Dichloromethane → (1S,2R,3S,4R)-3-(2-cyclopropyl-ethylamino)-bicyclo[2.2.1]heptane-2-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

A 1.4 M solution of cyclopropylacetaldehyde in dichloromethane (prepared as described in Example 23a, 3.4 mL, 4.76 mmol) was added to a solution of (1S,2R,3S,4R)-3-amino-bicyclo[2.2.1]heptane-2-carboxylic acid ethyl ester (prepared as described in Example 6k, 580 mg, 3.17 mmol) in anhydrous methanol (15 mL) at 25° C. under a nitrogen atmosphere. After stirring for 20 min, glacial acetic acid (0.6 mL) was added. The solution was cooled to 0° C., sodium triacetoxyborohydride (1.7 g, 7.93 mmol) was added, and the resulting mixture was stirred at 25° C. for 20 h. The reaction mixture was quenched with saturated aqueous sodium bicarbonate solution (25 mL) and was extracted with ethyl acetate (3×60 mL). The combined organic layers were washed with saturated aqueous brine solution, dried over sodium sulfate and filtered. The filtrate was concentrated in vacuo to afford the desired product, (1S,2R,3S,4R)-3-(2-cyclopropyl-ethylamino)-bicyclo[2.2.1]heptane-2-carboxylic acid ethyl ester (676.4 mg, 2.69 mmol, 84.9%), as a yellow oil. LC-MS (ESI) calcd for C15H25NO2 251.19, found 252.0 [M+H+].

Provenance & Evidence