Study On The ?-hydroxylation Of ?-dicarbonyl Compounds

The ?-hydroxy-?-dicarbonyl moiety is a common structural motif in a variety of natural products and pharmaceuticals.Moreover,this functional unit appears in key intermediates in many multi-step reaction sequences.To date,a number of methods have been developed for the preparation of?-hydroxy P-dicarbonyl moieties.Firstly,reactions of?-hydroxylation of ?-dica'rbonyl compounds were classified by the oxidants for the racemic synthesis and by chiral catalysts for the enantioselective ones.On this basis,?-hydroxylation of?-dicarbonyl compounds using in situ generated hypervalent iodine catalysts and phase-transfer N-Spiro chiral quaternary ammonium bromide catalysts were produced.In the second chapter,the hypervalent iodine which generated by tetrabutylammonium iodide(TBAI)and potassium peroxymonosulfate(Oxone)shows excellent oxidation performance and accelerates the reaction efficiently at room temperature(up to 94%yield),and tolerates a wide scope of functionalities.Through the controlled experiment,we proposed a possible reaction mechanism for this catalytic system.In the third chapter,N-spiro chiral quaternary ammonium bromide as the chiral phase-transfer catalyst for the efficient enantioselective ?-hydroxylation of ?-dicarbonyl compoundswas reported(up to 99%yield;up to 93%ee).In conclusion,we have developed two novel oxidation systems to generate hydroxyl at a-position of ?-dicarbonyl compounds both in a racemic and enantioselective way,opens a new avenue for the preparation of this kind of biologically important molecules.