Tetrafluoroboric acid → Hedione

Participants

Reaction Steps

In a glove box under argon and at room temperature, 38 mg of [(COD)Ru(2-methylallyl)2 ] (0.12 mmole) and 36 mg (0.12 mmole) of (-)-Me-DuPHOS were dissolved in 5.38 g (24 mmole) of methyl-3-oxo-2-pentyl-1-cyclopentene-acetate in a glass beaker adapted for use in an autoclave which was equipped with a stirrer. Thereafter, 39 mg of HBF4 etherate (0.24 mmole; 32.7 μl, syringe) were gently added under stirring. After stirring for 4 h, 3.4 ml of this catalytic solution (containing about 0.075 mmole of catalyst) were transferred to another beaker, and another 8.38 g (37.4 mmole) of methyl 3-oxo-2-pentyl-1-cyclopentene-1-acetate (total amount about 53 mmole) were added to this. Working as previously described, the substrate was hydrogenated at a H2 pressure of 5×106Pa. The reaction was allowed to proceed for 20 h at room temperature. The autoclave was degassed, opened, and the catalyst was precipitated using pentane, filtered and the filtrate concentrated to obtain the desired Hedione®. The thus obtained product (yield 99% based on the above mentioned substrate) showed the following isomer ratios: cis/trans=97/3: (+)-cis/(-)-cis=80/20, 60% e.e.

Provenance & Evidence