Readily available Ti-based in situ catalytic system for oxo/imido heterometathesis.

We investigate Ti(NEt 2 ) 4 supported on silica dehydroxylated at 700 °C as an easily accessible pre-catalyst for oxo/imido heterometathesis reactions. Being activated with TolNH 2 , the supported Ti amide (SiO)Ti(NEt 2 ) 3 (1) demonstrates catalytic activity in the imidation of ketones with N -sulfinylamines comparable with the most active previously described well-defined imido catalyst (SiO)Ti(N t Bu)(Me 2 Pyr)(py) 2 (2) (Me 2 Pyr = 2,5-dimethylpyrrolyl), which implies the in situ formation of surface imido species in this system. The materials obtained via treatment of 1 with anilines (TolNH 2 (1a) and p -MeOC 6 H 4 15 NH 2 (1b)) were studied with IR, EA and 1 H, 13 C, 15 N and 2D solid-state NMR, although the proposed imido intermediate has not been detected, pointing towards tris-amides (SiO)Ti(NHC 6 H 4 X) 3 (X = Me, OMe) being the major surface species in the isolated materials 1a and 1b. The system 1/TolNH 2 was tested in a range of imidation reactions and demonstrated excellent performance for express high-yielding preparation of ketimines, formamidines, lactone imidates and sulfurdiimines, making it a convenient alternative to the well-defined supported Ti imido catalysts.