Process Development for Scale-Up of a Novel 3,5-Substituted Thiazolidine-2,4-dione Compound as a Potent Inhibitor for Estrogen-Related Receptor 1

The development of a reproducible process for multihundred gram production of (Z)-5-((1-(4-chloro-2-(trifluoromethyl)benzyl)-1H-indazol-5-yl)methylene)-3-((3R,4R)-3-fluoro-1-methylpiperidin-4-yl)thiazolidine-2,4-dione (26), a potent and selective inhibitor of estrogen-related receptor 1 (ERR1), is described. This multihundred gram synthesis was achieved via magnesium perchlorate-catalyzed regioselective epoxide ring-opening of tert-butyl 7-oxa-3-azabicyclo[4.1.0]heptane-3-carboxylate (9) with thiazolidine-2,4-dione (6, TZD) to form a diastereomeric mixture tert-butyl 4-(2,4-dioxothiazolidin-3-yl)-3-hydroxypiperidine-1-carboxylate (17), of which the 3-hydroxyl group was functionally transformed to 3-fluoro derivative 19 after treatment with Deoxo-Fluor. Chiral separation of 19 provided the desired diastereomer (3R,4R)-21 that was converted to the secondary amine 23 TFA salt. Reductive amination of 23 produced the key intermediate N-methyl 24. Knoevenagel condensation of 24 with 1-(4-chloro-2-(trifluoromethyl)benzyl)-1H-indazole-5-carbaldehyde (5) produced the final product 26 in 10% overall yield (99.7% HPLC area% with ≥99.5% de) after a convergent eight synthetic steps with the only column purification being the chiral HPLC separation of 3R,4R-21 from 3S,4S-22.