To a mixture of 4-n-octylaniline (0.21 g; 1 mmol), tert-butyl 5-formyl-2,2-dimethyl-1,3-dioxan-5-ylcarbamate (Ooii et al, J. Org. Chem., 2004, 69, 7765; 0.26 g; 1 mmol) and NaBH(OAc)3 (0.3 g; 1.4 mmol) in 1,2-dichloroethane (3.5 ml) AcOH (0.06 ml; 1 mmol) was added at room temperature with stirring under N2. After stirring for 2 h, the mixture was diluted to 20 ml with Et2O, washed with 1.M NaOH (2×5 ml), brine and dried over anhydrous MgSO4 and filtered. The filtrate was evaporated to dryness under reduced pressure. The residue was dissolved in hexane (5 ml) and kept in the freezer (−18° C.) overnight. The crystals formed were filtered off, washed with small volume of hexane and dried to give the title compound (0.32 g; 71%), as colourless crystals. 1H-NMR (CDCl3) 6.96 (d, 2H, J=8.4 Hz); 6.58 (d, 2H, J=8.4 Hz); 4.84 (broad s, 1H); 4.01 (d, 2H, J=11.9); 3.85 (broad s, 1H); 3.8 (d, 2H, J=11.9 Hz); 3.44 (s, 2H); 2.46 (t, 2H, J=7.9 Hz); 1.5 (m, 2H); 1.45 (s, 3H); 1.43 (s, 9H); 1.42 (s, 3H); 1.26 (m, 10H); 0.86 (t, 2H, J=6.95 Hz).
