抄録
Robinson annelation under supercritical CO2 in the presence of metal oxide was studied to synthesize fused polycyclic compounds such as the series of steroid compounds from the low substrates. Experiments were conducted in the presence of MgO catalyst at 35 to 180°C at various pressures in a batch wise operation. The reaction at various pressures at a constant temperature of 100°C produced 8a-methyl-3,4,8,8a-tetrahydro-2H,7H-naphthalene-1,6-dione 1 as one of minor products, whereas 2-methyl-2-(3-oxo-butyl)-cyclohexane-1,3-dione 2 as a main product, which is the product by Michael reaction between cyclohexane and 3-butene-2-one. The reaction at a higher temperature of 180°C was further investigated at several pressures, leading to the better yield of 1 than that at 100°C and the maximum yield of 57% at 20 MPa. However, under the constant pressure and temperature, the reaction would have a limitation in the yield of 1 up to 57%, we found that the pressure manipulation and temperature manipulation in one pot can be achieved successfully in high yield (95%) and high selectivity (95%) of 1. In this presentation we would like to show the other results in the presence of various heterogeneous metal oxide catalysts, and further successful improvement of this reaction.
The one-step Robinson annelation from 2-methyl-cyclohexane-1,3-dione with 3-buten-2-one can be achieved in high yield (95%) and high selectivity (95%) by pressure and temperature manipulation using supercritical carbon dioxide in the presence of MgO catalyst, whose method could be applied for various ketones to synthesize fused polycyclic compounds.
