Toward ideal (trans)esterification by use of fluorous distannoxane catalysts.
1,3-Disubstituted tetrakis(fluoroalkyl)distannoxanes, (XR(2)SnOSnR(2)Y)(2) (R = C(6)F(13)C(2)H(4) and C(4)F(9)C(2)H(4)), are highly fluorophilic and exhibit large partition coefficients in favor of fluorocarbon solvents over common organic solvents due to a double-layered structure where the stannoxane core is covered by fluoroalkyl groups. Under catalysis of these Lewis acids, fluorous technology allows novel transesterification and esterification in which a 100% yield of the desired esters is achievable with reactants in a strict 1:1 ratio. The catalysts are recovered from the fluorous phase quantitatively. More practically, the catalyst in fluorocarbon solution can be recycled for use in the next reaction repeatedly.
Otera
Junzo
J
Department of Applied Chemistry, Okayama University of Science, Ridai-cho, Okayama 700-0005, Japan.