This paper reports the desymmetrization of cyclohexadienones through stereoselective intramolecular aza-Michael addition with a tethered chiral sulfinamide nucleophile. The reaction was facilitated by phase-transfer catalysis and produced various nitrogen-containing bicyclic compounds with a yield of up to 93% and a diastereomeric ratio of up to >20:1.
View Article and Find Full Text PDFThis paper reports the kinetic resolution of racemic secondary alcohols (-nucleophiles) via stereoselective intramolecular allylic substitution. The reaction was enabled by synergistic palladium and chiral phosphoric acid catalysis and produced chiral -1,3-disubstituted 1,3-dihydroisobenzofurans with a selective factor of up to 60.9 and a diastereomeric ratio of up to 7.
View Article and Find Full Text PDFThe asymmetric induction afforded by a chiral sulfinyl group in a palladium/Brønsted-acid-catalyzed intramolecular allylic amination was investigated. Predictions of the diastereoselectivity for various substrates under assumed total thermodynamic control were obtained from density functional theory (DFT), and the correlation with experimental data demonstrates abrupt changes to kinetic control across the substrate scope. The resulting heterocyclic product was readily converted to valuable isoindoline-1-carboxylic acid esters by a two-step oxidation sequence, providing asymmetric access to a key unnatural α-amino acid scaffold.
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