[CH2:1]([N:8]1[CH2:13][CH2:12][O:11][CH:10]([CH:14]([OH:18])[CH:15]([CH3:17])[CH3:16])[C:9]1=O)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1>O1CCCC1>[CH2:1]([N:8]1[CH2:13][CH2:12][O:11][CH:10]([CH:14]([OH:18])[CH:15]([CH3:16])[CH3:17])[CH2:9]1)[C:2]1[CH:3]=[CH:4][CH:5]=[CH:6][CH:7]=1To a stirred solution of 53 (1.97 g, 7.47 mmol) in tetrahydrofuran (50 ml) at room temperature under nitrogen was added borane-tetrahydrofuran complex (30 ml of a 1M solution, ca 4 eq.). The reaction was heated to 60° C. and followed by TLC-analysis. When all starting material had been consumed a few drops of methanol were added followed by a similar amount of 1N hydrochloric acid and heating was continued for another hour. Organic solvents were removed in vacuo and the remaining solution was poured onto 1M potassium carbonate solution (30 ml), extracted with diethyl ether. The organic layers were dried over magnesium sulphate and purified by column chromatography (gradient from 15% ethyl acetate in hexane [v/v]) gave 54 (1.8 g, 97%). MW 249.36; C15H23NO2; LCMS (6 min method): m/z 250 [M+H]+; RT=0.838.
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