Asymmetric Addition of Diethylzinc to Ketones promoted by Tartaric Acid Derivatives

Abstract

The preparation of new sulfonamide ligands derived from L-tartaric acid and camphor sulfonyl chloride are described. The employment in the titanium tetraisopropoxide-promoted enantioselective addition of diethylzinc to ketones has been studied. The best enantiomeric excess is up to 99% with 7 mol% catalyst loading at room temperature.

Keywords:

• Asymmetric addition
• Diethylzinc
• Ketone
• Sulfonamide
• Tartaric acid

ACKNOWLEDGMENTS

We are grateful to the National Nature Science Foundation of China (Nos. 20472078 and 30572234) for its support of this study.

Notes

^a Isolated yields.

^b The enantiomeric excess was determined by chiral HPLC using OJ-H column.

^a Isolated yields.

^b The enantiomeric excess was determined by chiral HPLC using OD-H or OJ-H column and the configuration was determined by comparision of specific rotations with literature data.

^c No desired product was detected.