Reaction Steps
The mixture of carbamate (Example 7; 360 mg 0.00094 mol, cis and trans mixture) and lithium hydroxide (248 mg, 0.0104 mol) in ethanol (6.0 mL, 0.10 mol) and water (2.0 mL, 0.11 mol) was heated to reflux for overnight. LCMS showed reaction completed. The solvent was removed under vacuum and the residue was partitioned between water/CH2Cl2. The aqueous layer was extensively extracted with CH2Cl2. The combined organic phase was dried over Na2SO4. The concentrated residue was taken up into DCM and subjected to chromatographic purification with CH2Cl2/MeOH (10:90 to 80:20) to give the product (220 mg, 66%). Separation on ChiralPak-ADH (5μ, 4.6 mm×250 mm, 2 mL/min, 25% (0.3% DEA in MeOH) in CO2, 100 bar, 36° C.) gave peak 1, Rf=8.373 min, 87 mg (87.9% yield, 96.4% ee), and peak 2, Rf=12.479 min, 74 mg (74.7% yield, 97.0% ee). Peak 1 was purified on Si gel (0-100% MeOH/DCM) to give 26.2 mg; peak 2 was purified on Si gel (0-100% MeOH/DCM) to give 44.3 mg. LCMS 339.71 ([M−NH2]+, 100%). 1H NMR (400 MHz, CD3OD) δ ppm 0.93 (t, J=6.9 Hz, 3H), 1.14 (ddd, J=14.7, 13.4, 3.0 Hz, 2H), 1.24-1.39 (m, 7H), 1.45 (ddd, J=14.7, 12.5, 3.3 Hz, 2H), 1.56 (s, 3H), 1.89 (br d, J=13.0 Hz, 2H), 2.22 (brd, J=12.5 Hz, 2H), 3.70 (d, J=10.9 Hz, 1H), 3.76 (d, J=10.9 Hz, 1H), 4.37 (m, 1H), 7.11 (dd, J=9.0, 2.6 Hz, 1H), 7.21 (d, J=2.5 Hz, 1H), 7.55 (dd, J=8.7, 2.0 Hz, 1H), 7.74 (d, J=6.6 Hz, 1H), 7.76 (d, J=6.9 Hz, 1H), 7.84 (d, J=1.9 Hz, 1H).
