To a solution of acetic acid 7-benzyloxy-1,2,3,4-tetrahydronaphthalen-2-yl ester (5.77 g, 19.5 mmol) in AcOH (30 mL) is added a solution of 90% HNO3 (3.0 mL, ca. 64 mmol) in AcOH (5 mL), copper(II) nitrate hemipentahydrate (3.71 g, 19.8 mmol) and conc. H2SO4 (3 drops) at room temperature. The mixture is stirred at room temperature for 1.5 h and partitioned between EtOAc and aq. KOH. The organic layer is dried over MgSO4, concentrated and chromatographed to afford acetic acid 7-benzyloxy-6-nitro-1,2,3,4-tetrahydronaphthalen-2-yl ester with some impurities. Crystallization from DCM-hexanes yields a precipitate, which is quickly rinsed with Et2O-hexanes to afford pure acetic acid 7-benzyloxy-6-nitro-1,2,3,4-tetrahydro-naphthalen-2-yl ester: 1H NMR (CDCl3) δ 7.66 (s, 1H), 7.48-7.29 (m, 5H), 6.80 (s, 1H), 5.22-5.15 (m, 1H), 5.19 (s, 2H), 3.10 (dd, J=16.0, 8.0 Hz, 1H), 2.95-2.72 (m, 3H), 2.05 (s, 3H), 2.05-1.95 (m, 2H).
