Synthesis
The reaction was carried out under nitrogen. To the solution of aluminum chloride (14.5 g, 100 mmol) in 40 mL of nitromethane was added malonodinitrile 26 (6.6 g, 100 mmol). The temperature of the reaction mixture was kept between -15 and -20 °C, and tert-butyl bromide (22 g, 160 mmol) was added over a period of 30-45 min. The reaction mixture was allowed to warm to 0-5 °C and was maintained at that temperature. The reaction was monitored by TLC; the eluent was 30% EA/hexane. More tert-butyl bromide was added to complete the reaction. The reaction was worked up after 15 h by addition of a saturated solution of sodium bicarbonate to neutralize the HBr produced. The reaction mixture was extracted with methylene chloride. The organic layer was dried over anhydrous sodium sulfate and concentrated over vacuum. The 27 obtained (8.5 g, 70% yield) can be used for the next step without purification. t-Butylmalonodinitrile 27, yield (8.5 g, 70%) 1H NMR (300 MHz, CDCl3): δ 3.42(s, H), 1.24 (s, 9H).
