preparation | take 1g of N,N-dimethyl -5-oxo -2-pyrrolidine formamide and 0.92g of sodium borohydride, put them into a 100mL four-mouth bottle, cool down in an ice salt bath, add 30mL of tetrahydrofuran, add nitrogen protection, add 2.08g of iodine tetrahydrofuran solution dropwise, and heat up and reflux after completion. Thin layer chromatography detects the progress of the reaction. After the reaction is over, stop heating, turn the system into an ice bath, add water to destroy the sodium borohydride that did not participate in the reaction, filter, extract the filtrate with ethyl acetate, merge ethyl acetate, and saturate Sodium chloride washes the organic layer, dry and spin to obtain a white solid, namely (S)-1-benzyl -3, 4-dihydroxypyrrolidine-borane complex. Dissolve the white solid in methanol and reflux for 8h, spin dry, add 10mL of ethyl acetate and 10mL of dilute hydrochloric acid (0.1N), separate the water layer, neutralize sodium hydroxide to pH 8, extract the product from ethyl acetate, concentrate under reduced pressure to obtain oily liquid, and recrystallize with acetone to obtain gray-white solid (R)-2-(dimethylaminomethyl) pyrrolidine hydrochloride. |