[Snake]

Hey guys.. i have this question which asks to show the mechanism with stereochemistry.. i don't know how to do it showing sterochemistry can anyone help pleasee..

[movies]

In this reaction you will make predominantly one diastereomer of product in favor of the other.  The idea of the question is to draw a transition state which explains why the one diastereomer is preferred.

Here is a hint: the diastereomers would arise from attack at one of the two faces of the cabonyl carbon.  How do you think the presence of the t-butyl group will affect these transition states?  It might not be an obvious steric interaction, but something which is a consequence of the arrangement of the t-butyl group in space (axial or equatorial).  Think about how that affects other substituents around the ring as well.