The instant invention relates to intermediates of Formula II, ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are as defined in the specification, and to processes for preparing such intermediates. This invention also relates to processes for preparing compounds of Formula III, ##STR2## and enantiomers thereof, wherein R.sup.2, R.sup.3 and R.sup.4 are as defined in the specification. Compounds of Formula II and Formula III are intermediates in the preparation of a potent .beta..sub.3 adrenergic receptor agonist. The instant invention also relates to processes for preparing the .beta..sub.3 adrenergic receptor agonist using the compounds of Formula II and Formula III.