Study On Asymmetric Reduction Of Methyl Ketones Under The Chiral Resources Of Natural (+)-Borneol And (-)-Isoborneol

In the article,the asymmetric reductions of methyl ketones under the inductions of (+)-borneol(natural) and (-)-isoborneol(be prepared) are introduced.Firstly, the bromides of (+)-bornyloxymagnesium and (-)-isobornyloxymagnesium can be prepared by adding the etheral solution of (+)-borneol and (-)-isoborneol respectively to the solution of n-butylmagnesium bromide in ether.In benzene the methyl ketones can be reduced by the bromides.According to the theory of Meerwe- in-Ponndorf the predominant configurations of the secondary alcohols under the ind- uction of (-)-isoborneol are R and under the induction of (+)-borneol are S.Secondly, (+)-bornyloxyaluminum dichloride and (-)-isobornyloxyaluminum dic- hloride can be prepared from (+)-borneol and (-)-isoborneol under the conditions of LiAlH₄/AlCl₃ in ether.The methyl ketones can be reduced by the dichlorides,and get the secondary alcohols wich their predominant configurations are S and R respectiv- ely.Thirdly, the influence factors of the reducing reactions including time,temperatu- re,solvent and the proportion of the reactants are studied,and find the optimum conditions.Fourthly,we have compared the yields and ee% of the secondary alcohols which are reduced by (+)-bornyloxyaluminum dichloride and (+)-bornyloxymagnesium bro mide and the yields and ee% of the secondary alcohols which are reduced by (-)-iso- bornyloxyaluminum dichloride and (-)-isobornyloxymagnesium bromide.And we also have compared the ee% of the secondary alcohols under the inductions of borneol and isoborneol.All the alcohols are analyzed by IR,¹HNMR,¹³CNMR and melting point,boiling point and so on.Fifthly,as for the p- and m- nitroacetophenones under the induction of (+)-borneol, we can get the secondary alcohols which their predominant configurations are R.The results are not accordance with the theory of Meerwein-Ponndorf.In the thesis,we analyze the phenomenon and give the intepretation.