Octahedral Iridium Or Rhodium Complex Catalyzed ?-chlorination And Enantioselective Conjugate Addition Reaction Of 2-acyl Imidazoles

In this dissertation we realized a catalytic protocol for the a-chlorination of 2-acyl imidazoles with TsC1 catalyzed by an octahedral iridium complex and catalytic hydroxyamination of a,(3-unsaturated 2-acyl imidazoles with N-protected hydroxyl amines catalyzed by chiral-at-metal Rh(III)complex(0.5-2 mol%).Section I:This section disclose an octahedral iridium complex catalyzed a-chlorination of 2-acyl imidazoles with TsCl as chlorinating agent in the presence of stoichiometric amount of Na2HPO4 as base.By investigation of the catalysts,temperature,bases and solvents,the corresponding a-chlorinated products were obtained in good to excellent yield(up to 97%).The mechanistic studies indicated that radical process might be involved in this transformation.Substrates investigation demonstrated that various functionalities were tolerated in our optimal reaction conditions.Aromatic acyl imidazoles with either electron-donating or electron-withdrawing groups on the aromatic rings delivered the corresponding products in good to excellent yields,while aliphatic acyl imidazoles exhibited no reactivity in optimal reaction conditions.Section II:This section describes that chiral-at-metal rhodium(III)complex catalyzed hydroxyamination of ?,?-unsaturated 2-acyl imidazoles with N-protected hydroxyl amines to afford the corresponding adducts in moderate to good yields with excellent enantioselectivities.After optimization of the reaction conditions on catalysts,bases,solvents and temperature,the corresponding aza-Michael adducts were obtained with excellent enantioselectivity(up to 99.5%ee).It is worthy to note that:(1)In the absence of chiral-at-matal complex as catalyst,the oxa-Michael adducts was obtained instead of aza-Michael adducts;(2)In addition,chiral-at-rhodium(III)complex are much better than chiral-at-iridium(III)complex in terms of the reaction time;(3)Good yields and excellent enantioselectivities could be obtaiend with lower catalyst loading(0.5-2 mol%);(4)Substrates investigation demonstrated that ?,?-unsaturated acyl compounds with alkyl substitution at the(3-position were tolerated under the optimal reaction conditions.However,substrates with aryl substitution on P-position showed relatively lower reactivity.