Hydrochloric Acid → Triapenthenol

Participants

Reaction Steps

In a nitrogen atmosphere, a solution of 0.485 g (1.8 mmoles) of (S)-2-amino-1,1-diphenyl-4-methylpentan-1-ol in 5 ml of 1,2-dichloroethane was added dropwise at -78° C. to a solution comprising 1.8 ml (1.8 mmoles) of 1.00M borane-tetrahydrofuran solution and 2 ml of 1,2-dichloroethane, and the temperature of the mixture was raised from -78° C. to room temperature over about 2 hours. Thereafter, a solution of 0.31 g (1.2 mmoles, E/Z=99.9/0.1) of (E)-1-cyclohexyl-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-one in 3 ml of 1,2-dichloroethane was added dropwise to this solution, and stirring was carried out for 24 hours. The reaction product was decomposed with addition of 6 ml of 2N hydrochloric acid to the solution, and after removing (S)-2-amino-1,1-diphenyl-4-methylpentan-1-ol hydrochloride by filtration, the organic layer was washed with water and concentrated under reduced pressure The residue was purified on a column packed with 2 g of silica gel with chloroform as a developing solvent to obtain (-)-(E)-1-cyclohexyl-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol. The conversion was 100%, and the composition of the product was: E-form alcohol, 99.1% and Z-form alcohol, 0.9%. The enantiomer ratio of the E-form alcohol was: (+)-isomer, 16.3% and (-)-isomer, 83.7%.

Provenance & Evidence