Reversible C=C Bond Activation by an Intramolecularly Coordinated Antimony(I) Compound.

The reaction of N,C,N-chelated stibinidene ArSb (1) (Ar=C6 H3 -2,6-(CH=NtBu)2 ) with selected N-alkyl/aryl-maleimides RN(C(O)CH)2 (R=Me, tBu, Ph) gave the addition products with bridged bicyclic [2.2.1] structure containing an antimony atom at the bridgehead position, fused with a 6-membered benzene and a 5-membered N-alkyl/aryl-pyrrolidine ring. These compounds were completely characterized. More importantly, additional studies showed that these reactions are reversible in solution, thereby representing an unprecedented reversible activation of a C=C bond by an antimony(I) compound.