Catalyzed stereoconvergent 1,4-additions to unsaturated carbonyls are rare but of high potential value. This letter details the development of enantioselective arylation reactions of boronic acids and β,γ-butenolides. These reactions are catalyzed by commercially available hydroxy­[(S)-BINAP]-rhodium­(I) dimer to afford stereochemically complex γ-butyrolactone derivatives. The reaction products provide functionality amenable to further manipulation and can lead to products with up to three contiguous stereocenters. The reaction proceeds under a dynamic kinetic resolution manifold by isomerizing the achiral starting material into an interconverting mixture of enantiomeric conjugate acceptors, followed by catalyst-controlled, enantiomer-selective 1,4-addition. Base-promoted racemization of the intermediate α,β-butenolide is possible due to the high kinetic and thermodynamic acidity of the γ-proton.

A quinidine-catalyzed diastereoselective addition of α-angelica lactone to β-halo-α-ketoesters is reported. The α-angelica lactone displays unusual regioselectivity in this reaction, acting as a nucleophile at the α-position to provide fully substituted glycolic esters with three contiguous stereocenters. Subsequent diastereoselective hydrogenation provides an additional stereocenter within the lactone.

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F our of the scanned 13 C NMR spectra were not phased correctly (3b, 3d, 3g, and 3j). The original FID files were reprocessed, and we have uploaded an updated Supporting Information file with the properly phased spectra.

The support of L.V.L. through an NSF REU grant was inadvertently omitted. The authors apologize for this oversight. The acknowledgment should read as follows. ■ ACKNOWLEDGMENTSFinancial support was provided by Award R35 GM118055 from the National Institute of General Medical Sciences. L.V.L. acknowledges support from the NSF REU program (CHE-1460874).