Palladium-catalyzed asymmetric allylic alkylation (AAA) with alkyl sulfones as nucleophiles |
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Authors: | Barry M Trost Zhiwei Jiao Hadi Gholami |
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Institution: | School of Chemistry, Sun Yat-Sen University, Guangzhou 510275 China.; Departmentof Chemistry, Stanford University, Stanford CA 94305-5080 USA, |
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Abstract: | An efficient palladium-catalyzed AAA reaction with a simple α-sulfonyl carbon anion as nucleophiles is presented for the first time. Allyl fluorides are used as superior precursors for the generation of π-allyl complexes that upon ionization liberate fluoride anions for activation of silylated nucleophiles. With the unique bidentate diamidophosphite ligand ligated palladium as catalyst, the in situ generated α-sulfonyl carbon anion was quickly captured by the allylic intermediates, affording a series of chiral homo-allylic sulfones with high efficiency and selectivity. This work provides a mild in situ desilylation strategy to reveal nucleophilic carbon centers that could be used to overcome the pKa limitation of “hard” nucleophiles in enantioselective transformations.A variety of “hard” α-sulfonyl carbanions of aryl, heteroaryl and alkyl sulfones were successfully employed as nucleophiles in palladium-catalyzed asymmetric allylic alkylation with excellent enantioselectivities. |
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