In a glovebox, an oven dried screw-capped 2 mL vial was charged with a magnetic stir bar, Ni(COD)2 (10 μmol) , carbene ligand Me IPr tBu (10 μmol), degassed (free pump thaw) THF (0.1 mL) was then added and the catalyst mixture was stirred at room temperature for 10 min, during which a dark red solution was formed. Deuterated ketone D-1i (0.1 mmol degassed freeze pump thaw) and COD 2a (0.15 mmol degassed by freeze pump thaw) was then added successively. The vial was sealed with a Teflon-lined screw cap, and running inside the glovebox at room temperature. After 24 h, the vial was shipped outside of the glovebox. The reaction mixture was diluted with dichloromethane and filtered through a plug of silica gel. The crude solution was concentrated in vacuum and subjected to column chromatography 100:1 PE/EA to isolate the product D-3i yield 52% dr 4.0:1. Deuterated (Z)-2-(cyclooct-2-en-1-yl)-2-methyl-2,3-dihydro-1H-inden-1-one (D-3i):