Copper (II) acetate monohydrate (3.70 g, 0.05 eq) and bis-camphorethylenediamine (N1,N2-bis[(1R,2R,4R)-1,7,7-trimethylbicyclo[2.2.1]hept-2-yl]-1,2-ethanediamine) (7.38 g, 0.06 eq) were charged to a reactor, followed by ethanol (200 mL, 2 vol). The contents were heated to 50-60° C. for ˜1 h or until all solids dissolved, then cooled to room temperature and stirred, at which time a solution of 3-({3-[(phenylmethyl)oxy]propyl}oxy)benzaldehyde in ethanol (100 g, 1 eq in 50 mL, 0.5 vol) was charged. The reaction mixture was cooled to −10° C. to −20° C., whereupon nitromethane (112.7 g, 5 eq) was added slowly to the reaction, maintaining a temperature below −10° C., followed by diisopropylethylamine (1.94 mL, 1.44 g, 0.03 eq). The reaction temperature was maintained at −10° C. for ˜22-30 h. When the reaction was complete, a room temperature solution of 1 N HCl (250 mL, 2.5 vol) and t-butyl methyl ether (TBME, 500 mL, 5 vol) were charged to the reaction vessel. Following the addition, the contents were stirred for ˜5 minutes and brought to 20° C. (˜room temperature), and then the layers were allowed to separate and the aqueous phase removed. The organic phase was then washed 2× with water (250 mL, 2.5 vol) and each time the aqueous phase removed. TBME was then distilled off and replaced with absolute ethanol.
