反应详情

To a solution of racemic (2:1) in favor of trans tert-butyl (3-hydroxycyclobutyl)carbamate (16.8 g, 90 mmol) and 4-nitrobenzoic acid (10.97 ml, 102 mmol) in THF (300 mL) were added triphenyl phosphorus (30.0 ml, 130 mmol) and (E)-diisopropyl diazene-1,2-dicarboxylate (25 ml, 124 mmol) dropwise at 0° C. The resulting mixture was stirred at room temperature for 18 h. The reaction was concentrated and the crude material purified by flash silica gel chromatography on ISCO eluting with 0-40% EtOAc/hexanes to give a mixture cis and trans products. The mixture of isomers was purified by chiral separation to give the desired trans isomer trans-3-((tert-butoxycarbonyl)amino)cyclobutyl 4-nitrobenzoate (17.4 g, 51.7 mmol, 87% yield).

1. concentrationThe reaction was concentrated
2. customthe crude material purified by flash silica gel chromatography on ISCO
3. washeluting with 0-40% EtOAc/hexanes
4. customto give a mixture cis and trans products
5. additionThe mixture of isomers
6. customwas purified by chiral separation