Toluene → tert-butyl N-[(2S)-4-methyl-1-oxopentan-2-yl]carbamate

Participants

Reaction Conditions

Reaction Steps

Boc-leucinol (3) (12.88 g, 58.9 mmol) was flushed with toluene and then purged with argon gas. It was dissolved in dimethylsulfoxide (dehydrated, 200 ml) and, after addition of triethylamine (22 ml, 158 mmol), cooled in a 15° C. water bath. Meanwhile, in another flask, sulfur trioxide-pyridine complex (25.3 g, 159 mmol) was dissolved in dehydrated DMSO (100 ml) and stirred for 10 minutes under argon stream. Cooling at 15° C., the sulfur trioxide solution was added dropwise (4 minutes) to the solution of Boc-leucinol (3), and, after further stirring of 8 minutes, the reaction mixture was poured into 1500 ml of cold water to terminate the reaction. Following extraction with ethyl acetate, the organic layer was washed with 0.1 M hydrochloric acid, water and saturated saline solution in the order, dried with anhydrous sodium sulfate, and concentrated after removal of the drying agent. Purification using a silica gel open column (250 g, ethyl acetate/hexane=1/5) gave the aimed compound, Boc-Leu-H (aldehyde) (4). Yield: 10.9 g (85.8%).

Provenance & Evidence