[C:1]([O:5][C:6]([NH:8][CH:9]1[CH2:11][CH:10]1[CH:12]=[CH2:13])=[O:7])([CH3:4])([CH3:3])[CH3:2].B.C1C[O:18]CC1.[OH-].[Na+].OO.C(=O)([O-])[O-].[K+].[K+]>O1CCCC1.C(OCC)(=O)C.C(Cl)(Cl)Cl.CO>[C:1]([O:5][C:6]([NH:8][CH:9]1[CH2:11][CH:10]1[CH2:12][CH2:13][OH:18])=[O:7])([CH3:4])([CH3:3])[CH3:2]
N-tert-Butoxycarbonyl-2-ethenylcyclopropylamine (3.96 g, 21.6 mmol) from Step C was dissolved in 21 mL of tetrahydrofuran (THF). A 1M solution of borane THF.complex in THF (43.27 mL, 2 equivalents) was added at 0° C. under a nitrogen atmosphere. After the reaction mixture was stirred at 0° C. for 2.5 h, TLC analysis (on silica gel plates eluted with 25% ethyl acetate in hexane) showed the presence of starting material. A second aliquot (2 mL) of the borane-THF solution was added. The reaction mixture was allowed to warm to ambient temperature and stirred at ambient temperature for 0.5 h then cooled to 0° C. again. A 6N aqueous solution of sodium hydroxide (25.1 mL, 3.5 equivalents) was added to the reaction mixture followed by 30% aqueous hydrogen peroxide solution (7.6 mL, 1.5 equivalents) and the resultant solution was stirred at 0° C. for 10 minutes. The reaction mixture was again allowed to warm to ambient temperature and stirred at ambient temperature for 1.5 h. Anhydrous potassium carbonate was added as a solid. The reaction mixture was then diluted with 100 mL of ethyl acetate, washed with 100 mL of 1N aqueous phosphoric acid solution, 100 mL of saturated sodium bicarbonate solution, dried over anhydrous magnesium sulfate and concentrated in vacuo. Flash chromatography on silica gel with solvent gradient elution of from 1% methanol in chloroform, initially, to a final concentration of 2% methanol in chloroform yielded 4.37 g (100% yield) of N-tert-butoxycarbonyl-2-(2'-hydroxyethyl)cyclopropylamine. CDI NH3MS, M/Z: 202 (M+H)+.
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