Reaction Steps
Dimethyl malonate 3a (10 g, 28 mmol), TEBAC (0.33 g, 1.4 mmol) (or 18-Crown 6) and 1N NaOH (120 ml) are stirred at 100° C. for 3 days. Cooled to 25° C. the mixture is extracted with tert-butyl methyl ether and the organic phase, which contains aldehyde 5, is discarded. 100 ml 2 N HCl are added to the aqueous phase, which is extracted with tert-butyl methyl ether. The organic phase is washed with water, dried over MgSO4, filtered and evaporated to give 7.15 g of crude bis-acid 1c (87%). Analytical data: 1H-NMR (400 MHz, CDCl3): δ 0.96 (s, 6 H), 1.13 (d, 3 H), 1.35-1.6 (6 H), 1.56 (s, 3 H), 1.85-2.1 (4 H), 3.5 (m, 1 H), 7.6 (d, 1 H) ppm. 13C-NMR (400 MHz, CDCl3): δ 19.1 (q), 19.4 (t), 19.8 (q), 26.5 (t), 28.5 (2 q), 32.7 (t), 34.8 (s), 35.6 (d), 36.9 (t), 39.7 (t), 120.0 (s), 127.3 (s), 136.8 (s), 168.3 (s), 169.2 (d), 1669.7 (s). MS (DIP, EI): m/z (%) 294 (M+, 67), 279 (8), 276 (14), 261 (18), 258 (17), 243 (100), 233 (12), 215 (22), 190 (16), 187 (15), 175 (32), 151 (14), 144 (44), 135 (32), 126 (14), 123 (31), 121 (16), 107 (9), 95 (9). IR (film): 2969 (m), 2929 (m), 2867 (m), 1701 (s), 1367 (m), 1262 (m), 1237 (m), 1199 (s), 1172 (m), 1067 (m), 842 (m), 761 (m).
