Although reagents can always add to an alkene from either side, sometimes one side of the...

Although reagents can always add to an alkene from either side, sometimes one side of the double bond is more sterically hindered, so an unequal mixture of addition products results. For example, when X is treated with H2 in the presence of a Pd catalyst, 80% of the product mixture contains the cis isomer Y and only 20% is the trans isomer Z. Thus, addition of H2 occurs predominantly on the side opposite to the bulky tert-butyl group, resulting in a new equatorial C—H bond. Keeping this in mind, what is the major epoxidation product formed from X under each of the following reaction conditions: (a) mCPBA; or (b) Br2, H2O followed by NaH?