The Synthesis of Two Potent β-3 Adrenergic Receptor Agonists

This contribution describes the initial preparation of two potent beta-3 receptor agonists 1 and 2. Subsequent scale up of these two compounds was required for further evaluation and proceeded via a common key amine intermediate 24. Synthesis of this key intermediate by way of a Ritter reaction was a vital step in the sequence. Enantioselective Noyori hydrogenation reactions gave access to the chiral epoxides necessary to make the target compounds. Chemistry was developed for the selective dehalogenation of the 2-chloropyridyl group in the presence of a sensitive isoxazole unit to provide access to 1.