p-Toluenesulfonic acid → (rac.)-(1R*,5S*)-7-(4-Hydroxy-phenyl)-3,9-diaza-bicyclo[3.3.1]non-6-ene-3,6,9-tricarboxylic Acid 3-tert-butyl Ester 6-ethyl Ester 9-(2,2,2-trichloro-1,1-dimethyl-ethyl) Ester

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Reaction Steps

Compound B10 (7.58 g, 10.7 mmol) was dissolved in MeOH (110 mL) and p-TsOH (2.03 g, 11.8 mmol) was added. The mixture was stirred at rt for 2 h, and aq. 10% Na2CO3 (200 mL) was added. The solvents were partially removed under reduced pressure, and the resulting suspension was extracted with EtOAc. The org. extracts were filtered and washed with aq. 10% Na2CO3 and brine. The org. layer was dried over Na2SO4, filtered, and the solvents were removed under reduced pressure. Purification of the crude by FC (EtOAc/heptane) yielded the title compound (2.10 g, 33%). LC-MS: tR=1.09 min, ES+: 593.25.

Provenance & Evidence