3. (5 pts) The two interconverting enantiomers of thalidomide are shown below. When an enantiopure sample of either isomer is treated with base (e.g. NaOH in H2O ) the optical rotation of the material changes to zero over time. Draw a mechanism, including all important resonance structures for intermediates, that explains how the conversion happens. Be sure to take into account all acid-base reactions that could occur