Metal free and selective activation of one C-F bond in a bound CF3 group.

The first metal free selective C-F bond activation of a CF(3) group was observed with N-heterocyclic silylenes [PhC(NtBu)(2)SiCl] (1) and [CH{(C=CH(2))(CMe)(2,6-iPr(2)C(6)H(3)N)(2)}Si] (2) with PhN=C(CF(3))(2). The reaction proceeds in a 1 : 1 molar ratio to yield the mono C-F bond activated products 3 and 4 with each containing a CF(2) group. Both the reactions proceed through an unprecedented selective activation of one of the C-F bonds rather than forming the [1+2] cycloaddition product containing the three-membered SiNC rings.