A highly convergent large scale synthesis of a 15-membered macrocyclic hepatitis C virus (HCV) protease inhibitor BI 201302 was achieved, in which the key features are the practical macrocyclization by Ru-catalyzed ring-closing metathesis (0.1 mol % Grela catalyst, 0.1–0.2 M concentration) and the efficient sulfone-mediated SNAr reaction.
Significance
The synthesis of the HCV protease inhibitor BI 201302 features an efficient ruthenium-catalyzed ring-closing metathesis reaction (0.1–0.2 M) requiring only 0.1 mol% of the Grela catalyst E to generate the 15-membered macrocycle F. This enhanced efficiency was achieved by installing a Boc substituent on the nitrogen of fragment D.
Comment
The SNAr reaction using a phenylsulfonyl leaving group in quinoline derivative H was more efficient than the reaction with the corresponding chloride (92% vs 40% yield). Potassium 3,7-dimethyl-3-octanoxide (KDMO) was used as a base instead of t-BuOK because transcarbamoylation byproducts (1–2%) were easily removed by crystallization.
