A mixture consisting of 3.7 (27.2 mmol) of ZnCl2, 3.2 g (53 mmol) of NaCNBH3 and 60 mL of methanol was prepared to which was added a solution of 18 g (51.7 mmol) of the amine 1 in 180 mL of methanol. After cooling to 10°-15° C. 12.4 mL of 37% formaldehyde (165 mmol) was added dropwise over a 2-3 minute period. The reaction was stirred for 1 hour and monitored by silica gel TLC with elution using a 60:10:1(v/v/v/) mixture of chloroform/methanol/concentrated ammonia (solvent A). One hundred milliliters of water was added and the mixture concentrated to a volume of 200 ml. Ethyl acetate (200 mL) was added and the pH raised to 10.5 with 10% NaOH. The ethyl acetate was separated and the pH of the aqueous phase readjusted to 10.5 and extracted with 200 mL of fresh ethyl acetate. The ethyl acetate extracts were combined, washed with NaCl, dried over Na2SO4, filtered and concentrated to yield, after drying overnight under high vacuum, 14.86 g of viscous oil.
