Rhodium-Catalyzed Enantioselective Synthesis of 1,2-Diols

Key words

rhodium - diols - phebox ligand

Significance

Chiral diols are useful synthetic motifs in organic synthesis. Common methods for their synthesis include dihydroxylation, hydrogenation of hydroxyketones, and hydrolysis of epoxides. The authors report an enantioselective 1,2-diboration of alkenes leading to optically active diols after oxidation.

Comment

Morken showed a similar diboration of terminal alkenes with a platinum catalyst with enantioselectivities up to 94% (J. Am. Chem. Soc. 2009, 131, 13210). The authors present a rhodium-catalyzed diboration–oxidation of terminal alkenes providing enantioselectivities up to 99%. However, disubstituted alkenes proved to be more difficult. 1-Methylstyrene gave the diol with a moderate 76% ee, whereas β-methylstyrene, 1,2-dihydronaphthalene, and trans-stilbene did not react.