Tributylphosphine → (rac.)-(1R*,5S*)-3-{4-[3-(2-Chloro-3,6-difluoro-phenyl)-isoxazol-5-ylmethoxy]-phenyl}-8-aza-bicyclo[3.2.1]oct-2-ene-2,8-dicarboxylic Acid 8-tert-butyl Ester 2-methyl Ester

Participants

Reaction Steps

A mixture of compound B4 (6.80 g, 18.9 mmol), [3-(2-chloro-3,6-difluoro-phenyl)-isoxazol-5-yl]-methanol (6.97 g, 28.3 mmol), ADDP (9.55 g, 37.8 mmol) and PBu3 (85%, 13.8 mL, 56.6 mmol) in toluene (280 mL) was heated to reflux for 1 h. The mixture was allowed to cool to rt, and the solvents were removed under reduced pressure. Purification of the residue by FC (EtOAc/heptane 1:1) yielded the title compound (11.0 g, 99%). LC-MS: tR=1.14 min; ES+: 587.30.

Provenance & Evidence