Tetrabutylammonium fluoride (0.77 mL, 0.769 mmol, 1M in THF) was added to a solution of 46 (0.355 g, 0.769 mmol) and glacial acetic acid (0.04 mL, 0.769 mmol) in THF (4 mL) at rt. The reaction mixture was stirred at rt for 3 h then diluted with t-BuOMe and washed successively with water and brine. The organic layer was dried (Na2SO4) and evaporated to dryness to give a crude product which was purified by column chromatography (three times—first with: EtOAc:cyclohexane 3:7+1% acetic acid, then with neat CH2Cl2 and finally with CH2Cl2:methanol 40:1) to yield ZSB-83 (65 mg, 25%):
