Given a stereochemically defined starting material (either erythro or threo), what stereochemistry would you expect for the products of the following...

Given a stereochemically defined starting material (either erythro or threo), what stereochemistry would you expect for the products of the following electrophilic abstraction reaction:

Let us say that for a related 16e complex LnM(CHDCHDCMe3) gave precisely the same products, but of opposite stereochemistries. What mechanism would you suspect for the reaction?