Asymmetric synthesis of sulfinyl-substituted arene chromium tricarbonyl complexes

The synthesis of (SRSS)- [(phenylsulfinyl)benzene] chromium tricarbonyl 5 and (SRSS)-[(p-tolylsulfinyl)benzene] chromium tricarbonyl 6 is achieved via a nucleophilic displacement reaction between the anion derived from (benzene) chromium tricarbonyl 9 and a suitable sulfinate ester. Replacing the sulfinate ester with a chiral sulfinyl-transfer reagent allows the isolation of the non-racemic sulfinyl-substituted complexes with good enantioselectivities (ee 80-89%) under optimised conditions. The use of Kagan's cyclic sulfite methodology for the synthesis of an enantiomerically pure tert-butylsulfinyl complex is unsuccessful, but results in the identification of a novel fragmentation-isomerisation process of the intermediate sulfinate.