Electrophilic activation of alkynes for enyne cycloisomerization reactions with in situ generated early/late heterobimetallic Pt-Ti catalysts.

In situ formation of heterobimetallic Pt-Ti catalysts enables rapid room temperature catalysis in enyne cycloisomerization reactions. The Lewis acidic titanium atom in the ligand framework is shown to be essential for fast catalysis. A range of enyne substrates are efficiently cyclized to carbocycles and heterocycles in high yield.

Origin of fast catalysis in allylic amination reactions catalyzed by Pd-Ti heterobimetallic complexes.

Experiments and density functional calculations were used to quantify the impact of the Pd-Ti interaction in the cationic heterobimetallic Cl2Ti(N(t)BuPPh2)2Pd(η(3)-methallyl) catalyst 1 used for allylic aminations. The catalytic significance of the Pd-Ti interaction was evaluated computationally by examining the catalytic cycle for catalyst 1 with a conformation where the Pd-Ti interaction is intact versus one where the Pd-Ti interaction is severed. Studies were also performed on the relative reactivity of the cationic monometallic (CH2)2(N(t)BuPPh2)2Pd(η(3)-methallyl) catalyst 2 where the Ti from catalyst 1 was replaced by an ethylene group.

Allylic aminations with hindered secondary amine nucleophiles catalyzed by heterobimetallic Pd-Ti complexes.

Phosphinoamide-scaffolded heterobimetallic palladium-titanium complexes are highly effective catalysts for allylic aminations of allylic chlorides with hindered secondary amine nucleophiles. Three titanium-containing ligands are shown to assemble active catalysts in situ and enable catalysis at room temperature. A variety of sterically bulky secondary amines are efficiently allylated in high yields with as little as 1 mol % palladium catalyst.