A new chiral sulfonamide ligand based on tartaric acid: synthesis and application in the enantioselective addition of diethylzinc to aldehydes and ketones

A new sulfonamide ligand based on l-tartaric acid was synthesized and was employed as a chiral ligand in the enantioselective addition of diethylzinc to aldehydes, giving rise to the best enantiomeric excess up to 83% with 5 mol % of catalyst loading. Moreover, the addition of diethylzinc to ketones can also be achieved with good to excellent enantioselectivities by employing 7 mol % of the catalyst under mild conditions.

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C-(1S,2R,4S-2-Hydroxy-7,7-dimethyl-bicyclo[2.2.1]hept-1-yl)-N-{4S,5S-5-[(1S,2R,4S-2-hydroxy-7,7-dimethyl-bicyclo[2.2.1]hept-1-ylmethanesulfonylamino)-methyl]-2,2-dimethyl-[1,3]dioxolan-4-ylmethyl}-methanesulfonamideC27H48N2O8S2Ee = 100%[α]D25=-42.6 (c 0.5, CHCl3)