A chemoenzymatic synthesis of β3 agonist 1 suitable for large scale preparation is described. The key chiral 3-pyridylethanolamine intermediate (R)-7 was prepared via an improved Neber rearrangement and a yeast-mediated asymmetric reduction. The tetrazolone fragment of the molecule was constructed via a dipolar cycloaddition between 1-(cyclopentyl)-3-propylazide and p-chlorosulfonyl phenylisocyanate. Sulfonamide coupling of these two intermediates under Shotten-Baumann conditions, followed by a borane reduction of the amide afforded 1 in 20-32% overall yield from 3-acetylpyridine.
All Science Journal Classification (ASJC) codes
- Drug Discovery
- Organic Chemistry