反应详情

A mixture of the benzhydryl ester from Example 28 (2.5 g, 4.79 mmol), tris-(triphenylphosphine(chlororhodium (3.5 g, 4.79 mmol) and dry toluene (75 ml) was refluxed under nitrogen for 5.5. hours. The reaction mixture was cooled. the rhodium complex was removed by filtration and the filtrate was poured slowly into petroleum ether (250 ml) with stirring. The precipitated solid, which was a mixture of rhodium complex and product, was collected. The product was purified by chromatography on a silica gel column (250 g) using 99:0.5 chloroform:ethyl acetate as eluent. Fractions of 4.5 ml were collected; fractions 1-47 discarded, 48-66 contained bis-(triphenylphosphine)carbonylchlororhodium, and 67-198 contained the product. NMR data indicated the product after chromatography to be the Δ3 isomer instead of the Δ2 isomer. A decoupling experiment showed the 2-methylene group at 3.3 ppm. to be coupled with the 3-proton at 6.6 ppm.

1. temperatureThe reaction mixture was cooled
2. customthe rhodium complex was removed by filtration
3. additionthe filtrate was poured slowly into petroleum ether (250 ml)
4. additiona mixture of rhodium complex and product
5. customwas collected
6. customThe product was purified by chromatography on a silica gel column (250 g)
7. customFractions of 4.5 ml were collected