Practical Synthesis of Optically Active Alcohols via Asymmetric Transfer Hydrogenation of Aromatic Ketones Using Chiral Rh(III)–Monosulfonamide Ligand Complex in Aqueous Media

Abstract

A series of monosulfonamide derivatives were synthesized and tested as chiral ligands in the Ru(II),Rh(III)-catalyzed transfer hydrogenation of aromatic ketones in aqueous sodium formate and isopropanol/potassium hydroxide. Possible secondary Cp*methyl-π sulfonamide benzene ring interaction is envisaged and supported by calculations.

Keywords:

• Asymmetric transfer hydrogenation
• monosulfonamide ligands
• Rh-Cp^*
• Ru–arene complexes

ACKNOWLEDGMENTS

We gratefully acknowledge support for this project by the Consejo Nacional de Ciencia y Tecnología (CONACyT) Grants 37827-E (R. S.) and 55802 (C. A. de P.), and Dirección General de Educación Superior Tecnológica (DGEST Grant 310.06-P), A. L. C. thanks the National Science Foundation for partial support, Grant CHE-0719575. A graduate scholarship from CONACyT provided support for N. A. Cortez.

Notes

Note. Absolute configurations are all (R) except with 3b (S), assigned by comparing the specific rotations with the literature values.^[7a]

^a 25 °C, using a mixture of iPrOH/KOH, S/C 33.

^b 40 °C, using a mixture of water/sodium formate in air, S/C 200.

^c Measured by GC analysis of the acetylated alcohol with a chiral capillary column β–DEX 120.

Note. ^a 25 °C, using a mixture of iPrOH/KOH, S/C 33.

^b 40 °C, using a mixture of water/sodium formate in air S/C 200.

^c Measured by GC analysis of the acetylated alcohol with a chiral capillary column β–DEX 120.

^d The alcohol configuration was R.