acetates to (SS)-N-tert-butanesulfinyl-fluorinacetaldimines has been revealved. This method tolerates a wide range of amino acids, giving the products in moderate to excellent yields and good diastereoselectivities. At the same time, the absolute configuration of the products and the reasonable mechanism has also been explored. In addition, the chiral auxiliary group was removed successfully. And the free amino could be further transformed into tetrahydro-6-oxo-pyrimidine.In the second part, Asymmetric Mannich-type reactions between lithiated benzo[d]thiazoles and tert-butanesulfinylketimines occur with good yields and excellent diastereoselectivities. The chiral tert-butanesulfinyl group could be readily cleaved under mild acidic condition without any erosion of enantiomeric purity. Meanwhile, a chelated transition state model of mechanism was confirmed.