“…The oily residue was then crystallized (5.7 g, 58%) from ethyl acetate-hexane, mp 91-93 °C. The anhydride product 14 which was homogeneous on silica thin layers (ethyl acetate) showed an Rf different from 18 and gave the expected IR bands: NMR (CDC13) 1.44 (9 H, s, 3 CH3), 1.56-2.72 (4 H, complex, CH2C=0 and CH2), 4.24-4.64 (1 H, m, -CH), 5.30 (2 H, s, benzyl), 5.30-5.48…”