Determination of the extent to which an SE2′ reaction of a propargylsilane is anti

The propargylsilane, 1,3-bistrimethylsilylbut-1-yne, 11 reacts with aldehydes in the presence of titanium tetrachloride in anti SE2′ reactions, but with a low level of stereospecificity, 75:25 with 2,4-dinitrobenzaldehyde and close to 50:50 with isobutyraldehyde.