Syntheses of homochiral 1,2-ferrocene-functionalized Lewis acids and acid/base pairs

We report a facile approach for the synthesis of homochiral 1,2-disubstituted ferrocene-functionalized Lewis acids and acid/base pairs. The synthesis is based on chiral induction facilitated by the ortho sulfinyl subsitutent in S-Fc{S(O)p-tol}, S-1, to obtain the key intermediate S,Sp-1,2-fc{S(O)p-tol}(BMes2), S,Sp-2a (p-tol = C6H4Me-4, Mes = C6H2Me3-2,4,6). Subsequent substitution of the –S(O)p-tol substituent in S,Sp-2a gives access to a range of enantiomerically pure Sp-1,2-ferrocene-functionalized Lewis acids and acid/base pairs including the first homochiral 1-phosphino-2-borylferrocene. Enantiomeric excesses (e.e.s) of >95% have typically been achieved using this methodology.