To a solution of 500 mg of aldehyde from Step A in 5 mL of 1,2-dichloroethane was added 320 mg of N-methyl-β-alanine benzyl ester hydrochloride and 0.24 mL of DIPEA. After stirring at room temperature for 10 minutes, 470 mg of sodium triacetoxyborohydride was added. The reaction was stirred for 16 hr. The reaction was quenched with sat'd sodium bicarbonate and was extracted twice with methylene chloride. The organic layers were washed with brine, dried over sodium sulfate, combined and evaporated. The residue was purified by FC (20-30% ethyl acetate/hexanes) to give 564 mg of title compound.
