Ethyl Acetate → 7-{2-[2-(tert-Butyldimethylsilanyloxy)ethoxy]thiazol-5-yl}-3,9-diaza-bicyclo[3.3.1]non-6-ene-3,6,9-tricarboxylic acid 3,9-di-tert-butyl ester 6-methyl ester

Participants

Reaction Conditions

Reaction Steps

A sol. of 2-[2-(tert-butyldimethylsilanyloxy)ethoxy]thiazole (3.75 g; 14.46 mmol) in THF (72 mL) was cooled to −78° C. BuLi (1.6M in hexane, 9.5 mL; 15.2 mmol) was added dropwise over 5 min. After completion of the addition, the resulting solution was stirred further at −78° C. for 1 h. ZnCl2 (1.0 M in THF; 16.7 mL, 16.7 mmol) was added dropwise over 5 min, and the reaction mixture was allowed to warm up to rt, and stirred for 1.5 h. A sol. of compound Y (3.84 g; 7.23 mmol) in THF (5 mL) was added, followed by Pd(PPh3)4 (0.25 g; 0.22 mmol). The resulting sol. was stirred at 50° C. for 45 min. The reaction mixture was cooled to rt, and EtOAc (80 mL) was added. The mixture was then poured in sat. aq. NH4Cl (150 mL). The phases were shaken, separated and the aq. phase was extracted with EtOAc (2×150 mL). The combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure. Purification of the residue by FC (EtOAc/heptane 30/70) yielded the title compound (4.59 g, 99%). LC-MS: tR=1.20 min; ES+: 640.31.

Provenance & Evidence