Preparation of new layered double hydroxides exchanged with osmate for asymmetric dihydroxylation of olefins to vicinal diols

A process for the preparation of the catalyst LDH-osmate of the formula [MII(1−x)MIIIx(OH)2][OsO42−]x/2.zH2O wherein the said process comprises reacting potassium osmate of formula K2OsO42H2O with a LDH of formula [MII(1−x)MIIIx(OH)2][An−]x/n.zH2O wherein MII is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+ and MIII is a trivalent ion selected from the group consisting of Al3+, Cr3+, Mn3+, Fe3+ and Co3+ and An− is an interstitial anion selected from nitrate, carbonate and chloride, x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4, in an aqueous solvent at a temperature ranging between 20 to 30° C. for a period of 5 to 24 h under the nitrogen atmosphere followed by washing to obtain the desired catalyst.

A method for the preparation of vicinal diols using the recyclable catalysts LDH-osmates of the formula [MII(1−x)MIIIx(OH)2][OsO42−]x/2.zH2O wherein MII is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+;

• MIII is a trivalent ion selected from the group consisting of Al3+, Cr3+, Mn3+, Fe3+ and Co3+ and z is the number of water molecules in catalytic amounts by dihydroxylation of olefins employing an oxidant in a solvent selected from water, acetone, acetonitrile, t-butanol and a mixture thereof at a temperature in the range of −20 to +100° C. for a period of 0.5 to 24 h, and obtaining the pure product vicinal diol.

A process for the preparation of chiral vicinal diols using the recyclable catalyst LDH-osmates of the formula [MII(1−x)MIIIx(OH)2][OsO42−]x/2.zH2O, wherein MII is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+;

• MIII is a trivalent ion selected from the group consisting of Al3+, Cr3+, Mn3+, Fe3+ and Co3+;
• and x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4, in catalytic amounts by asymmetric dihydroxylation of olefins employing an oxidant in the presence of a cinchona alkaloid compound and a chiral ligand in a solvent selected from water, acetone, acetonitrile, t-butanol and a mixture thereof at a temperature in the range of −20 to +100° C. for a period of 0.5 to 24 h, and obtaining the pure product of chiral vicinal diol.