N,N′-di-(1,3-dimethylbutyl)-p-phenylenediamine (17 g, 61.5 mmol) and 2-ethylhexanal (18.53 g, 144.5 mmol) were dissolved in dichloromethane (500 mL) and were stirred together in a 1 liter round bottomed flask fitted with a condenser and magnetic stirring at room temperature whilst sodium triacetoxyhydroborate (30.63 g, 144.5 mmol) was added portionwise over 1 hour. The mixture was left standing for a total of 18 hours. The crude product was stirred with 150 ml water for a few minutes followed by addition of aqueous sodium carbonate solution (60 g in 250 ml water) in portions. Most of the effervescence subsided after 50% of this had been added. The mixture was stirred with a further 100 ml water and separated using a separating funnel. The organic phase was washed with water (500 ml+750 ml) and brine (500 ml). It was then dried with magnesium sulphate, filtered through celite 521 and evaporated to leave a dark brown oil. The product was chromatographed (eluent 5% EtOAc in heptane). Relevent fractions were combined and concentrated to afford the product as a dark oil (28.6 g, 93% yield).
