Silylation Dibutyltin oxide

As described above, optically active aldol adducts are easily obtained by using a stoichiometric amount of chiral diamine, tin(II) triflate, and dibutyltin acetate. To perform the enantioselective aldol reaction by using a catalytic amount of the chiral catalyst, transmetalation of initially formed tin(II) alk-oxide 91 to silyl alkoxide 92 tvith silyl triflate is an essential step (Figure 3.6). When the aldol reaction vas conducted simply by reducing the amount of the chiral catalyst, aldol adducts vere obtained vith low stereoselectivity because Sn-Si exchange occurs slovrly and undesired Me3SiOTf-promoted aldol reaction affords racemic aldol adducts. 

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